Tesis: "Inoculum"

1

Thaning, Christian. "Ways of managing Sclerotinia sclerotiorum inoculum /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv), 2000. http://epsilon.slu.se/avh/2000/91-576-5790-4.pdf.

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2

Baijnath, Sharika. "Effect of inoculum source, inoculum pressure and cultivar on development of black scurf on potatoes in South Africa". Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/24650.

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Rhizoctonia solani inoculum can be present either as soil- or tuber-borne sclerotia or hyphae. Although both inoculum sources play a role in disease development, it is not clear which of the two is more important. Successive cultivation of potato crops increases R. solani soil inoculum load resulting in an escalation in disease incidence and severity. The use of tolerant cultivars, however, can effectively reduce inoculum levels thereby decreasing disease intensity. Four pot trials were conducted; the objective of the first two pot trials was to determine the effect of tuber and soil-borne inoculum and stolon inoculations on disease development in sandy and clay loam soils. The second two pot trials were aimed at determining susceptibility levels of five cultivars. Two field trials were planted over two growing seasons in the same soils, using three inoculum levels. Results from the pot trials showed that tubers harvested from inoculated sandy soils developed significantly more disease than those harvested from clay loam soils. Of the three inoculum sources, stolon inoculation and seed-borne inoculum resulted in significantly more disease on progeny tubers than those from R. solani spiked soils. Although none of the cultivars proved to be tolerant to R. solani, BP1 was less susceptible to R. solani at temperatures between 21-26oC. More severe disease symptoms were observed under cooler temperatures on all cultivars. Results from the field trial showed the cultivation of potatoes in the same soil over two growing seasons resulted in an increase in diseased (black scurf) tubers. Furthermore, black scurf was most severe on tubers from soils infested with the highest concentration of inoculum. There were significant disease severity differences, with initial soil inoculum levels being directly proportional to final disease severity. Future studies in South Africa should focus on investigating the genetic composition of various cultivars; the effect of soil type and pH on the pathogenicity of R. solani and the use of molecular diagnostic tools to detect and quantify R. solani in soils.
Dissertation (MSc)--University of Pretoria, 2012.
Microbiology and Plant Pathology
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3

Spies, Christoffel F. J. (Christoffel Frederik Jakobus). "The inoculum ecology of Botrytis cinerea in Rooibos nurseries". Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/20943.

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Thesis (MScAgric)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: Grey mould, caused by Botrytis cinerea, is the most important foliar disease of rooibos seedlings. Although the disease is primarily controlled with applications of fungicides, the improvement of cultural methods of disease management should lessen this dependence on chemical control. Such improvements would, however, not be possible without knowledge of the inoculum sources and dispersal of the pathogen. The aim of this study was to investigate the inoculum ecology of B. cinerea in rooibos nurseries in order to identify primary sources of inoculum and to improve the environmentally friendly management of the disease. The study was conducted in four nurseries over two production seasons (March to July 2003 and 2004). Levels of airborne inoculum of B. cinerea were monitored on a monthly basis inside and around the nurseries with spore traps. Samples of plant material and organic debris were taken in the corresponding areas to determine the incidence of plant material infected by the pathogen and the incidences of grey mould in the nurseries were recorded. Low numbers of B. cinerea colonies were observed on the spore traps. Similar levels of airborne inoculum were observed inside and around the nurseries. The incidence of plant material yielding B. cinerea was higher outside the nurseries than inside, indicating the importance of such materials as potential sources of inoculum. Since patterns of airborne inoculum observed in this study confirmed reports of the local dispersal of B. cinerea, the removal of possible hosts outside the nurseries could aid in the management of grey mould in rooibos nurseries. Resistance to dicarboximide fungicides is a genetically stable trait in B. cinerea, and therefore has the potential to be used as a phenotypic marker. This marker can be used to gain knowledge on the dispersal of B. cinerea inoculum inside and outside rooibos nurseries. Isolates of B. cinerea collected from the air and from plant material in and around four rooibos nurseries were assessed for resistance to iprodione at 1 and 3 μg/ml a.i. Some of the isolates showed resistance to iprodione at 1 μg/ml a.i. However, none of the isolates showed resistance at 3 μg/ml a.i. iprodione. The initial incidence of dicarboximide-resistance at the nurseries was slightly higher than expected. As the season progressed, the incidence of iprodione-resistant isolates decreased towards May, after which an increase was observed towards July. A relatively high percentage of isolates collected outside the nurseries was found to be dicarboximide-resistant. Two of the nurseries had a significant higher incidence of resistant isolates on plant material collected inside, than on plant material collected outside the nursery. However, when looking at resistance levels of airborne isolates, no significant differences were found in the incidence of resistant isolates sampled inside and outside the four nurseries. The data indicated the importance of organic debris and seed-borne infections in the survival and dispersal of dicarboximide-resistant isolates of the pathogen. With the current emphasis on organic agriculture the knowledge gained in this study presents valuable possibilities of improving the cultural management of grey mould in rooibos nurseries.
AFRIKAANSE OPSOMMING: Vaalvrot, veroorsaak deur Botrytis cinerea, is die belangrikste bo-grondse siekte van rooibossaailinge. Alhoewel die beheer van die siekte hoofsaaklik op die gebruik van fungisiede berus, behoort die verbetering van verbouingspraktyke hierdie afhanklikheid van chemiese beheer te verminder. Sulke verbeteringe sal egter slegs moontlik wees indien voldoende kennis van die inokulumbronne en verspreiding van die patogeen beskikbaar is. Die doel van hierdie ondersoek was om die inokulum ekologie van B. cinerea in rooibos kwekerye te ondersoek sodat primêre inokulumbronne opgespoor en omgewingsvriendelike siektebestuurspraktyke verbeter kan word. Die ondersoek is in vier kwekerye oor twee produksie seisoene (Maart tot Julie 2003 en 2004) uitgevoer. Vlakke van luggedraagde inokulum van B. cinerea is op ’n maandelikse basis met behulp van spoorvangers binne en buite die kwekerye gemonitor. Monsters van plantmateriaal en organiese materiaal is in ooreenstemmende areas geneem om die voorkoms van B. cinerea geïnfekteerde plantmateriaal vas te stel en die voorkoms van vaalvrot in die kwekerye is aangeteken. Min B. cinerea kolonies is op die spoorvangers waargeneem. Soortgelyke vlakke van luggedraagde inokulum is binne en buite die kwekerye waargeneem. Die hoër voorkoms van B. cinerea geïnfekteerde plantmateriaal buite die kwekerye as binne, dui op die belang van sulke materiaal as potensiële inokulumbronne. Aangesien die patrone van luggedraagde inokulum, soos waargeneem in hierdie ondersoek, ander berigte van B. cinerea se beperkte verspreidingsvermoë bevestig, kan die verwydering van moontlike alternatiewe gashere buite die kwekerye die bestuur van die siekte binne die kwekerye verbeter. Weerstand teen dikarboksimied fungisiede is ’n geneties-stabiele kenmerk in B. cinerea en het daarom potensiaal om as ’n fenotipiese merker gebruik te word. Hierdie merker kan gebruik word om kennis aangaande die verspreiding van B. cinerea in en om rooibos kwekerye in te samel. Botrytis cinerea isolate in lug en op plantmateriaal in en om vier rooibos kwekerye is gedurende 2003 en 2004 versamel. Die isolate is vir weerstandbiedendheid teen iprodioon by konsentrasies van 1 en 3 μg/ml aktiewe bestandeel (a.b.) getoets. Isolate met weerstand teen 1 μg/ml a.b. iprodioon is waargeneem, maar nie teen 3 μg/ml nie. Die aanvanklike voorkoms van dikarboksimiedweerstand by die kwekerye was hoër as verwag. Hierdie vlak het egter gedaal met die verloop van die seisoen tot in Mei, waarna ’n toename tot in Julie waargeneem is. Die persentasie dikarboksimied-weerstandbiedende isolate buite die kwekerye was relatief hoog. In twee van die kwekerye was die voorkoms van weerstandbiedende isolate op plantmateriaal in die kwekerye betekenisvol hoër as op plantmateriaal buite die kwekerye. Daar was egter geen betekenisvolle verskille in die voorkoms van luggedraagde weerstandbiedende isolate nie, ongeag van die kwekery of posisie. Die data dui op die belang van organiese materiaal en saadgedraagde infeksies in die oorlewing en verspreiding van dikarboksimied-weerstandbiedende isolate van die patogeen. Met die huidige klem op organiese landbou bied die inligting wat in hierdie ondersoek versamel is moontlike praktyke wat geïmplementeer kan word om die beheer van vaalvrot in kwekerye met behulp van verbouingspraktyke te verbeter.

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4

Williamson, Taryn Lori. "Evaluating Fungal Pathogen Inoculum Loads in Field Seed Banks". BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8277.

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Quantification of soilborne pathogen inoculum loads is important in both agricultural and wildland settings. Quantitative Polymerase Chain Reaction (qPCR) methods using SYBR Green chemistry have been shown to be useful for quantifying fungal inoculum loads in environmental samples. The purpose of this study was to develop a method to quantify fungal pathogen inoculum loads in soil seed banks using a qPCR method with SYBR Green chemistry. The invasive annual grass Bromus tectorum was chosen for this seed bank study. There were three objectives: 1) to design target-specific primers for three fungal pathogens known to be important in Bromus tectorum seed banks, 2) to develop a procedure for measuring inoculum loads in field samples, including optimization of qPCR standard curves and protocols, for these pathogens, and 3) to perform qPCR using this methodology on a representative set of field samples to quantify pathogen DNA in seed bank soil and surface litter. The three pathogens were chosen for quantification based on their hypothesized roles in Bromus tectorum stand failure: the seed pathogen Pyrenophora semeniperda, an undescribed species of Fusarium seed rot pathogen belonging to the F. tricinctum species group (FTSG), and the newly-described causal agent of bleach blonde syndrome (Clarireedia capillus-albis). Primers designed for each pathogen were shown to be target-specific in tests against each other and 12 other fungal species cultured from B. tectorum seed banks. Subsequently developed standard curves for each pathogen had R2 values > 0.98, efficiencies between 90 and 110 percent, and generally optimal dissociation curves. Inoculum loads were expressed for each pathogen as picograms of DNA per microliter of extracted soil or surface litter. Significant differences in measured inoculum loads were found between the targeted pathogens and between soil and litter samples for each pathogen. The data provided reinforces that the SYBR Green qPCR method provides a potentially useful tool for the study of field seed and seedling diseases across a wide spectrum of both wildland and agronomic applications.

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5

Baroon, Z., A. Yateem y T. Al-Surrayai. "Enhancement of Nitraria retusa Growth by Rhizospheric Microbial Inoculum". University of Arizona (Tucson, AZ), 2009. http://hdl.handle.net/10150/556557.

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Native desert vegetation in Kuwait has been severely depleted due to both natural and anthropogenic factors and are facing the danger of extinction. Symbiotic rhizospheric microflora influences the growth of plant communities in different ecosystems. The objective of this study is to emphasize the enhancing effect of rhizospheric microbial inoculum on the growth of native desert plants. A shed house experiment was conducted using Nitraria retusa which was selected on the basis of its importance and potential for the revegetation of desert flora. The plant was propagated in three different soil treatments: soil with added rhizospheric inoculum (SI), soil with added amendment (SP) and soil with added rhizospheric inoculum and amendment (SIP). The growth performance of N. retusa in terms of shoot height and number of leaves was monitored on a monthly basis during 120 d experimental duration and compared with control soil treatment (SC) which was soil without any additions. The results clearly demonstrated the enhancing effect of rhizospheric microbial inoculum when combined with fertilizers in soil amended treatment (SIP) on the growth of N. retusa. Additionally, N. retusa in the inoculated treatment (SI) maintained a high survival rate during the experiment compared to other treatments.

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6

com, Yinglongchen@hotmail y Yinglong Chen. "Optimization of Scleroderma spore inoculum for Eucalyptus nurseries in China". Murdoch University, 2006. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060809.93928.

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Scleroderma, a genus of ectomycorrhizal (ECM) fungi, is often associated with trees in disturbed habitats and is therefore considered to be suitable for use in plantation forestry. This study investigated aspects of Scleroderma and its mycorrhizas with the view to its future use in plantation forestry in south China. Spores were chosen as inoculum as they are preferred by nursery managers in south China, due to the lack of on-site fermentation and storage facilities. To determine the need for inoculation, Eucalyptus plantations in south China were sampled for sporocarps and mycorrhizas over two years. This study revealed a low diversity of ECM fungi consisting of 15 taxa fruiting beneath Eucalyptus plantations. The most common genera were Scleroderma and Pisolithus, but they were infrequent and the extent of root colonization was poor. Bioassay trials with E. urophylla as a bait host, using soils collected from 8 eucalypt plantations, confirmed low levels of inoculum in field soil. It was concluded that introduction of suitable ECM symbionts into eucalypt nurseries in south China is desirable in the future. As the Scleroderma genus has not been well studied in Australasia or SE Asia, over 140 collections gathered mainly from eucalypt plantations in south China and south-western Australia were described using sporocarp and spore morphology. Twelve Scleroderma taxa were recognized from collections made from under eucalypt plantations in south-western Australia and 6 of these were collected from under eucalypt plantations in south China. In conjunction with classical taxonomy, 30 collections, including those used in inoculation trials, were further characterized by phylogenetic analyses of ITS or LSU rDNA sequences. These studies supported classical delineation of some Scleroderma species but not all. Although a limited number of collections were amplified, phylogenetic results showed that most collections in this study were distinct from the European and Malaysian taxa extracted from GenBank (89% bootstrap support for both LSU and ITS regions). In order to optimise spore germination and root colonization, two glasshouse trials were established to examine suitable spore density and spore storage conditions on E. globulus and E. urophylla. A spore density of 105 spores seedling-1 was identified as a suitable dose for promoting root colonization. Spores stored for 5 years at low temperate (4 0C) were almost as effective as freshly collected spores in forming mycorrhizas. As the compatibility of Scleroderma fungi with plantation trees is unknown, a glasshouse experiment examined the ability of 15 collections of Scleroderma to form mycorrhizas with seedlings of six plantation trees (Acacia mangium, A. mearnsii, E. globulus, E. urophylla, Pinus elliottii and P. radiata) in a nursery potting mix. Most collections were able to aggressively colonize eucalypts and pines, while roots of acacias were poorly colonized. As the Australian collections were more effective in colonizing short roots on eucalypts than the Chinese collections, it was concluded Scleroderma should be sourced from outside China for inoculating eucalypts in Chinese nurseries. To optimize nursery practices to meet the demand for high quality seedlings and clonal lines of E. urophylla and hybrids, for outplanting in south China, effects of rooting medium and inoculation with 6 Scleroderma collections on the growth of E. urophylla were examined in a nursery in south China. Four types of soil taken from eucalypt plantations in south China were compared to a potting mix composed of vermiculite, peat and sand. The inoculant Scleroderma fungi were able to out-compete indigenous mycorrhizal fungi in the rooting media. However, the potting mix was superior to soils both for plant growth and ECM development under nursery conditions. This research should facilitate the use of Scleroderma spores in eucalypt nurseries in south China. Spore orchards could be set up in China using Australian Scleroderma spp. from under eucalypts. Spores could be stored dry at 4 0C until they are required for inoculation in potting mixes in containerized nurseries. However, before commercial application, further work on persistence of Scleroderma in the nursery and field, and responses of trees in the field to inoculation, needs to be undertaken.

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7

Lamprecht, Corne. "UASB granulation enhancement by microbial inoculum selection and process induction". Thesis, Stellenbosch: University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1477.

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Thesis (PhD (Food Science))--University of Stellenbosch, 2009.
In the absence of anaerobic granules, anaerobically digested sewage sludge is frequently used to seed industrial upflow anaerobic sludge blanket (UASB) reactors. Because of its flocculent nature, start-up with digested sludge instead of granular sludge proceeds much slower and presents various operational problems. Any manner in which the granulation of digested sludge can be enhanced would benefit UASB reactor start-up and application in developing countries such as South Africa. The main objective of this dissertation was to improve granulation and reduce UASB reactor start-up by using pre-treated digested sludge as seed. The sludge was pre-treated based on the batch granulation-enhancement model of Britz et al. (2002). The main aim of the model was to improve extracellular polymer (ECP) production of lactate-utilising populations by applying short-term controlled organic overloading in a mechanically agitated environment. The batch granulation-enhancement (pre-treatment) process was applied to an ECP-producing digester strain, Propionibacterium jensenii S1. Non-methanogenic aggregates were formed when batch units were incubated on a roller-table instead of a linear-shake platform. Larger, more stable aggregates were obtained in the presence of apricot effluent medium. Preliminary batch granulation-enhancement studies confirmed that using the roller-table as mixing system had a positive influence on batch granulation-enhancement. The roller-table showed the most potential for handling larger volumes in comparison to a linear-shake waterbath and linear-shake platform. The addition of 450 mg.L-1 Fe2+ at the start of the study also influenced aggregate numbers positively. These studies revealed that pre-treatment results varied depending on the seed sludge source. A denaturing gradient gel electrophoresis (DGGE) method was applied for the detection of Archaea in digested sludges and UASB granules. In addition, a methanogenic marker containing methanogens important to the granulation process was constructed to aid identification. The positive influence of DMSO and “touchdown” PCR on the elimination of artifactual double bands in DGGE fingerprints were also demonstrated. Results revealed that only one of the four digested sludges tested contained Methanosaeta concilii (critical to granular nuclei formation) while it was present in all the UASB granules regardless of substrate type. Four digested sludges were obtained from stable secondary digesters. DGGE indicated the presence of M. concilii in all sludges. The Athlone 4Sb-sludge was the only sludge which exhibited measurable methanogenic activity during substrate dependent activity testing. The ST-sludge showed the highest increase in volatile suspended solids (VSS) particles ≥0.25 mm2. Laboratory-scale UASB reactor start-up was done with both sludges and start-up proceeded better in the Athlone 4Sb-reactor. Athlone 4Sb-sludge batches were pre-treated in a rolling-batch reactor in the presence of either lactate or sucrose and used to seed lab-scale UASB reactors B (sucrose seed) and C (lactate seed). Start-up efficiencies were compared to a control (Reactor A). Overall Reactor B was more efficient that the control. At the end of the study the Reactor B sludge had a higher methanogenic activity than the control reactor. It also had the highest increase in VSS ≥1.0 mm2. Pre-treatment of digested sludge in the presence of sucrose, therefore, aided granulation and reduced UASB reactor start-up time.

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8

Chen, Yinglong. "Optimization of Scleroderma spore inoculum for Eucalyptus nurseries in China". Thesis, Chen, Yinglong (2006) Optimization of Scleroderma spore inoculum for Eucalyptus nurseries in China. PhD thesis, Murdoch University, 2006. https://researchrepository.murdoch.edu.au/id/eprint/665/.

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Scleroderma, a genus of ectomycorrhizal (ECM) fungi, is often associated with trees in disturbed habitats and is therefore considered to be suitable for use in plantation forestry. This study investigated aspects of Scleroderma and its mycorrhizas with the view to its future use in plantation forestry in south China. Spores were chosen as inoculum as they are preferred by nursery managers in south China, due to the lack of on-site fermentation and storage facilities. To determine the need for inoculation, Eucalyptus plantations in south China were sampled for sporocarps and mycorrhizas over two years. This study revealed a low diversity of ECM fungi consisting of 15 taxa fruiting beneath Eucalyptus plantations. The most common genera were Scleroderma and Pisolithus, but they were infrequent and the extent of root colonization was poor. Bioassay trials with E. urophylla as a bait host, using soils collected from 8 eucalypt plantations, confirmed low levels of inoculum in field soil. It was concluded that introduction of suitable ECM symbionts into eucalypt nurseries in south China is desirable in the future. As the Scleroderma genus has not been well studied in Australasia or SE Asia, over 140 collections gathered mainly from eucalypt plantations in south China and south-western Australia were described using sporocarp and spore morphology. Twelve Scleroderma taxa were recognized from collections made from under eucalypt plantations in south-western Australia and 6 of these were collected from under eucalypt plantations in south China. In conjunction with classical taxonomy, 30 collections, including those used in inoculation trials, were further characterized by phylogenetic analyses of ITS or LSU rDNA sequences. These studies supported classical delineation of some Scleroderma species but not all. Although a limited number of collections were amplified, phylogenetic results showed that most collections in this study were distinct from the European and Malaysian taxa extracted from GenBank (89% bootstrap support for both LSU and ITS regions). In order to optimise spore germination and root colonization, two glasshouse trials were established to examine suitable spore density and spore storage conditions on E. globulus and E. urophylla. A spore density of 105 spores seedling-1 was identified as a suitable dose for promoting root colonization. Spores stored for 5 years at low temperate (4 0C) were almost as effective as freshly collected spores in forming mycorrhizas. As the compatibility of Scleroderma fungi with plantation trees is unknown, a glasshouse experiment examined the ability of 15 collections of Scleroderma to form mycorrhizas with seedlings of six plantation trees (Acacia mangium, A. mearnsii, E. globulus, E. urophylla, Pinus elliottii and P. radiata) in a nursery potting mix. Most collections were able to aggressively colonize eucalypts and pines, while roots of acacias were poorly colonized. As the Australian collections were more effective in colonizing short roots on eucalypts than the Chinese collections, it was concluded Scleroderma should be sourced from outside China for inoculating eucalypts in Chinese nurseries. To optimize nursery practices to meet the demand for high quality seedlings and clonal lines of E. urophylla and hybrids, for outplanting in south China, effects of rooting medium and inoculation with 6 Scleroderma collections on the growth of E. urophylla were examined in a nursery in south China. Four types of soil taken from eucalypt plantations in south China were compared to a potting mix composed of vermiculite, peat and sand. The inoculant Scleroderma fungi were able to out-compete indigenous mycorrhizal fungi in the rooting media. However, the potting mix was superior to soils both for plant growth and ECM development under nursery conditions. This research should facilitate the use of Scleroderma spores in eucalypt nurseries in south China. Spore orchards could be set up in China using Australian Scleroderma spp. from under eucalypts. Spores could be stored dry at 4 0C until they are required for inoculation in potting mixes in containerized nurseries. However, before commercial application, further work on persistence of Scleroderma in the nursery and field, and responses of trees in the field to inoculation, needs to be undertaken.

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9

Chen, Yinglong. "Optimization of Scleroderma spore inoculum for Eucalyptus nurseries in China". Chen, Yinglong (2006) Optimization of Scleroderma spore inoculum for Eucalyptus nurseries in China. PhD thesis, Murdoch University, 2006. http://researchrepository.murdoch.edu.au/665/.

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Scleroderma, a genus of ectomycorrhizal (ECM) fungi, is often associated with trees in disturbed habitats and is therefore considered to be suitable for use in plantation forestry. This study investigated aspects of Scleroderma and its mycorrhizas with the view to its future use in plantation forestry in south China. Spores were chosen as inoculum as they are preferred by nursery managers in south China, due to the lack of on-site fermentation and storage facilities. To determine the need for inoculation, Eucalyptus plantations in south China were sampled for sporocarps and mycorrhizas over two years. This study revealed a low diversity of ECM fungi consisting of 15 taxa fruiting beneath Eucalyptus plantations. The most common genera were Scleroderma and Pisolithus, but they were infrequent and the extent of root colonization was poor. Bioassay trials with E. urophylla as a bait host, using soils collected from 8 eucalypt plantations, confirmed low levels of inoculum in field soil. It was concluded that introduction of suitable ECM symbionts into eucalypt nurseries in south China is desirable in the future. As the Scleroderma genus has not been well studied in Australasia or SE Asia, over 140 collections gathered mainly from eucalypt plantations in south China and south-western Australia were described using sporocarp and spore morphology. Twelve Scleroderma taxa were recognized from collections made from under eucalypt plantations in south-western Australia and 6 of these were collected from under eucalypt plantations in south China. In conjunction with classical taxonomy, 30 collections, including those used in inoculation trials, were further characterized by phylogenetic analyses of ITS or LSU rDNA sequences. These studies supported classical delineation of some Scleroderma species but not all. Although a limited number of collections were amplified, phylogenetic results showed that most collections in this study were distinct from the European and Malaysian taxa extracted from GenBank (89% bootstrap support for both LSU and ITS regions). In order to optimise spore germination and root colonization, two glasshouse trials were established to examine suitable spore density and spore storage conditions on E. globulus and E. urophylla. A spore density of 105 spores seedling-1 was identified as a suitable dose for promoting root colonization. Spores stored for 5 years at low temperate (4 0C) were almost as effective as freshly collected spores in forming mycorrhizas. As the compatibility of Scleroderma fungi with plantation trees is unknown, a glasshouse experiment examined the ability of 15 collections of Scleroderma to form mycorrhizas with seedlings of six plantation trees (Acacia mangium, A. mearnsii, E. globulus, E. urophylla, Pinus elliottii and P. radiata) in a nursery potting mix. Most collections were able to aggressively colonize eucalypts and pines, while roots of acacias were poorly colonized. As the Australian collections were more effective in colonizing short roots on eucalypts than the Chinese collections, it was concluded Scleroderma should be sourced from outside China for inoculating eucalypts in Chinese nurseries. To optimize nursery practices to meet the demand for high quality seedlings and clonal lines of E. urophylla and hybrids, for outplanting in south China, effects of rooting medium and inoculation with 6 Scleroderma collections on the growth of E. urophylla were examined in a nursery in south China. Four types of soil taken from eucalypt plantations in south China were compared to a potting mix composed of vermiculite, peat and sand. The inoculant Scleroderma fungi were able to out-compete indigenous mycorrhizal fungi in the rooting media. However, the potting mix was superior to soils both for plant growth and ECM development under nursery conditions. This research should facilitate the use of Scleroderma spores in eucalypt nurseries in south China. Spore orchards could be set up in China using Australian Scleroderma spp. from under eucalypts. Spores could be stored dry at 4 0C until they are required for inoculation in potting mixes in containerized nurseries. However, before commercial application, further work on persistence of Scleroderma in the nursery and field, and responses of trees in the field to inoculation, needs to be undertaken.

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10

Balko, Tamara. "Characterization of the inoculum effect with Haemophilus influenzae and ß-lactams". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23211.pdf.

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11

Doloman, Anna. "Optimization of Biogas Production by Use of a Microbially Enhanced Inoculum". DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7531.

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A renewable energy source, biogas, comprises of methane (80%) and carbon dioxide (15%), and is a great alternative to the conventional fossil-based fuels, such as coal, gas and oil. Biogas is created during anaerobic biological digestion of waste materials, such as landfill material, animal manure, wastewater, algal biomass, industrial organic waste etc. A biogas potential from organic waste in the United States is estimated at about 9 million tons per year and technology allows capture of greenhouse gases, such as methane and carbon dioxide, into a form of a fuel. In the light of global climate change and efforts to decrease carbon footprint of fuels in daily life, usage of biogas as an alternative fuel to fossil fuels looks especially promising. The goal of this research was to develop and test an approach for optimization of biogas production by engineering microorganisms digesting organic waste. Specifically, bacteria that can digest algal biomass, collected from the wastewater lagoons or open waterbodies. The research also expands on the previous efforts to analyze microbial interactions in wastewater treatment systems. A computational model is developed to aid with prognosis of microbial consortia ability to form complex aggregates in reactors with upflow mode of feeding substrate. Combining modeling predictions and laboratory experiments in organic matter digestion will lead to more stable engineered systems and higher yields of biogas.

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12

Specht, Lawrence P. "Inoculum densities of Thielaviopsis basicola in tobacco fields in Virginia, and the relationship of inoculum density to the severity of black root rot and growth of tobacco". Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/49854.

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A new selective medium (TB-CEN) was developed for isolating Thielaviopsis basicola, cause of black root rot of tobacco, from soil. TB-CEN medium contains etridiazol and nystatin to inhibit the growth of undesired fungi, and unautoclaved extract from carrot to selectively enhance for the growth of T. basicola. Inoculum and/or population densities of T. basicola in five burley tobacco fields were 74-166 propagules per g of soil, and 0-12 propagules per g of soil in three other burley fields. Inoculum and/or population densities of T. basicola in 12 flue-cured and 2 sun-cured tobacco fields were 0-26 propagules per g of soil, and 101 and 402 propagules per g of soil in two other flue-cured fields. Environmental factors apparently had a strong effect on black root rot development, since root rot and plant stunting were severe in two burley fields that had 148 and 158 propagules per g of soil, but were not severe in the two flue-cured fields that had 101 and 402 propagules per g of soil. All of the cultivars planted in the four fields were susceptible. Black root rot was the major disease associated with the stunting of tobacco plants in the burley region of Virginia, but not in the flue- and sun-cured regions. No evidence was found to indicate that endomycorrhizae were involved in tobacco stunting in Virginia. T basicola inoculum density-disease severity studies were conducted both in soil-temperature tanks and in the field. Tobacco seedlings were grown in temperature tanks (20-23 C) for 30-31 days in naturally infested field soil (pH 6.5). For all cultivars tested (Burley 21, NC95, and Va Gold), the mean percent of roots that were rotted increased significantly (P=0.001) as inoculum density increased (R² range for regressions=0.93-0.97). Severe levels of root rot occurred at inoculum densities of 50-200 propagules per g of soil. Significant (P=0.01) reductions in plant growth occurred at inoculum densities as low as 5-10 propagules per g of soil. In a study conducted on a commercial burley tobacco (cv. B21-Ky10) field, inoculum densities of 150 and 683 propagules per g of soil were associated with moderate and severe levels of black root rot, respectively. Differences between soil-temperature tank and field studies appeared to be due to variations in environmental- and host-related factors. In another burley field study, the fungicide imazalil, which completely inhibited the growth of T. basicola when amended into agar media at a concentration of 1.0 μg a.i./ml, failed to control black root rot when it was added to transplanting water (50 ml/plant) at concentrations as high as 1,500 μg a.i./ml.
Ph. D.
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13

Karumanchi, Lakshmi. "Temperate region river sediments as a source of natural psychrophilic anaerobic inoculum". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92368.

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For psychrophilic anaerobic digestion systems, natural biota may provide sources of already adapted inoculum to reduce reactor start up time. The objective of the research was to test the inoculum potential of the microbial populations found in eight river sediments from the Montreal region, Canada, for the psychrophilic anaerobic digestion of swine manure. Also, to develop a simple theoretical method for quantification of acetoclastic methanogens in natural biota and validate using QRT-PCR technique. The anaerobic methanogenic populations of the sediments was quantified and characterized at 22 °C with specific methanogenic activity tests (SMA) using acetate and H2/CO2 as substrates. Then, biochemical methane potential (BMP) tests were conducted for 190 days at 10 °C using as substrate sterile swine manure, and as inoculums, the sediment with the highest methanogenic activity, fresh swine manure and sludge from an agro-food anaerobic mesophilic digester (AD sludge).
All eight sediments demonstrated pseudo-lag phases during the acetate SMA because of the low initial microbial populations. A visually significant correlation was observed between mgd.wt.cells/g sediment obtained from the predicted model and cell number/g sediment from the QRT-PCR results. During the H2/CO2 SMA, most sediments exhibited homoacetogenic activity out-competing that of the hydrogenotrophic methanogens. As compared to the most active sediment and swine manure and AD sludge inoculum presented approximately seven times more methanogenic activity at psychrophilic conditions. It also yielded 334 ml CH4/g CODin, which is almost twice as that of the active sediment. Further tests are required to optimize the process conditions, (i.e. loading rates, pH, etc.) in order keep the activity on its maximum.
Certaines biotes naturelles seraient en mesure de fournir aux systèmes de digestion anaérobie avec organismes psychrophiles des sources d'inoculum pré adaptés, réduisant ainsi le temps de démarrage du réacteur. L'objectif de cette étude fut d'évaluer le potentiel comme inoculum de populations microbiennes provenant de huit dépôts sédimentaires fluviaux de la région Montréalaise, pour la digestion anaérobie avec psychrophiles du lisier de porc. Il s'agirait aussi de développer une méthode théorique de base pour quantifier les méthanogènes acétoclastiques dans les biotes naturelles, et de la valider en utilisant une technique de transcription inverse suivie d'une PCR quantitatif en temps réel (QRT-PCR). Les populations anaérobies méthaniques des sédiments furent quantifiés et caractérisés à 22 °C grâce à des tests spécifiques d'activité méthanigène (SAM), utilisant l'acétate ou le H2/CO2 comme substrats. Des tests pour évaluer la production potentielle de méthane par voie biochimique (PPMB) se sont déroulés à 10 °C sur une durée de 190 jours, utilisant du lisier de porc stérile comme substrat, et comme inoculum soit (i) les sédiments ayant l'activité methanigène la plus élevée, (ii) du lisier de porc frais, ou (iii) de la boue de digesteur anaérobie (boue DA) de matières agroalimentaires.
Étant donné leur basses population microbiennes initiales, tous les sédiments présentèrent une pseudo phase de latence durant le test SAM avec l'acétate. Une corrélation visuelle significative fut notée entre le poids sec de cellules par grammes de sédiment (mg/g) prédite par la méthode théorique et celle obtenue par QRT-PCR. Lors du test SAM avec H2/CO2, la plupart des sédiments présentèrent une activité homoacétogène dépassant celle des méthanogènes hydrogènotrophes. Comparé au lisier de porc et à la boue DA, sous des conditions psychrophyliques le sédiment le plus actif a produit sept fois plus de CH4 par masse d'ATP. Aussi produisit-elle 334 ml CH4/g CODin, près de deux fois le rendement du sédiment actif. D'autres tests seront nécessaires pour optimiser les conditions opératoires (i.e., taux de charge, pH, etc.) afin de maintenir l'activité à un maximum.

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14

Schmechel, Detlef. "Development of an immunological approach to monitoring airborne inoculum of fungal pathogens". Thesis, Cranfield University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309712.

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15

Osborne, Josephine Frances. "Transmission of powdery scab disease of potatoes by seed tubers". Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311017.

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16

Barbi, Jose Henrique Tostes. "Use of the Rumen Simulation Technique (RUSITEC) to provide micro-organisms to assess in vitro rate of fermentation of forages". Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309503.

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17

Pamboukian, Celso Ricardo Denser. "Influência das condições de preparo do inóculo na morfologia do microrganismo e na síntese de glicoamilase por Aspergillus Awamori". Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-08082001-193604/.

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Neste trabalho foi estudada a influência da forma de preparo do inóculo na morfologia do microrganismo e na produção de glicoamilase por Aspergillus awamori, em cultivo submerso. Foram realizados ensaios variando-se a concentração de esporos utilizada no preparo do inóculo para o fermentador (pré-cultivo de células em incubador rotativo a 200 rpm e 35 oC, por 24 horas) no intervalo entre 9,5 exp 03 e 1,8 exp 07 esporos/mL. Os inóculos preparados com concentração de esporos entre 9,5 exp 03 e 9,5 exp 05 esporos/mL apresentaram-se na forma de uma suspensão de pellets e conduziram a um crescimento na forma filamentosa, em fermentador. A produção de glicoamilase, nos ensaios com concentração inicial de substrato de 40 g/L, realizados em fermentador, não foi influenciada pela concentração de esporos nessa faixa, mantendo-se entre 2100 e 2200 U/L. O aumento da concentração de esporos utilizada no preparo do inóculo para 1,8 exp 07 esporos/mL conduziu à formação de um inóculo na forma filamentosa contendo muitos aglomerados de esporos não germinados, que levaram a um crescimento, em fermentador, na forma de pellets, reduzindo a produção de glicoamilase para cerca de 1600 U/L e mostrando que o crescimento na forma de pellets não é indicado para a produção de glicoamilase. Foram estudadas, também, outras formas de preparo do inóculo, variando-se as condições de germinação dos esporos (pH e tempo de pré-cultivo do inóculo). A forma de preparo do inóculo que conduziu a uma maior produção de glicoamilase, em fermentador, foi o cultivo de esporos em incubador rotativo, a pH 2,5 durante 7 horas, o que evitou a aglomeração de esporos durante a etapa de germinação e a formação de pellets em fermentador, conduzindo a um crescimento na forma filamentosa e a uma alta produção de glicoamilase.
The influence of the inoculum preparation on Aspergillus awamori morphology and glucoamylase synthesis in submerged cultures has been investigated. A series of runs were performed, varying the spore concentration of the inoculum (inoculum size) in the range from 9.5 exp 03 to 1.8 exp 07 spores/mL. The inoculum was cultivated in shaker, at 35 oC and 200 rpm, for 24 hours. The inoculum prepared with a spore concentration in the range from 9.5 exp 03 to 9.5 exp 05 spores/mL was composed by a pellet suspension. This pellet suspension led to a filamentous growth in fermenter, but did not influence the glucoamylase production, which reached values from 2,100 to 2,200 U/L. The use of a higher spore concentration (1.8 exp 07 spores/mL) produced an inoculum composed by dispersed hyphae and many spores agglomerates, which led to pellet formation in the fermenter and reduced glucoamylase production to 1,600 U/L. Thus, pellet formation is not recommended in the process of glucoamylase synthesis. Some forms of inoculum preparation have been studied, varying spore germination conditions (pH and time of inoculum culture). The form of inoculum preparation that led to the highest glucoamylase activity in fermenter was the spore germination in shaker at pH 2.5 for 7 hours, which avoided pellet formation in the reactor and conducted to a high glucoamylase production.

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18

Gunalan. "Etude du comportement dans le sol d'un inoculum bactérien dégradant l'herbicide 2,4-D". Lyon 1, 1991. http://www.theses.fr/1991LYO10151.

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Pour verifier l'efficacite de l'inoculation d'une souche microbienne dans le sol, il est necessaire d'estimer a la fois la survie des micro-organismes et le maintien de leurs potentialites metaboliques. Un modele experimental a ete propose pour mieux connaitre ces deux aspects: il s'agit de l'utilisation d'une souche degradant un herbicide le 2,4-d. Le travail presente commence par une etude de la degradation du 2,4-d dans les sols naturels, par l'estimation de la taille des populations degradantes indigenes et par l'isolement des souches responsables. Quelques donnees concernant la microflore degradante de certains sols indonesiens sont egalement presentees au cours de cette premiere partie. Un micro-organisme alcaligenes xylosoxidans a ete retenu pour la suite de l'etude. La seconde partie presente des methodes permettant de faire varier les caracteristiques physicochimiques et biologiques du sol hote. La troisieme partie porte sur l'etude des principaux facteurs conditionnant l'efficacite de la souche introduite dans le sol. Quelques regles generales peuvent etre enoncees a partir des experimentations realisees: 1) la diminution de l'activite observee est due au mauvais etat physiologique de la souche maintenue dans un environnement oligotrophe (milieu de famine); 2) la perte d'efficacite serait liee a la competition entre organismes introduits et indigenes pour les sources de carbone disponibles dans le sol; 3) la predation ne semble pas a l'origine des effets observes; 4) l'apport de substrat carbone exogene peut restaurer l'activite metabolique d'une fraction de la population introduite prealablement dans le sol

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19

Barrett, E. y Phillip R. Scheuerman. "The Effect of Cell Inoculum Level and Substrate Concentration on p- cresol Degradation". Digital Commons @ East Tennessee State University, 1998. https://dc.etsu.edu/etsu-works/2914.

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20

Laveilhé, Arnaud. "Etude du potentiel d'un inoculum mixte dans l'amélioration de la santé du colza". Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0252/document.

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Le modèle de production agricole actuel est en pleine évolution. Là où jadis prévalaient volume et qualité des productions, les enjeux actuels intègrent de nouvelles exigences reposant sur l’éthique et le développement durable. La question n’est plus « comment produire plus » mais bien « comment produire plus efficacement ».Désormais, il n’est donc plus envisageable de dépendre uniquement de l’usage de produits phytosanitaires pour garantir un rendement suffisant des cultures. La sortie de cette dépendance passe par l’exploration de nouvelles voies d’amélioration basées sur des démarches scientifiques.Parmi les éléments de réponse proposés, l’axe exploré dans le cadre de ce travail repose sur l’amélioration de la compréhension des mécanismes mis en jeux au sein de la rhizosphère. Cette rhizosphère est le siège de nombreuses relations impliquant un bénéfice réciproque entre la plante et les populations microbiennes associées. Ces bactéries, appelées PGPR ont sur la plante de multiples effets bénéfiques qui seront détaillés dans ce travail.Un panel de sept souches bactériennes a été testé en interaction avec le colza dans le but d’évaluer sa réponse à l’inoculation. Ce travail a été complété par une étude sur l'expression des gènes phytobénéfiques de P. brassicacearum co-cultivé avec des champignons phytopathogènes et deux autres rhizobactéries en présence ou en l'absence de plante, et en fonction de la disponibilité du fer.La meilleure compréhension des mécanismes moléculaires régissant la rhizosphère permettra d’apporter de nouveaux éléments de réponse aux problématiques soulevées pas l’évolution des techniques de cultures
Agricultural production is changing. Now, this way of production includes new considerations as ethics and sustainable development. The main question is not any more “how to produce more” but “how to produce better?” The use of chemicals inputs cannot remain a solution to yield well and alternatives methods based on the recent scientific results are under investigation.One of these solutions is a better understanding of the mechanisms governing the microbial interactions in the rhizosphère. This soil fraction is characterized by an intense biological activity where plant and microorganisms interact. Beneficial microorganisms, called PGPR, are able to use root exudates as sole carbon and energy source and produce beneficial molecules stimulating directly or indirectly plant growth.Seven bacterial strains have been tested for their phytobeneficial abilities and their effect on rapeseed growth. The main objective of this study was to propose a mixt inoculum able to generate complementary phytobeneficial effects on rapeseed. Several trials have been carried out to evaluate the capacity of the inoculated strains to persist and grow in a non-sterile soil and their impact on the endogenous microbiota.This work has been completed by an evaluation of the expression of phytobeneficial genes in P. brassicacearum co-cultivated with plant pathogen fungi and two other rhizobacteria in presence or absence of plant, as well as in relation to iron availability.A better understanding of the microbial phytobeneficial mechanisms acting in the rhizosphere is a prerequisite of a successful application of microbial inoculation to face new challenges of modern agriculture

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21

Widmark, Anna-Karin. "The late blight pathogen, Phytophthora infestans : interaction with the potato plant and inoculum sources /". Uppsala : Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, 2010. http://epsilon.slu.se/201002.pdf.

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22

Bailey, Douglas John. "The role of inoculum in the primary and secondary infection of certain plant pathogens". Thesis, Open University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388433.

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23

Ordon, Violetta. "Field evaluation of fungal antagonists for the reduction of inoculum of Venturia inaequalis, Cke., Wint". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ50847.pdf.

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24

Ordon, Violetta. "Field evaluation of fungal antagonists for the reduction of inoculum of Venturia inaequalis (Cke.) Wint". Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21616.

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The use of a biofungicide on the perfect stage of V. inaequalis on leaf litter is one potential way to reduce the number of fungicides used to control apple scab. The previous in vitro screenings of Quebec mycoflora have shown that several isolates are able to significantly reduce the primary inoculum of the pathogen. Among the screened fungi, P176A and P130A, reduced over 98% of the ascospore production and were as effective as Athelia bombacina. However, because in vitro tests are generally poor predictors of in vivo assays a re-evaluation of the antagonists was done under field conditions. Eight fungal isolates, leaf shredding, and two comparative treatments (A. bombacina, 5% urea) were applied to intact scabbed leaves in October 1994 and 1995. After the treatments, the leaves overwintered on the orchard ground until the next spring. In April, samples of treated leaves were randomly selected and placed in spore traps to collect the ejected ascospores during rainfall. Since the primary inoculum was ejected during a four-month period, antagonism was based upon ratings taken throughout the whole ejection season. To evaluate the effect of incubation conditions on the antagonistic performance we incubated separately, in vitro and in vivo, sterile leaf disks which were artificially inoculated with V. inaequalis and fungal isolates. (Abstract shortened by UMI.)

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25

Ahmad, Norani. "Mycorrhizas in relation to Malaysian forest practice : a study of infection, inoculum and host response". Thesis, University of Aberdeen, 1990. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU548807.

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Surveys on the status of mycorrhizal infection and VAM propagules were carried out in 3 representative forest areas of Jengka in the Lowland Forest of Malaysia. VAM spore numbers found in these forest soils were low and well below those recorded in other tropical soils. However, levels of root infection in soil cores and infections in individual plant species were comparatively high. The assessment also confirmed the taxonomic dominance of VAM tree species in Malaysian forest. Regardless of the contrast between spore numbers and mycorrhizal root colonisation, evidence showed that current forest logging practices influenced significant changes in the infective VAM propagules. Propagules were reduced by 30 - 50&'37 when forest soils were severely disturbed through heavy soil mechanical compaction, exposure and erosion. Bioassay experiment using legume tree species suggested that the indigenous VAM propagules were infective but infection was closely related to the propagule density. Using Parkia speciosa and Albizia falcataria as test plant species it was further confirmed that low rates of infection by indigenous VAM fungi was a result of low inoculum density and doubling this inoculum increased infection levels. Between the indigenous VAM inoculum and the mixed introduced VAM inoculum, the latter proved to be more effective. For equal levels of infection of indigenous and introduced VAM, the mixed introduced VAM inoculum promote better plant growth in terms of plant height and shoot dry weight. With Intsia palembanica , the plant can be infected by either VAM or EM fungi or by both infections in the same root system. The species displayed a range of typical ectomycorrhizal structures which were similar to the etomycorrhizas of Dipterocarpaceae. Suitable inoculum for EM infection was widespread, even in sites where EM trees were absent. Even the Dipterocarp mycorrhizal fungi were able to initiate infection and growth response in Intsia plants. Inoculation experiments in Intsia , with EM and VAM fungi showed that both VAM and EM fungi increased P uptake initially. However, when the P in soil became exhausted, only VAM plants showed evidence of exploiting soil P, which was apparently not available to EM plants. In a subsequent pot trial, it was confirmed that mycorrhizal fungi enhance the growth of Albizia, Parkia and Intsia . These species were highly dependent on mycorrhizal fungi at seedling stage. P application however, showed negligible effect in growth enhancement, except at an optimum level of 4g P/pot. At this level of TSP applied, the interaction effects of mycorrhizal inoculation and TSP application were significant.

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26

Bortolini, Joseane. "Uso de diferentes inóculos na digestão anaeróbia da cama de aviário". Universidade Estadual do Oeste do Parana, 2016. http://tede.unioeste.br:8080/tede/handle/tede/266.

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Made available in DSpace on 2017-05-12T14:47:37Z (GMT). No. of bitstreams: 1 Josean_eBortolini.pdf: 1601181 bytes, checksum: 580412a5072cf9180422761979281cff (MD5) Previous issue date: 2016-02-12
The increasing population development has contributed to a significant increase in consumption and consequently poultry production, which results in a larger waste generation, since poultry litter receives excreta. One of the alternatives to treat waste and find a final disposal to it in this trial is the anaerobic digestion of poultry litter (PL), which not only generates bio-fertilizer, but also produces biogas. However, digester starting as well as quality and quantity of generated biogas are associated to the material to be digested and with the same operating conditions, since they are factors for inocula application. Thus, this study aimed to investigate the influence of digestate application as inoculum at anaerobic digestion from poultry litter. Firstly, specific biomethanogenic potential tests were carried out from poultry litter and there was a test to check if the digestate use as inocula has influenced on biogas production. Finally, this trial was carried out and inocula were tested (beef and swine digestate) during anaerobic digestion process of poultry litter, with daily diet, according to the volumetric loads that were tested - 0.67; 1.00; and 1.67 gSV.L-1day-1. It was concluded that poultry litter can be used as substrate in anaerobic digestion process and that digestate application as inoculum has shown adequate results regarding biogas production, since the treatment without inoculum addition showed the lowest biogas answers. So, when the inocula were compared with one another (beef and swine digestate), it was concluded that both of them are indicated in the digestion process with poultry litter. However, bovine inoculum showed the highest values of biogas and methane production, and also the lowest values in relation to the percentages of neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin (LIG), highlighting the advantages of its use as inoculum due to its greater capacity to degrade fibrous fractions.
O crescente aumento populacional contribui para o relevante aumento de consumo e consequentemente de produção de frangos, o qual acarreta maior geração de resíduos, pois a cama de aviário recebe as excretas. Uma das alternativas para o tratamento do resíduo e destinação final abordada neste trabalho é a digestão anaeróbia da cama de aviário (CA), que além de gerar o biofertilizante, produz o biogás. No entanto, tanto a partida do biodigestor como a qualidade e quantidade do biogás gerado estão relacionadas com o material a ser digerido e com as condições de operação do mesmo, os quais são fatores para a utilização de inóculo. Assim, o presente estudo teve como objetivo geral investigar a influência de aplicação de digestato como inóculos na biodigestão anaeróbia da cama de aviário. Para isso, inicialmente, foram realizados testes de potencial biometanogênico específico da cama de aviário e teste para verificar se o uso de digestato como inóculo influenciava a produção de biogás. Por fim, realizou-se o experimento e os inóculos foram testados (digestatos bovino e suíno) no processo de biodigestão anaeróbia da cama de aviário, com alimentação diária, conforme as cargas volumétricas testadas - 0,67; 1,00; e 1,67 gSV.L-1dia-1. Foi possível concluir que a cama de aviário pode ser utilizada como substrato no processo de biodigestão anaeróbia, assim como a utilização de digestato como inóculo apresentou resultados satisfatórios em relação à produção de biogás, uma vez que o tratamento sem adição de inóculo apresentou a menor média de produção de biogás. Em relação à comparação entre os inóculos, (digestato bovino e suíno), foi possível concluir que ambos são indicados no processo de biodigestão com cama de aviário. Contudo, o inóculo bovino apresentou os maiores valores em relação à produção de biogás e metano, e os menores valores em relação às porcentagens de fibra em detergente neutro (FDN), fibra em detergente ácido (FDA) e lignina (LIG), evidenciando as vantagens de sua utilização como inóculo em função de sua maior capacidade na degradação das frações fibrosas.

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27

Onudi, Benjamin Odhiambo. "Occurrance of wild grass geminiviruses in Kenya and their importance as sources of inoculum for maize". Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318092.

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28

Ben, Salem Olfa. "Étude de l'abondance relative de souches de "Fusarium graminearum" dans un inoculum mixte par séquençage 454". Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26066.

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Cette étude visait à suivre l’abondance relative d’une combinaison de quatre souches de Fusarium graminearum au cours du processus d’inoculation artificielle de parcelles d’orge. Trois amplicons présentant des polymorphismes (SSR, SNP) spécifiques ont été examinés par pyroséquençage 454 sur des échantillons récoltés à tous les stades (souches pures, mélange des souches, inoculum frais, inoculum au champ, grains d’orges infectés). Seuls les marqueurs SNP ont permis d’obtenir une signature unique à chaque souche et ont permis d’estimer l'abondance des souches dans chaque échantillon. Cette analyse a révélé qu’il était difficile d’obtenir des mélanges parfaitement égaux des souches et que les souches se développaient de manière inégale sur les grains de maïs servant de support à l’inoculum. Au champ, ces différences se sont largement maintenues, tandis que des profils d’abondance distinctifs sont apparus sur les trois sites d’essai chez les grains d’orge infectés, mais sans différences significatives entre les cultivars d’orge.
The aim of this study was to track the evolution of a combination of four Fusarium graminearum strains within a mixed inoculum and the ensuing stages of artificial inoculation on barley cultivars. Three amplicons containing specific polymorphisms (SSR, SNP) were examined by 454 pyrosequencing on samples collected at all stages of the process (pure strains, strain mixture, primary inoculum, inoculum in the field and infected barley kernels). Only SNP markers provided unique and accurate signatures for each strain. This analysis revealed that it was difficult to obtain perfectly equal mixtures of strains and that these strains differ in their development on corn kernels used as a growth medium for the inoculum. In the field, these differences remained, while distinctive abundance profiles were detected in infected barley kernels samples at the three nurseries; however, no significant differences between barley cultivars were observed.

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29

Barrett, E. y Phillip R. Scheuerman. "Effect of Inoculum level of a Freeze-Dried Consortium and Substrate Concentration on p-cresol Degradation". Digital Commons @ East Tennessee State University, 1998. https://dc.etsu.edu/etsu-works/2915.

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30

Cruz, Ivone Lopes. "Desenvolvimento de um inóculo seguro, eficiente e padronizado para a produção de tempeh em pequena escala a partir de diferentes leguminosas". Master's thesis, ISA, 2014. http://hdl.handle.net/10400.5/6799.

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Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia
Fermented foods from Eastern countries, based on crop fermentations are among the most desired by consumers for their nutrition value and potential as Functional foods and for their diversity and originality. Yet, these products are usually produced by spontaneous and poorly characterized fermentations under non-controlled conditions, which are not compatible with the high quality standards demanded by Western consumers. Tempeh is a popular Indonesian fermented food, originally based on soybean fermented by Rhizopus oligosporus. The objective of this work was to produce safer and effective Rhizopus oligosporus inocula and design standard procedures for safe and consistent tempeh production and conservation. Additionally new tempeh-like fermented products were also produced. Rhizopus oligosporus growth and inoculum preparation and inoculum concentration added to the crop, were optimized to obtain standard tempeh with the desired organoleptic properties. Adjustments on the production steps described for the traditional tempeh manufacture (soaking and fermentation parameters) were also made. Using the optimized procedures, a standard method for inocula and tempeh production was developed. Tempeh maintained its organoleptic properties when stored under vacuum in thermo sealed polypropylene bags and frozen until consumption. The production of several varieties of tempeh using different crops was accomplished under these conditions.

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Ballinas, Archundia Susana. "Effect of Saccharomyces cerevisiae on In Vitro Fecal Digestion of Four Feed Ingredients Commonly Used to Feed Horses in Mexico". Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2016. http://hdl.handle.net/20.500.11799/65150.

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ABSTRACT: The study aimed to assess the nutritive value in vitro of 4 feeds (grains and forages) commonly used in horses nutrition in Mexico, in the absence or presence of Saccharomyces cerevisiae at 4 mg/g DM. Fecal inoculum was obtained from 4 adult English Thoroughbred horses fed on restricted amount of concentrate and oat hay ad libitum. The incubated substrates included were corn gluten meal, soybean meal, oat grain and alfalfa hay. Gas production was recorded at 2, 4, 6, 8, 10, 12, 14, 24, 48 and 70 h using the Pressure Transducer Technique. Some ingredient × yeast interactions were observed (P < .020) for the asymptotic gas production (GP) and GP at 48 and 70 h of incubation. Yeast addition increased (P < .001) the asymptotic GP of concentrates compared to forages. Concentrate feeds had higher (P < .05) GP and lower (P < .001) rate of GP compared to forages without yeast. From 24 to 70 h of incubation, forages with or without yeast had lower (P < .05) GP compared to concentrates with yeast addition. Forages had higher fermentation pH compared to concentrates, but lower (P < .05) metabolizable energy (ME), in vitro organic matter digestibility (IVOMD) and microbial protein production (MBP) compared to concentrates. Yeast addition increased (P < .05) the asymptotic GP of oat grain and soybean meal, without affecting the rate of GP or lag time of both. Yeast treatment improved fermentation of feeds with higher effects on concentrates compared to forage. It was concluded that concentrate feeds had higher nutritive value than forages commonly fed to horses

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Petropoulos, Evangelos. "Investigating the true limits of anaerobic treatment of wastewater at low temperature using a cold-adapted inoculum". Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3021.

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Anaerobic batch reactors were inoculated with cold-adapted biomass (seed) to treat the organic material (COD) of domestic wastewater at 4, 8 & 15°C. The substrate was pre-UV sterilized to preclude competition between the cells thriving in the seed and the autochthonous, originated from wastewater cells. The performance in terms of organic removal showed that the specific cold-adapted inoculum efficiently treats anaerobically raw domestic wastewater at all temperatures based on the UWWTD (Urban Waste Water Treatment Directive) (91/271/EEC). The observed methanogenic taxa were Methanomicrobiales, Methanosaetaceae, and Methanosarcina during the whole experimentation. Methanomicrobiales were predominant at lower temperatures (4, 8°C) followed by Methanosaetaceae; at 15°C there was no distinct difference amongst them. Longer enrichment showed that further investigation may be required to clearly point the predominance between methanogens. Specific cellular activity was calculated (via qPCR, FISH) to enable scale-up & design simulation. The specific methanogenesis values showed that the activities at low temperatures are at least similar to those of typical mesophiles using a conservative cellular weighing reference to convert the cells to VSS. Higher specific activities were observed after acclimation of the cells at 4°C compared to 15°C regardless of the operational temperature (4 or 15°C). Acclimation at 4°C also resulted in a formation of a community that can be hardly disturbed from the competition of the wastewater cells when the seed:substrate ratio is low. This was not evident after acclimation at 15°C and it manifests that anaerobic treatment start-up at 4°C results in a sturdy and highly active methanogenic community. The CODRAW:CH4 conversion at 4°C was approximately 50% and reached up to 80% of the theoretically expected for sterile and non-sterile wastewater feed respectively. It is likely that the conversion was boosted from the synergy of the indigenous bacterial communities from wastewater and the cells originated from the seed. Enzymes (lipases) assays showed that the wastewater-originated group of cells (bacteria) contributed to the hydrolysis of insoluble organic material (lipids) and led to richer formation of intermediates that were subsequently utilized by the methanogenic populations of the seed. Limited lipid hydrolysis accounted for the organic material that remained insoluble. The lipases assays demonstrated that on equal temperatures (37°C) the specific activity of the enzymes secreted from the cells at low temperature (4°C) is higher than those secreted from cells at 15°C. This proves that the formation of a sturdier and of higher wastewater treatment performance community is likely when this is developed at low temperatures. The assay also demonstrated that a 4-degree temperature increase (from 4-8°C) is adequate to trigger the lipid:CH4 bio-conversion. Thus, for a complete anaerobic wastewater treatment using the specific inoculum, the temperature limit lies in-between 4°C and 8°C. A scale up designation based on the differentiation of the specific methanogenic activity according to temperature shouted that this limit lies at 5°C. For operation at lower temperature (<5°C), the required vessel volume and the hydraulic retention time (HRT) become extremely high and consequently financially unattainable. The results suggest that inoculating digesters for low temperature operation with cold-adapted communities is a promising way to treat wastewater and an appropriate solution for the investigation of the process limits. Hence, my recommendation for successful low temperature carbon neutral wastewater treatment is the inoculation of anaerobic reactors with cold adapted or psychrophilic biomass strategy, acclimation at low temperature and operation at a temperature >5°C.

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Hinks, Jamie. "Effect of inoculum on bioelectricity yield and the use of factorial experiments for assessing microbial fuel cells". Thesis, University of Newcastle Upon Tyne, 2012. http://hdl.handle.net/10443/1449.

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The study aim was to understand the effect of inoculum on bioelectricity production and the interactions that occur between organic load, external resistance and fuel type during the operation of a Microbial Fuel Cell (MFC). The first experiment explored the effect of four different environmental inocula (freshwater sediment, two types of return activated sludge (RAS) and anaerobic sludge) on microbial fuel cell performance. The number of bacteria in each of the inocula were standardised prior to experiments to achieve an inoculum density of 1.29 x 107cells ml-1 so that the comparison between treatments could be carried out fairly. For almost every metric (voltage, current and coulombic efficiency) the RAS inoculum outperformed freshwater sediment and anaerobic sludge inoculum. The treatment efficiency was high in all instances (>79%) with the exception of anaerobic sludge (33%). Microbial community analysis showed that anodes from MFCs exhibited a more complex microbial community profile than anodes from MFCs inoculated with anaerobic sludge. Two experiments were performed to investigate the relationship between fuel type, organic load and external resistance and their effects on MFC performance using an iterative Design of Experiments (DoE) approach. In the first experiment, a half factorial design was used as a screening study to investigate the main effects of fuel type (glucose vs acetate), organic load and external resistance. The study found that acetate performed poorly compared with glucose and that the experimental settings for external resistance should be modified for future experiments. The second experiment used a full factorial design and showed that only organic load exerted a statistically significant effect on cell potential, current and coulombic efficiency and that a statistically significant interaction effect between organic load and external resistance is exerted on cell potential and coulombic efficiency. The dominant effect of organic load was also apparent in DGGE community fingerprint profiles, which clustered according to organic load, of the anode community samples taken from MFCS in this study. In conclusion, the experiments yielded useful insights into inoculum effects and the interactions between basic operational parameters in an MFC that will be useful for selecting the operational parameters of MFCs depending on the field conditions and process requirements. The novelty of the techniques deployed in this study – standardisation the inoculum and exploring MFCs within a Design of Experiments framework – are noted along with the advances to our understanding of MFCs and the fact they have provided new tools with which to study MFCs systems. The wider implications of the performance characteristics of the MFCs used in this study and the findings presented within are discussed.

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34

Al-Hasani, Hamoud Darwish Salim. "Pathogenisty of Pythium aphanidermatum on greenhouse cucumber in Oman and strategies for management by reducing initial inoculum". Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401606.

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Povey, Jill Denise. "Investigation of approaches to assess the consequences of introduction of a genetically modified bacterial inoculum to soil". Thesis, University of Aberdeen, 1994. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU072995.

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This study was carried out as part of a contract funded by the Scottish Office to determine whether approaches to risk assessment, based on current recommendations, were adequate in determining the possibility of an adverse environmental effect of introduction of GMOs to the environment. The studies used a representative soil bacterium, Pseudomonas fluorescens, genetically modified by either chromosomal (FAC510) or plasmid (pUCD607) insertion of lux genes for bioluminescence. The starvation state is considered an important stress factor that bacteria added to soil may face. The ability to recover from this state, when substrates and nutrients become available, may be considered essential for the success of an introduced organism, and may ultimately determine the ecological effects of a GMO. The recovery response to the GMO constructs from carbon starvation was investigated in pure culture studies, and upon addition of starved cells to sterile soil. Pure culture studies clearly demonstrated a starvation-survival disadvantage of both the GMO constructs, as determined by growth and respiratory activity (dehydrogenase activity) when resuscitated from periods of starvation of up to 21 days. Correlation between dehydrogenase and luminescence activity was investigated. The lack of correlation between the two processes may have pointed to a change in maintenance energy costs as a consequence of genetic modification. Determination of the starvation-survival response in sterile soil was inconclusive, due to high variability and limitations to, and uncertainty in, cell extraction and culture.

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Hine, R. B., P. A. Mauk y Tesfaye Tedla. "The Effect of Soil Temperature and Inoculum Levels of Thielaviopsis basicola on Black Root Rot of Cotton". College of Agriculture, University of Arizona (Tucson, AZ), 1988. http://hdl.handle.net/10150/204546.

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Two planting dates, March 28, and April 28 were used to study the effect of soil temperature during planting on black root rot of cotton. Also, several cotton varieties were evaluated for response to the disease under varying soil temperatures and inoculum levels.

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Essiane, Ondo Olivier. "Caractérisation d'une collection de variétés anciennes de blé pour leur réponse à la mycorhization et impact sur la qualité du grain". Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS071/document.

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Le blé (genre Tritucum aestivum, famille des Poaceae) est une céréale d’intérêtagronomique très important. Certaines variétés très anciennes sont mise de côté pour desvariétés plus récentes souvent sélectionnées pour répondre à une culture intensiveconsommatrice de produits phytosanitaires. L’agriculture biologique, système de productionsupposant une réduction des intrants chimiques de synthèse afin de préserver l’écosystème,peut se définir comme une pratique où l’emploi d’engrais synthétiques, de pesticideschimiques et d’organismes génétiquement modifiés est prohibé.Cette pratique gagne de plus en plus en popularité et la superficie des terres cultivéesde cette manière a crû de 60 % entre 2000 et 2004, sur la planète. Les contraintes associées àla production de céréales biologiques comprennent la baisse de rendement attribuable auxcarences d’éléments nutritifs dans le sol et la concurrence des mauvaises herbes. Au cours des90 dernières années, les efforts internationaux d’amélioration du blé se sont concentrés sur lahausse du rendement et les paramètres de qualité.La mise en place d’une base de données des blé basées sur des critèresmorphologiques, taxonomiques et écologiques et l'introduction des mycorhizes à arbuscules(MA), connues pour aider à la sélection et induire une augmentation de rendement et dequalité de la production, dans l'optique de produire plus dans une agriculture respectueuse del’environnement pourrait constituer une partie intégrante d'une stratégie appropriée.Cependant, les effets mycorhiziens sur les rendement et la qualité de la production ne sont pastoujours prévisibles et les mécanismes qui régulent ces paramètres qualitatifs des mycorhizessont largement inconnus.Le criblage au champ de 53 variétés de blés anciens a montré des différences dans leuraptitude à développer des mycorhizes avec des champignons indigènes. Des plantesanalysées, seul cinq variétés étaient toutes mycorhizées au Tallage, alors que toutes l’étaientau stade Epiaison. Au stade Maturation des épis, dix-neuf variétés montraient une diminutionde la mycorhization.L’inoculation avec un inoculum de laboratoire lors de l’expérimentation en serre dansdes pots contenant d’une part leur terre habituelle de culture et de l’autre la terre d’Epoisses4montre, qu’ avec cet inoculum, toutes les variétés de blé se mycorhizent. Pour les variétéstestées, les variétés récentes utilisées en agriculture biologique mycorhizent mieux que lesanciennes, mais l’effet mycorhizien sur le rendement est observé uniquement chez desvariétés anciennes de blé. Démontrant ainsi un effet variétal sur le développement etl’expression de la symbiose. Les bénéfices de la symbiose sont plus accentués au niveau desphénomènes qualitatifs à savoir la viabilité des grains.L’apport d’un inoculum commercial lors d’expérimentation en serre dans des potcontenant le même sol, a modifié ces proportions. Cet inoculum a également permisl’amélioration du développement des blés et la qualité des graines de certaines variétésdémontrant à la fois l’importance du génome de la plante dans l’expression bénéfique de lasymbiose et de l’impossibilité des champignons mycorhizogènes indigènes à assurer ledéveloppement optimal de la symbiose. Au champ, l’effet variétal a été confirmé suite àl’apport d’un inoculum commercial ou, à l’exception d’une variété, l’inoculation a permis uneamélioration du rendement, particulièrement sensible chez la variété qui a été la plusproductive, soulignant l’intérêt qu’il y aurait à développer un projet de croisement pouraugmenter la réponse des blés aux mycorhizes
Wheat (kind Tritucum aestivum, Poaceae family) is a very important cereal ofagronomic interest. Some very ancient varieties are set aside for recent varieties often selected to meet a consumer intensive cultivation of pesticides. Organic farming production system assuming a reduction of synthetic chemical inputs in order to preserve the ecosystem can be defined as a practice where the use of synthetic fertilizers, chemical pesticides and genetically modified organisms is prohibited. This practice is gaining more and more popularity and the amount of land cultivated in this way has increased by 60% between 2000 and 2004. Constraints associated with the production of organic grains include lower yields due to nutrient deficiencies in the soil and weed competition. During the past 90 years, the international efforts in wheat breeding have focused on increasing yield and quality parameters The establishment of a wheat database based on morphological, taxonomic and ecological criteria and the introduction of arbuscular mycorrhizal (AM), known to help in the selection and induce an increase in yield and quality of production with a perspective to increase production in an agriculture that respects the environment, could be an integral part of an appropriate strategy. However, mycorrhizal effects on yield and quality of production are not always predictable and the mechanisms that regulate these qualitative parameters are largely unknown. Field screening of 53 ancient wheat varieties showed differences in their ability to interact with endogenous mycorrhizal fungi. Among the analysed plants, only five varieties were mycorrhized for all samples at tillering. All samples were mycorrhized at the heading stage for all varieties. Nineteen showed a decrease in the number of mycorrhized samples at the ears maturity. Inoculation with a laboratory inoculum during a greenhouse experiments in pots, containing either the wheat field soil or Ò EpoissesÓ soil, showed that all wheat varieties form mycorrhizal symbiosis. Between varieties tested, recent wheat varieties used in organic farming were better in forming symbiosis than the old, but the mycorrhizal effect on plant yield is seen only for old varieties. Demonstrating a variety effect on the development and 6 expression of symbiosis. The benefits of mycorrhizal symbiosis are more pronounced for the qualitative phenomena as the seed viability. The addition of a commercial inoculum in a similar greenhouse experiment modified these observations. This inoculum helped to improve wheat development but also the seed quality of some varieties, demonstrating both the importance of the plant genome in the beneficial expression of the symbiosis and the impossibility of indigenous mycorrhizal fungi to ensure optimal development of symbiosis. The previously observed field varietal effect was confirmed even after adding an exogenous inoculum as, excepted for one variety, inoculation has improved yield. This was especially noticeable in the variety that was most productive, stressing the importance to develop crossing strategies to increase the wheat response to mycorrhiza

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Naia, Inês Isabel Panasqueira. "Produção de alimentos funcionais inovadores a partir de tremoço e ervilha com base no método de produção de tempeh de soja". Master's thesis, ISA/UL, 2015. http://hdl.handle.net/10400.5/8547.

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Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia
Tempeh is an indonesian fermented food by the fungus Rhizopus oligosporus, which the production is beneficial as regards the improvement of the protein digestibility and nutritional value of legumes. The present work intended to optimize the production method of inoculum (R. oligosporus), while adding value to food industry (broken rice, wheat, corn and rye flours). The follow objective consisted in optimizing the production process of tempeh, using traditional Portuguese legumes (pea and lupine) in comparison with soy tempeh. Finally, texture parameters (firmness and cohesiveness) were evaluated by a TPA. Instrumental colour parameters, throughout the fermentation and after storage at refrigeration temperature were also evaluated. The results showed the viability of producing the inoculum using food industry by-products (5 days, 29 ° C), with rye, rice “carolino” and long grain rice flours yielding a higher sporulation. Soybean and pea tempeh complete fermentation after 48 h at 29 and 37 °C, respectively, while the lupine tempeh only after 72 h at 37 ° C. The highest values of firmness, cohesiveness and lightness (L *) were obtained at the end of fermentation. Significant variations in color, expressed in terms of a * and b * parameters, were observed

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GONZALEZ, BOBADILLA DANIA. "DETERMINACIÓN DE LA FUENTE DE INOCULO DE Claviceps gigantea PARA LA EXPRESIÓN DE DIENTE DE CABALLO EN EL HIBRIDO FAISÁN". Tesis de Licenciatura, UNIVERSIDAD AUTÓNOMA DEL ESTADO DE MÉXICO, 2020. http://hdl.handle.net/20.500.11799/108777.

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The incidence and damage caused by the fungus Claviceps gigantea has increased considerably in the Toluca Valley region. It has been reported in fields of susceptible maize hybrids at altitudes from 2,000 to 2,800 masl, especially in plots under high productivity programs. The objective of this study was to identify the source of the inoculum leading to the expression of Claviceps gigantea in the Faisán® hybrid, evaluating different concentrations of ascospores and microconidia (500,000; 250,000; 100,000 and 50,000). The study consisted of two stages. The first was performed in the laboratory, to obtain solutions at the different experimental doses, and the second was performed in the field, where plants that were considered ideal for inoculation were inoculated using the injection technique. For each inoculum type and concentration, 5mL were injected per plant. The results showed that the source of inoculum was ascospores, and 100,000 was the dose that led to the highest incidence and most severe degree of horse’s tooth; the incidence of ears affected increased by 50%, and sclerosis formed by 40 days. Thus, this type of spore demonstrated an ability to generate a new inoculum, reproductive structures, and/or spores in a shorter time period.

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Gulez, Gamze. "Short Term Effects of Carbon and Inoculum Sources on Filamentous Growth: A Comparison between Molecular and Microscopic Methods". NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-05182005-214310/.

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Filamentous bulking in activated sludge treatment plants is a worldwide problem. Understanding the growth requirements of specific filamentous organisms will allow the development of better control strategies for bulking. In this study, the short term effects of eight carbon sources and three inoculum sources on the growth of filamentous bacteria were tested. Three lab scale sequencing batch reactors (SBR) were operated. Microscopic (Gram and Neisser staining) and molecular methods (Denaturing Gradient Gel Electrophoresis [DGGE], Fluorescent in Situ Hybridization [FISH]) were used to track the microbial population changes in the reactors. Sludge volume index (SVI) measurements were used to monitor bulking in the reactors. DGGE and sequencing results indicated the presence of the filamentous bacteria Sphaerotilus natans and Thiothrix. S. natans grew in glucose-, acetate-, and sucrose-fed reactors, regardless of the inoculum source. It also grew in propionate- and pyruvate-fed reactors inoculated with the sludge from the Neuse River Wastewater Treatment Plant (WWTP). Thiothrix was detected in propionate- and pyruvate-fed reactors inoculated with sludge from the South Cary WWTP, and in glucose- and acetate-fed inoculated with the sludge from the Neuse River WWTP inoculated reactors. In addition to these two filaments, Gram and Neisser staining indicated the presence of Nostocoida limicola in Neuse River WWTP inoculated reactors. The presence of S. natans and T. nivea was confirmed with FISH. SVI measurements were consistent with the level of bulking, showing an increase as the number of filaments in the reactors increased. This study confirmed that readily biodegradable substrates favored the growth of S. natans, T. nivea and, N. limicola in activated sludge. The simultaneous use of microscopic and molecular tools provided the information above with one method compensating for the other method?s biases.

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Dung, Jeremiah Kam Sung. "Relative roles of tuber- and soilborne inoculum in verticillium wilt of potato and quantification of resistance in mint". Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Spring2009/j_dung_042509.pdf.

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42

Suwannoppadol, Suwat. "Rapid Start-up of batch thermophilic anaerobic digestion and overcoming sodium toxicity by utilizing turf grass as inoculum". Thesis, Suwannoppadol, Suwat (2012) Rapid Start-up of batch thermophilic anaerobic digestion and overcoming sodium toxicity by utilizing turf grass as inoculum. PhD thesis, Murdoch University, 2012. https://researchrepository.murdoch.edu.au/id/eprint/20875/.

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Thermophilic anaerobic digestion offers certain advantages over mesophilic anaerobic digestion such as a higher rate of biogas production and significant pathogen reduction. Despite such advantages, there remain some key hurdles preventing the wider adoption of thermophilic digestion, one of them being that of a difficult start up procedure. To overcome this limitation, this thesis aims to determine suitable start-up conditions and inoculum sources suitable for thermophilic anaerobic digestion. Cow manure, a well-known source of methanogens, was compared to municipal solid waste (MSW) as seeds for of thermophilic anaerobic digestion start-up. Results indicated that in contrast to cow manure, MSW (collected from the metropolitan area of Perth, Western Australia) has a higher potential to be a thermophilic anaerobic seed as compared to cow manure. After incubating of MSW at 55 ˚C, methane was produced within 3 days with an initial methane production rate of 0.7 L*L-1*day-1. In an attempt to narrow down the source of thermophilic methanogens in a typical MSW, components of a typical MSW (vacuum cleaner dust, banana peel, kitchen waste, and garden waste), which might contain the thermophilic methanogens, were tested as inoculum for thermophilic methanogenesis with acetate as the substrate. Results singled out grass turf as the key source of thermophilic acetoclastic methanogens. Within 4 days of anaerobic incubation at 55oC, anaerobically incubated grass turf samples produced methane accompanied by acetate degradation enabling the successful start-up of thermophilic anaerobic digestion. This indicates that turf has the ability to act as an alternative seed for the start-up of thermophilic anaerobic digestion. Theoretically, methanogens could be divided into two main groups: hydrogenotrophic and acetoclastic methanogens. Hydrogenotrophic methanogens generate methane from the reduction of carbon dioxide by utilizing hydrogen as an electron donor while acetoclastic methanogens cleave acetate to form methane and carbon dioxide. Therefore, investigation of both groups of methanogens in each fraction of turf was addressed in the current study. Characterization of the incubated turf sample identified the main hydrogenotrophic and acetoclastic methanogens present in turf to be Methanoculleus sp. and Methanosarcina sp. respectively. The current study also investigated the effects of co-digestion of grass leaves in anaerobic digestion on sodium toxicity. It was motivated by results of observations that with appropriate addition of sodium bicarbonate (330 mM), to tackle the early build-up of volatile fatty acids, successful start-up of MSW and grass leaves were established. A study was conducted to evaluate to what extent grass leave) could help in overcome the sensitivity of methanogenic populations to high sodium content. Results demonstrated the complete failure of the start-up of thermophilic anaerobic digestion at sodium concentration of 7.8 g Na+/L. Grass leaves addition could, however, reduce the effects of sodium toxicity in both mesophilic and thermophilic digestion. Moreover, in an attempt to narrow down the component of grass leaves which is responsible for elevating sodium toxicity, different likely compounds present in grass leaves such as potassium and betaine were tested. Results revealed that addition of betaine (GB) (1, 5, 10 mM) was observed to be effective in increasing methane production in the presence of high sodium. To correlate the effect of GB to the effect caused by grass leaves, the GB content in the turf grass was determined. Results of betaine analysis showed that there was 3.9 mg of GB present per g of fresh grass leaves, resulting in final expected GB concentration of 3.3 mM. This implies that GB is one of the organic compounds contained in grass leaves, which plays an important role in the antagonistic effect of grass leaves toward sodium toxicity during thermophilic anaerobic digestion.

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OLIVEIRA, Michelle Jardelina de. "Epidemiologia da podridão-de-fusário em frutos de meloeiro". Universidade Federal Rural de Pernambuco, 2007. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6633.

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Made available in DSpace on 2017-03-22T14:15:27Z (GMT). No. of bitstreams: 1 Michelle Jardelina de Oliveira.pdf: 626765 bytes, checksum: 09ece639b4aa984e06e818a82994095a (MD5) Previous issue date: 2007-03-14
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
The Fusarium rot, caused by the fungus Fusarium pallidoroseum, is an important postharvest disease of melon (Cucumis melo) fruits in the Brazil. This work aimed to analyze the influence of the inoculation method (pulverization, drop deposition, pulverization with wound, drop deposition with wound, and sub-epidermal injection), wound age (0, 12 and 24 hours), humidity (with and without moist chamber), temperature (10, 15, 20, 25, 30 e 35°C) and inoculum concentration (101, 102, 103, 104, 105, 106 conidia/mL-1) of three F. pallidoroseum isolates (CF-589, CF-685 and CF-687) on the severity of the Fusarium rot in melon fruits type Cantaloupe (cv. Torreon) and Honeydew (cv. Orange Flesh). The three F. pallidoroseum isolates had provoked symptoms of Fusarium rot in the evaluated situations, but they had not differed significantly (P=0,05) between itself how much to the severity levels of disease, as well as had not been evidenced significant interactions with melon’s cultivars. On the other hand, in all the experiments had been evidenced significant differences in the disease levels between two melon’s cultivar, with cv. Torreon presenting levels of disease’s severity significantly higher to the evidenced on Orange Flesh cultivar. It did not haveseverity significantly higher to the evidenced on Orange Flesh cultivar. It did not have development of injuries in the fruits when the inoculations had been carried without wound. The inoculation for atomization of the conidia’s suspension propitiated the biggest injuries in the submitted fruits at wounds. The inoculation for sub-epidermal injection caused lesser injuries than methods of atomization or drop with wound. It had the reduction of the severity of the disease in the fruits with the increase of the age of the wound. The injuries had been significantly lesser in the wounded fruits 24 hours before the inoculation than in those wounded fruits with 12 hours before or immediately before the inoculation. The free water presence in the surface of the fruits was unnecessary for the beginning of the infection’s process for F. pallidoroseum isolates, even so the injuries has been bigger in the fruits submitted to the humid chamber. The temperature significantly influenced the severity of the Fusarium rot, being that the optimum temperatures estimated for the disease’s development were 23,9 °C e 23,0 °C, respectively for Orange Flesh e Torreon cultivar. The severity of the disease increased with the increment in the inoculum concentration of F. pallidoroseum. The biggest injuries had been observed in the concentration of 1x106 conidia/mL-1 in the twocultivars, but same in lesser inoculum concentration (1x101 conídios/mL-1), they registered considerable levels of disease. The inoculum concentration necessary to generate 50% of the maximum size of the injury Orange Flesh cultivar was four times higher than that demanded for Torreon cultivar.
A podridão-de-fusário, causada pelo fungo Fusarium pallidoroseum, é uma importante doença em pós-colheita de frutos de meloeiro (Cucumis melo) no Brasil. Este trabalho teve como objetivos avaliar a influência dos métodos de inoculação (atomização, gota, atomização com ferimento, gota com ferimento e injeção subepidérmica), da idade do ferimento (0, 12 e 24 h), da umidade (sem e com câmara úmida), da temperatura (10, 15, 20, 25, 30 e 35 °C) e da concentração de inóculo (1x101, 1x102, 1x103, 1x104, 1x105 e 1x106 conídios.mL-1) de três isolados de F. pallidoroseum (CF-589, CF-685 e CF-687) na severidade da podridão-de-fusário em frutos de meloeiro dos tipos cantaloupe (cv. Torreon) e honeydew (cv. Orange Flesh). Os três isolados de F. pallidoroseum provocaram sintomas da podridão-de-fusário nas situações avaliadas, mas não diferiram significativamente (P=0,05) entre si quanto aos níveis de severidade da doença, bem como não foram constatadas interações significativas com as cultivares de meloeiro. Por outro lado, em todos os experimentos foram constatadas diferenças significativas nos níveis de doença entre as duas cultivares de meloeiro, com a cultivar Torreon apresentando níveis de severidade da doença significativamente superiores aos constatados na cultivar Orange Flesh. Não houvedesenvolvimento de lesões nos frutos quando as inoculações foram realizadas sem ferimento. A inoculação por atomização da suspensão de conídios propiciou as maiores lesões nos frutos submetidos a ferimentos. A inoculação por injeção subepidérmica ocasionou lesões menores que os métodos de atomização ou gota com ferimento. Houve a redução da severidade da doença nos frutos com o aumento da idade do ferimento. As lesões foram significativamente menores nos frutos feridos 24 horas antes da inoculação do que naqueles feridos com 12 horas antes ou imediatamente antes da inoculação. A presença de água livre na superfície dos frutos foi desnecessária para o início do processo de infecção pelos isolados de F. pallidoroseum, embora as lesões tenham sido maiores nos frutos submetidos à câmara úmida. A temperatura influenciou significativamente a severidade da podridão-de-fusário, sendo que as temperaturas ótimas estimadas para o desenvolvimento da doença foram 23,9 °C e 23,0 °C para Orange Flesh e Torreon, respectivamente. A severidade da doença aumentou com o incremento na concentração de inóculo de F. pallidoroseum. As maiores lesões foramobservadas na concentração de 1x106 conídios.mL-1 nas duas cultivares, mas mesmo na menor concentração de inóculo (1x101 conídios.mL-1) foram registrados consideráveis níveis de doença. A concentração de inóculo necessária para gerar 50% do tamanho máximo da lesão na cultivar Orange Flesh foi mais de quatro vezes superior à exigida pela cultivar Torreon

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44

Baza, García Luis Angel. "In Vitro Assessment of Fecal Inocula From Horses Fed on High-Fiber Diets With Fibrolytic Enzymes Addition on Gas, Methane and Carbon Dioxide Productions As Indicators of Hindgut Activity". Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2016. http://hdl.handle.net/20.500.11799/65147.

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This study was aimed to assess the effect of fecal inocula from horses fed on concentrate (restricted amount daily) and oat straw (ad libitum) supplemented with fibrolytic enzymes on in vitro hindgut activity. Cellulase (CE), xylanase (XY) and CE+XY (1:1 v/v; CX) were tested at three levels (μL/g DM): 0, 1 and 3, in addition to control without enzyme addition (EP0). Fecal inocula were collected from 16 Quarter Horse mares supplemented with enzyme at 0 (FCOwithout enzyme), or fed 10 ml enzyme/mare/day of CE (FCE), XY (FXY) or CE+XY (1:1 v/v; FCX) for 15 days. The fecal content mixed with the culture media were used for incubation in bottles containing 1 g DM of substrate (a mixture of concentrate and oat straw (1:1 DM)). Gas (GP), methane (CH4) and carbon dioxide (CO2) productions were measured at 2, 4, 6, 8, 10, 12, 24 and 48 h post-incubation. Interactions occurred (P˂0.05) between fecal type × enzyme product for the asymptotic GP, the rate of GP, CH4 production, and fermentation kinetic parameters. Moreover, interactions were observed (P˂0.05) between fecal type × enzyme product × enzyme dose for the rate of GP, CH4 production and DM digestibility. Xylanase at 3 μL/g DM with FXY fecal increased (P˂0.05) the asymptotic GP and calculated fermentation parameters. At 24 h and 48 h and without enzyme, FCX and FXY, respectively, had the highest (P˂0.05) CH4 production. It can be concluded that xylanase enzyme at 3 μL/g DM was the most effective compared to other treatments.

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45

Bujold, Isabelle. "The use of a fungal antagonist to reduce the initial inoculum of Gibberella zeae on wheat and corn debris /". Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31199.

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Gibberella zeae (anamorph: Fusarium graminearum) is the causal agent of fusarium head blight (FHB) and maize ear rot, two major diseases of wheat and corn in Eastern Canada.
In Quebec, Microsphaeropsis sp., an antagonist of Venturia inaequalis, the causal agent of apple scab, was isolated from the apple leaf litter. This fungus, well adapted to Quebec climate, can reduce the initial inoculum of V. inaequalis. FHB and Gibberella ear rot are similar to apple scab because the major inoculum source comes from melanized structures produced on crop residues. Consequently, we evaluated the potential of Microsphaeropsis sp. (isolate P130A) to inhibit ascospore production of G. zeae when applied to crop residues as post harvest or pre-planting applications. Under in vitro conditions, the antagonist significantly reduced ascospore production on wheat and corn residues, when applied prior to (82% and 92% respectively) or at the same time as the pathogen (36% and 58% respectively). Under field conditions, the antagonist had no effect on the pattern of perithecia maturation but significantly reduced the number of ascospores produced on two sampling dates, May 1998 and July 1999. (Abstract shortened by UMI.)

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46

Mudita, I. Wayan. "Production of Conidia, selection of inoculum density, and timing the first fungicide application to manage Septoria blight of celery". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61038.

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Septoria blight of celery (Apium graveolens var. dulce), induced by Septoria apiicola Speg., is a destructive disease that requires fungicide applications for its management. A reliable method of inoculum production was established. Best sporulation was obtained on celery agar (CA) at a predicted optimum temperature of 22.4$ sp circ$C. A moderate inoculum density within a range of 17-35 conidia/cm$ sp2$ of leaf surface provided non-coalescing lesions necessary for rapid enumeration. Initial blight incidence thresholds of about 0.6 and 0.5% to time the first fungicide application were established based on the proportion of maximum plant weight equivalent to the cost of one fungicide application calculated plant weight and petiole number per plant, respectively, in the summers of 1990 and 1991. The IBI levels of 0 and 2% to time the first fungicide application provided non-significant results in terms of the final amount of blight and yield. (Abstract shortened by UMI.)

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47

Keller, Melissa Dawn. "The Contribution of Within-Field Inoculum Sources of Gibberella zeae to Fusarium Head Blight in Winter Wheat and Barley". Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/27565.

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Fusarium head blight (FHB) is one of the most economically important diseases of small grains and continues to impact crops when environmental conditions are favorable to Gibberella zeae (Fusarium graminearum), the causal agent of the disease. Corn residues are considered to be primary sources of inoculum for epidemics of FHB. Therefore, knowledge of the movement of Gibberella zeae from a local source of infested corn residue is critical to the management of FHB in wheat and barley. Previous research made significant progress in defining the spatial dissemination of inoculum sources of G. zeae within agricultural fields, but was unable to clearly distinguish between within-field and background sources. Using amplified fragment length polymorphism, released clones of G. zeae were tracked within wheat and barley fields. This strategy allowed the distinction between the contributions of released clones to FHB, compared to that of background inocula. Corn residue infested with clones of G. zeae was placed into small replicated plots in winter wheat fields in New York and Virginia in 2007 and 2008 and wheat spikes were collected at 0, 3, 6, and â ¥24 m from the inoculum sources. Recovery of released clones decreased an average of 90% between 3 and 6 m from inoculum sources. Various amounts of corn residue infested with a single clone of G. zeae were placed into small replicated plots in winter wheat and barley fields in Virginia from 2008 to 2010. The use of minimal or conventional tillage and a moderately resistant cultivar of wheat or barley may reduce the contribution of within-field inocula to FHB; however, environmental conditions play an important role in the effectiveness of these management strategies. With the increase of corn production due to incentives for ethanol-based fuel, overwintering sites for G. zeae on corn residue are likely to increase. Our work contributes to an increased understanding of the influence of overwintered corn residue to FHB which will also direct future research on how to reduce the inoculum potential from within-field sources.
Ph. D.

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48

Larson, William Kalvin. "The Effect of Variable Seed-Borne Inoculum Load of Dickeya dianthicola on Performance and Infection of Field Grown Potatoes". Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/32039.

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Field experiments were conducted at Live Oak, Florida, and Rhodesdale, Maryland, to evaluate the effect of variable seed-borne inoculum load of Dickeya dianthicola on potato plant emergence, plant growth throughout the growing season, disease prevalence in the field throughout the growing season, yield and grade, and transmission of D. dianthicola to progeny tubers. No statistically significant differences in emergence, plant height, or disease incidence were observed at either location. Statistically significant differences were observed in yield at the Florida location; all inoculated treatments had significantly lower yield than the non-inoculated control. No significant differences in yield were observed among treatments at the Maryland location. No significant differences in grade were observed at the Florida location. Significant differences in one tuber profile category were observed at the Maryland location. No significant differences in transmission of D. dianthicola to progeny tubers were observed at the Florida and Maryland locations.

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49

Yamada, Jaqueline Kiyomi. "Inoculum dynamics of Ralstonia spp.: potential sources, persistence in a local population and selection of phages to reduce bacteria survival". Universidade Federal de Viçosa, 2018. http://www.locus.ufv.br/handle/123456789/22454.

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Ralstonia spp. são conhecidas por causar murcha bacteriana em várias plantas de interesse econômico. O patógeno possui alta variabilidade genética, ampla variedade de hospedeiros e pode sobreviver no solo mesmo na ausência de hospedeiros. A compreensão das potenciais fontes de inóculo, que contribuem para a variabilidade genética no centro de origem do patógeno é interessante para o manejo da doença. O papel dos rios, plantas daninhas e da população nativa de Ralstonia spp. em áreas de vegetação natural no desenvolvimento de epidemias de murcha bacteriana é pouco compreendido. A variabilidade genética entre cepas de Ralstonia spp. em uma região onde a doença é endêmica pode elucidar a contribuição dos meios de dispersão e fatores associados à sobrevivência. No presente estudo, a detecção de Ralstonia spp. em rios de diferentes biomas do Brasil revelou o potencial destes recursos naturais para dispersar o patógeno. As plantas invasoras mostraram ser importantes reservatórios de ambas as espécies de Ralstonia que ocorrem no Brasil e colaboram para sua sobrevivência. Métodos de detecção não foram sensíveis para confirmar a presença de Ralstonia spp. em amostras de solo de áreas sem ocorrência de murcha bacteriana. Quando se analisaram 204 isolados de R. solanacearum e 60 isolados de R. pseudosolanacearum obtidos do município de Coimbra, Minas Gerais, constatou-se haver baixa variabilidade genotípica e clonalidade. Nenhuma estruturação foi observada para as regiões do município, mas a composição genotípica variou entre os anos amostrados. Para o controle alternativo da murcha bacteriana, cinco fagos pertencentes à família Siphoviridae, ordem Caudovirales, foram isolados em amostras de solo. A análise molecular e a gama de hospedeiros com diferentes isolados de Ralstonia spp., representando o Brasil, revelaram diferenças entre os vírus. Adicionalmente, houve diferenças quanto à gama de hospedeiros quando os cinco fagos foram expostos a 24 isolados de Ralstonia spp. Os fagos não foram capazes de prevenir a infecção e controlar o número de células de Ralstonia spp. no solo. Outros métodos de aplicação são necessários para avaliar a eficiência dos fagos no controle da murcha bacteriana.
Ralstonia spp. are known to cause bacterial wilt in several plants of economic interest. The pathogen has high genetic variability, wide host range and can survive in the soil even in the absence of hosts. Understanding potential inoculum sources that contribute to genetic variability in the center of origin is interesting to the management of the disease. The importance of rivers, weeds and native population of Ralstonia spp. in areas of natural vegetation in the development of epidemics of bacterial wilt is poorly understood. Genetic variability among strains of Ralstonia spp. in a local region where the disease is endemic can elucidate the contribution of the means of dispersal and factors of survival. In the present study, the detection of Ralstonia spp. was attempted in water of rivers of different biomes of Brazil and revealed the potential of these natural resources to disperse the pathogen. Weeds were important reservoirs of both species of Ralstonia that occur in Brazil, and collaborate to their survival. Methods of detection were not sensitive to confirm the presence of Ralstonia spp. in soil samples from areas without the occurrence of bacterial wilt. The genetic variability of 204 strains of R. solanacearum and 60 strains of R. pseudosolanacearum from the municipality of Coimbra, Minas Gerais, was low and there was evidence of clonality in the population. The population was not genetically structured according to the geographic region in the municipality, however the genotypic composition varied in time. To assess an alternative measure to control bacterial wilt, five phages were isolated. All phages belong to the Siphoviridae family, Caudovirales order. Molecular analysis and host range with different R. solanacearum strains revealed differences among the viruses. There were differences in the host range when the five phages were exposed to 24 Ralstonia spp. strains. The phages were not able to prevent tomato infection and control the number of cells of Ralstonia spp. in the soil. Other methods of application are necessary to evaluate the efficiency of the phages to control of bacterial wilt.

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50

Lallemand, Elodie Anne. "Impact de la taille de l'inoculum bactérien sur l'efficacité d'un traitement antibiotique : développement d'un modèle in vitro associant bactéries, antibiotiques et cellules du système immunitaire inné". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30076/document.

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Dans un contexte d'usage raisonné des antibiotiques lié au développement des résistances bactériennes, il est pertinent de chercher à optimiser les profils d'exposition plasmatique qui conduiraient à la meilleure efficacité de l'antibiotique sur les bactéries pathogènes. La charge bactérienne n'est pas stationnaire tout au long du développement d'une infection, mais elle augmente spontanément ou diminue avec un traitement antibactérien efficace. L'objectif de cette thèse était d'évaluer l'influence de la variation de la charge bactérienne sur l'efficacité des antibiotiques et du système immunitaire.Au cours d'un premier travail, nous avons montré que dans les conditions de réalisation de tests de sensibilité in vitro (détermination de CMI), une dégradation de certains antibiotiques se produisait, d'amplitude variable selon les molécules testées. Cette dégradation peut être responsable d'une augmentation des valeurs de CMI et de CMB. Les variations observées étaient cependant inférieures à une dilution au demi dans une gamme de concentrations. Cette dégradation ne devrait pas avoir d'impact significatif sur les résultats des tests de sensibilité aux antibiotiques concernés, excepté dans des cas particuliers comme des pathogènes à croissance très lente. Dans un deuxième travail, nous avons étudié in vitro chez E. coli et S. aureus l'effet de la taille de l'inoculum bactérien sur l'activité bactéricide de 2 céphalosporines, la céphalexine et le cefprozil. Nous avons observé une diminution de l'activité bactéricide des 2 céphalosporines avec l'augmentation de la taille de l'inoculum chez E. coli et S. aureus. Nous avons également montré une efficacité et une puissance moins importante des 2 céphalosporines sur S. aureus par rapport à E coli.Dans un troisième temps, nous avons développé un système incluant les trois composantes suivantes : une bactérie - S. aureus -, des cellules du système immunitaire - des macrophages murins issus de la moelle osseuse - et un antibiotique -la céphalexine-. Dans ce système, nous avons fait varier la taille de l'inoculum bactérien de départ ainsi les concentrations en antibiotique. Une augmentation de la phagocytose bactérienne et de la mortalité des macrophages ont été observées avec l'augmentation de la charge bactérienne. L'activité bactéricide des macrophages était saturable et en présence d'une charge bactérienne trop importante, une partie des macrophages sont devenus un réservoir de S. aureus phagocytés. En présence de la céphalexine, qui a une distribution exclusivement extracellulaire, les quantités de bactéries extracellulaires, " candidates " à la phagocytose, ont diminué. Ainsi, en présence de céphalexine et pour les charges bactériennes initiales les plus faibles, les capacités de survie et de bactéricidie des macrophages ont été préservées. Cette action n'a cependant plus été visible en présence de gros inocula bactériens pour lesquels l'action limitée de la céphalexine n'a pas permis de prévenir la saturation des macrophages et ses conséquences. Le modèle à trois composantes que nous avons développé constitue une première étape dans le développement de modèles in vitro qui associent des éléments de l'immunité innée aux modèles pharmacologiques classiques bactéries/antibiotiques, avec l'objectif d'optimiser l'évaluation préclinique de molécules antibactériennes
As one of the current pre-eminent public health concerns is to reasonably use antibiotics in order to limit antibacterial resistance development, it appears relevant to determine the plasmatic exposition profile that would lead to the best efficiency of the antibiotic on pathogenic bacteria. The bacterial load is not stationary during an infection but it increases or decreases with an effective antibiotic treatment. The aim of this thesis was to evaluate the influence of variation of the bacterial load on antibiotic and immune system activity.First, we showed that during antibacterial sensibility tests, such as standard MIC determination, some antibiotics underwent abiotic degradation during incubation, with a magnitude depending on the drug tested. This degradation can increase MIC and MBC values. However, the observed discrepancy (less than one twofold dilution) suggests that this would only be clinically significant in special cases such as slow-growing bacteria.Then, we studied, with E. coli and S. aureus, the in vitro effect of the bacterial inoculum size on bactericidal activity of 2 cephalosporins, cephalexin and cefprozil. We observed a decrease of bactericidal activity of both cephalosporins with an increase of the initial inocula of E. coli and S. aureus. A decreased efficacy and potency of the 2 cephalosporins against S. aureus compared to E. coli was also found. Finally, we developed an in vitro 3-components model including a bacterium -S. aureus-, cells of the immune system -murine bone-marrow-derived macrophages- and an antibiotic -cephalexin-. Within this system, we tested several initial bacterial inoculum sizes and different antibiotic concentrations. Increased bacterial phagocytosis and macrophage mortality were observed with increasing bacterial inocula. Bactericidal activity of macrophages was saturable and faced to a large bacterial inoculum, some macrophages became a reservoir for living S. aureus. With cephalexin, which is an extracellular antibiotic, extracellular bacteria diminished over time implying a diminution of the bacteria to be phagocytosed by macrophages. Thus, macrophages bactericidal and survival abilities were preserved with cephalexin and small bacterial inocula. This effect of the antibiotic was no longer visible with highest bacterial inocula for which limited action of cephalexin did not allow to prevent macrophages bursting. The tripartite model we developed is a first step toward innovative in vitro models combining elements of innate immunity with classical bacteria/antibiotics pharmacological models, with the objective of optimising preclinical evaluation of antibacterial drugs

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