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Sayel, Hanane, Nezha Tahri Joutey, Wifak Bahafid y Naima El Ghachtouli. "Chromium Resistant Bacteria: Impact on Plant Growth in Soil Microcosm". Archives of Environmental Protection 40, n.º 2 (8 de julio de 2014): 81–89. http://dx.doi.org/10.2478/aep-2014-0017.
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Abstract Three chromium resistant bacterial strains, Pseudomonas fluorescens PF28, Enterobacter amnigenus EA31 and Enterococcus gallinarum S34 isolated from tannery waste contaminated soil were used in this study. All strains could resist a high concentration of K2Cr2O7 that is up to 300 mg/L. The effect of these strains on clover plants (Trifolium campestre) in the presence of two chromium salts CrCl3 and K2Cr2O7 was studied in soil microcosm. Application of chromium salts adversely affected seed germination, root and shoot length. Bacterial inoculation improved the growth parameters under chromate stress when compared with non inoculated respective controls. There was observed more than 50% reduction of Cr(VI) in inoculated soil microcosms, as compared to the uninoculated soil under the same conditions. The results obtained in this study are significant for the bioremediation of chromate pollution.
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Shintani, Masaki, Tadafumi Horisaki, Hisakazu Yamane, Moriya Ohkuma y Hideaki Nojiri. "Evolution of the IncP-7 carbazole-degradative plasmid pCAR1 improves survival of its host Pseudomonas fluorescens Pf0-1 in artificial water microcosms". Microbiology 157, n.º 8 (1 de agosto de 2011): 2276–86. http://dx.doi.org/10.1099/mic.0.049064-0.
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In our previous study, Pseudomonas fluorescens Pf0-1L, harbouring the IncP-7 carbazole-degradative plasmid pCAR1 : : rfp, was shown to be undetectable within 5 days post-inoculation in carbazole-contaminated artificial freshwater microcosms containing several plasmid-free bacteria in addition to Pf0-1L(pCAR1 : : rfp). Fourteen days after the inoculation, carbazole degraders become detectable. Here, we revealed that these isolates were not pCAR1 transconjugants, but Pf0-1L(pCAR1 : : rfp) mutants, based on RFLP and BOX-A1R-based repetitive extragenic palindromic-PCR (BOX-PCR) analysis. Notably, the mutants displayed more rapid initiation of carbazole degradation than the parent strain Pf0-1L(pCAR1 : : rfp). The mutants were unable to degrade anthranilate due to a 163 bp deletion in the antA gene, which was overcome by their transformation with a wild-type antABC-expressing plasmid. Quantitative RT-PCR analysis indicated that the transcriptional induction of carbazole-, anthranilate- and catechol-degradative genes was comparable in both parent and mutant strains. The deletion mutants became dominant in the artificial water microcosm. The mutation caused anthranilate to accumulate instead of catechol, a toxic compound for the parent strain, and may be beneficial to host survival in artificial microcosms.
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Humphreys, Gavin J. y Andrew J. McBain. "Continuous culture of sessile human oropharyngeal microbiotas". Journal of Medical Microbiology 62, n.º 6 (1 de junio de 2013): 906–16. http://dx.doi.org/10.1099/jmm.0.055806-0.
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The microbiota of the human oropharynx plays an important role in health through involvement in the aetiology of infection and the carriage of adventitious pathogens. Despite this, there are few models available for the preclinical assessment of novel antimicrobials directed to the human throat. We have profiled bacterial consortia sampled from the palatine tonsil and posterior pharyngeal wall microbiotas of healthy adult volunteers (n = 10) using differential culture and 16S rRNA gene sequencing, together with PCR-denaturing gradient gel electrophoresis. The data generated were used to assess the validity of an oropharyngeal microcosm system based on replicated constant-depth film fermenters (CDFFs; n = 5), which were continuously fed using an artificial airway surface liquid. Developed microcosms exhibited significant homology to ex situ consortia according to principal components analysis, whilst compositional reproducibility was apparent in replicated models for tonsillar and pharyngeal inocula. Differential viable count data and Shannon–Weiner diversity indices indicated that representative tonsil and pharyngeal model systems achieved dynamic compositional stability about 6 days after inoculation which could be maintained for ≥20 days. In conclusion, the CDFF facilitated the continuous maintenance of bacteriologically stable microcosms that were compositionally similar to ex situ inocula.
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Carneiro, Marcos Tavares, Daniel Vidal Perez, Renato Castiglia Feitosa y Julio Cesar Wasserman. "Separation of Escherichia coli from natural samples for identification of sources and microcosm inoculation". Brazilian Journal of Microbiology 51, n.º 4 (12 de septiembre de 2020): 2015–20. http://dx.doi.org/10.1007/s42770-020-00374-2.
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Lee, Jiyeon, Sungbo Cho y Hee-Eun Kim. "Antimicrobial Effects of Non-Thermal Atmospheric Pressure Plasma on Oral Microcosm Biofilms". International Journal of Environmental Research and Public Health 20, n.º 3 (30 de enero de 2023): 2447. http://dx.doi.org/10.3390/ijerph20032447.
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We comparatively evaluated the antibacterial effects of non-thermal atmospheric pressure plasma (NTAPP) on oral microcosm biofilms. Oral microcosm biofilms, which are derived from inoculation with human saliva, were cultured on 48 hydroxyapatite disks for 6 days. The prepared biofilms were divided into three different daily treatment groups: distilled water for 1 min, 0.12% chlorhexidine (CHX) for 1 min, and NTAPP for 5 min. Using a quantitative light-induced fluorescence-digital camera, the red fluorescence intensity of the biofilms was measured as red/green ratios (RatioR/G) before and after treatment. Total and aciduric bacteria were counted as colony-forming units. Using live/dead bacterial staining, bacterial viability was calculated as the RatioG/G+R. RatioR/G was approximately 0.91-fold lower in the NTAPP group than in the CHX group on day 1 of treatment (p = 0.001), and approximately 0.94-fold lower on both days 2 and 3 (p < 0.001). The number of total bacteria was higher in the NTAPP group than in the CHX group, but not significantly different. The number of aciduric bacteria was lowest in the CHX group (p < 0.001). However, bacterial viability was lowest in the NTAPP group. Restricted bacterial aggregation was observed in the NTAPP group. These findings suggest that NTAPP may more effectively reduce the pathogenicity of oral microcosm biofilms than 0.12% CHX.
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Sudirman, Sudirman. "EFFECT OF NEMATODE POPULATION DENSITIES ON TRAPPING ACTIVITY OF NEMATOPHAGOUS FUNGUS Arthrobotrys dactyloides ON Meloidogyne javanica". Jurnal Hama dan Penyakit Tumbuhan Tropika 11, n.º 1 (5 de febrero de 2011): 78–86. http://dx.doi.org/10.23960/j.hptt.11178-86.
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Trapping activities of some nematophagous fungi were suggested to be related to the population density of nematodes. This study determined the trapping activity of Arthrobotrys dactyloides due to the effects of (i) different populations of Meloidogyne javanica, (ii) the presence of Caenorhabditis elegans, (iii) repeated inoculation of M. javanica, and (iv) different populations of both C. elegans and M. javanica. Experiments were conducted using a “standard slide test” and “soil microcosm” inoculated with A. dactyloides formulated in kaolin-alginate granules and with low nematode populations ranged from 6 to 14 juveniles per g soil. Results showed that ring formation and trapping activity of A. dactyloides increased with the increase of M. javanica population. The presence of C. elegans increased M. javanica mortality. Repeated inoculation of M. javanica maintained trapping activity of A. dactyloides. The mortality of M. javanica increased with the increase of both C. elegans and M. javanica population.
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Underthun, Kristina, Jaysankar De, Alan Gutierrez, Rachael Silverberg y Keith R. Schneider. "Survival of Salmonella and Escherichia coli in Two Different Soil Types at Various Moisture Levels and Temperatures". Journal of Food Protection 81, n.º 1 (28 de diciembre de 2017): 150–57. http://dx.doi.org/10.4315/0362-028x.jfp-17-226.
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ABSTRACT With the increased consumption of fresh produce, a proportional increase in numbers of produce-related foodborne illness has been observed. An estimate of foodborne illness during 1998 to 2008 attributed ∼46% of the incidences to produce. Any foodborne illness associated with produce can have devastating consequences to the industry. The most recent data from the Centers for Disease Control and Prevention implicate leafy vegetables, vine-stalk vegetables, root vegetables, and sprouts as the most common cause of produce-related foodborne outbreaks. Excess rainfall or flooding, mainly by altering levels of soil moisture and oxygen content, affects the microbial community in soil. The goal of this research was to determine the survivability of a three-serovar Escherichia coli and a five-serovar Salmonella enterica cocktail in microcosms prepared with Candler sand (CS) and Orangeburg sandy loam (OSL) soils. Microcosms were prepared with low, medium, and high volumetric water contents and were incubated at 20 and 30°C. Serotyping was used to determine which E. coli or Salmonella serovar(s) from each cocktail persisted. Microcosm inoculation levels were ∼7.0 log CFU/g. Sampling for CS and OSL microcosms incubated at 20°C ended on day 364 and 357, respectively. The reduction of Salmonella and E. coli to below the limit of detection (extinction) in CS microcosms (incubated at 30°C at all volumetric water content [VWC] levels) was reached on day 168 and 56, respectively. Extinction of Salmonella and E. coli in OSL microcosms (incubated at 30°C at all VWCs) was reached on day 168 and 224, respectively. Of the Salmonella and E. coli serovars analyzed, Salmonella Javiana persisted the longest in both soil types, whereas E. coli O104:H4 and E. coli O145 persisted the longest in CS and OSL microcosms, respectively. Results from the current study suggest that soil type and temperature influenced pathogen persistence in CS and OSL soils more than moisture level and pathogen type.
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Bodor, Attila, Péter Petrovszki, Ágnes Erdeiné Kis, György Erik Vincze, Krisztián Laczi, Naila Bounedjoum, Árpád Szilágyi et al. "Intensification of Ex Situ Bioremediation of Soils Polluted with Used Lubricant Oils: A Comparison of Biostimulation and Bioaugmentation with a Special Focus on the Type and Size of the Inoculum". International Journal of Environmental Research and Public Health 17, n.º 11 (9 de junio de 2020): 4106. http://dx.doi.org/10.3390/ijerph17114106.
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Used lubricant oils (ULOs) strongly bind to soil particles and cause persistent pollution. In this study, soil microcosm experiments were conducted to model the ex situ bioremediation of a long term ULO-polluted area. Biostimulation and various inoculation levels of bioaugmentation were applied to determine the efficacy of total petrol hydrocarbon (TPH) removal. ULO-contaminated soil microcosms were monitored for microbial respiration, colony-forming units (CFUs) and TPH bioconversion. Biostimulation with inorganic nutrients was responsible for 22% of ULO removal after 40 days. Bioaugmentation using two hydrocarbon-degrader strains: Rhodococcus quingshengii KAG C and Rhodococcus erythropolis PR4 at a small inoculum size (107 CFUs g−1 soil), reduced initial TPH concentration by 24% and 29%, respectively; the application of a higher inoculum size (109 CFUs g−1 soil) led to 41% and 32% bioconversion, respectively. After 20 days, all augmented CFUs decreased to the same level as measured in the biostimulated cases, substantiating the challenge for the newly introduced hydrocarbon-degrading strains to cope with environmental stressors. Our results not only highlight that an increased number of degrader cells does not always correlate with enhanced TPH bioconversion, but they also indicate that biostimulation might be an economical solution to promote ULO biodegradation in long term contaminated soils.
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Ingrid, Lenoir, Anissa Lounès-Hadj Sahraoui, Laruelle Frédéric, Dalpé Yolande y Fontaine Joël. "Arbuscular mycorrhizal wheat inoculation promotes alkane and polycyclic aromatic hydrocarbon biodegradation: Microcosm experiment on aged-contaminated soil". Environmental Pollution 213 (junio de 2016): 549–60. http://dx.doi.org/10.1016/j.envpol.2016.02.056.
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Edge, Thomas A. y R. Campbell Wyndham. "Predicting survival of a genetically engineered microorganism,Pseudomonas chlororaphis3732RN-L11, in soil and wheat rhizosphere across Canada with linear multiple regression models". Canadian Journal of Microbiology 48, n.º 8 (1 de agosto de 2002): 717–27. http://dx.doi.org/10.1139/w02-066.
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Pseudomonas chlororaphis 3732RN-L11 survival rates in soil and wheat rhizosphere were measured using intact soil core microcosms representing 23 sites across Canada. Linear multiple regression (LMR) models were developed to predict the survival rate of this genetically engineered microorganism (GEM) as a function of soil parameters measured at the time of microcosm inoculation. LMR models were tested by comparing their predicted survival rates with observed survival rates from environmental introductions of the GEM by Gagliardi et al. (2001) at five field sites across Canada over two years. No soil parameter (e.g., % clay) was highly correlated with GEM survival rates in soil or wheat rhizosphere. Total fungal colony-forming units (CFUs), % soil titanium (positive correlations), and % soil magnesium (negative correlation) were found to be the best LMR predictors of GEM survival rates in soil over two years. Total soil bacterial CFUs, nitrate, % soil potassium (positive correlations), and exchangeable magnesium (negative correlation) were found to be the best LMR predictors of GEM survival rate in wheat rhizosphere over two years. While LMR models were statistically significant, they were unable to reliably predict the survival rate of the GEM in field trial introductions. The results indicate that there can be considerable uncertainty associated with predicting GEM survival for multi-site environmental introductions.Key words: Pseudomonas chlororaphis 3732RN-L11, survival, soil, Canada.
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Hynes, S. S., O. Chaudhry, M. A. Providenti y M. L. Smith. "Development of AFLP-derived, functionally specific markers for environmental persistence studies of fungal strains". Canadian Journal of Microbiology 52, n.º 5 (1 de mayo de 2006): 451–61. http://dx.doi.org/10.1139/w05-140.
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The ability to rapidly identify and quantify a microbial strain in a complex environmental sample has widespread applications in ecology, epidemiology, and industry. In this study, we describe a rapid method to obtain functionally specific genetic markers that can be used in conjunction with standard or real-time polymerase chain reaction (PCR) to determine the abundance of target fungal strains in selected environmental samples. The method involves sequencing of randomly cloned AFLP (amplified fragment length polymorphism) products from the target organism and the design of PCR primers internal to the AFLP fragments. The strain-specific markers were used to determine the fate of three industrially relevant fungi, Aspergillus niger, Aspergillus oryzae, and Chaetomium globosum, during a 4 month soil microcosm experiment. The persistence of each of the three fungal strains inoculated separately into intact soil microcosms was determined by PCR analyses of DNA directly extracted from soil. Presence and absence data based on standard PCR and quantification of the target DNA by real-time PCR showed that all three strains declined after inoculation (~14-, 32-, and 4-fold for A. niger, A. oryzae, and C. globosum, respectively) but remained detectable at the end of the experiment, suggesting that these strains would survive for extended periods if released into nature.Key words: Canada domestic substances list (DSL), Canadian Environmental Protection Act (CEPA), genetically modified organisms (GMO), quantitative polymerase chain reaction (qPCR).
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TOPALCENGIZ, ZEYNAL, RACHEL McEGAN y MICHELLE D. DANYLUK. "Fate of Salmonella in Central Florida Surface Waters and Evaluation of EPA Worst Case Water as a Standard Medium". Journal of Food Protection 82, n.º 6 (13 de mayo de 2019): 916–25. http://dx.doi.org/10.4315/0362-028x.jfp-18-331.
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ABSTRACT Salmonella persistence in sterile surface water, nonsterile surface water, or deionized water over 336 days was explored. The suitability of EPA (U.S. Environmental Protection Agency) Worst Case water as a standard medium was also evaluated. Salmonella was enumerated by spread plating or most probable number at set time points after inoculation into water (sterile and nonsterile surface, deionized, and EPA Worst Case waters) and held at 15, 21, or 28°C. Total coliforms from nonsterile waters were enumerated by spread plating. Salmonella decreased most rapidly in nonsterile surface water. Addition of cycloheximide to nonsterile surface waters did not increase Salmonella survival compared with the same nonsterile surface water without cycloheximide except for the water held at 15°C. Total coliform populations decreased to below the limit of detection at 112 days; Salmonella remained detectable throughout the entire 168-day experiment. Salmonella populations persist at least 336 days in all waters tested; coliforms remained detectable to 112 days. Rates of decline (time required for a 1-log reduction) in nonsterile waters were at least five times shorter than those of other water types. EPA Worst Case water is a suitable standard for surface water microcosms. This study adds to the limited knowledge regarding Salmonella survival in surface waters. It demonstrates the potential long-term survival of Salmonella in fresh water and the importance of biotic factors when designing microcosm-based experiments. HIGHLIGHTS
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Bae, Sungwoo y Stefan Wuertz. "Survival of Host-Associated Bacteroidales Cells and Their Relationship with Enterococcus spp., Campylobacter jejuni, Salmonella enterica Serovar Typhimurium, and Adenovirus in Freshwater Microcosms as Measured by Propidium Monoazide-Quantitative PCR". Applied and Environmental Microbiology 78, n.º 4 (2 de diciembre de 2011): 922–32. http://dx.doi.org/10.1128/aem.05157-11.
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ABSTRACTThe ideal host-associated genetic fecal marker would be capable of predicting the presence of specific pathogens of concern. Flowthrough freshwater microcosms containing mixed feces and inocula of the pathogensCampylobacter jejuni,Salmonella entericaserovar Typhimurium, and adenovirus were placed at ambient temperature in the presence and absence of diurnal sunlight. The totalEnterococcusDNA increased during the early periods (23 h) under sunlight exposure, even though cultivableEnterococcusand DNA in intact cells, as measured by propidium monoazide (PMA), decreased with first-order kinetics during the entire period. We found a significant difference in the decay of host-associatedBacteroidalescells between sunlight exposure and dark conditions (Pvalue < 0.05), whereas the persistence of host-associatedBacteroidalesDNA was comparable. The 2-log reduction times of adenovirus were 72 h for sunlight exposure and 99 h for dark conditions with similar decay rate constants (Pvalue = 0.13). The persistences of fecalBacteroidalescells andCampylobactercells exposed to sunlight were similar, and host-associatedBacteroidalesDNA and waterborne pathogen DNA were degraded at comparable rates (Pvalues > 0.05). Overall, the ratio of quantitative PCR (qPCR) cycle threshold (CT) values with and without PMA treatment was indicative of the time elapsed since inoculation of the microcosm with (i) fecal material from different animal sources based on host-associatedBacteroidalesand (ii) pure cultures of bacterial pathogens. The use of both PMA-qPCR and qPCR may yield more realistic information about recent sources of fecal contamination and result in improved prediction of waterborne pathogens and assessment of health risk.
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Sefbom, Josefin, Ingrid Sassenhagen, Karin Rengefors y Anna Godhe. "Priority effects in a planktonic bloom-forming marine diatom". Biology Letters 11, n.º 5 (mayo de 2015): 20150184. http://dx.doi.org/10.1098/rsbl.2015.0184.
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Priority effects occur when a species or genotype with earlier arrival has an advantage such that its relative abundance in the community or population is increased compared with later-arriving species. Few studies have dealt with this concept in the context of within-species competition. Skeletonema marinoi is a marine diatom that shows a high degree of genetic differentiation between populations over small geographical distances. To test whether historical events such as priority effects may have been important in inducing these patterns of population differentiation, we performed microcosm experiments with successive inoculation of different S. marinoi strains. Our results show that even in the absence of a numerical advantage, significant priority effects were evident. We propose that priority effects may be an important mechanism in initiating population genetic differentiation.
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Bencherif, Karima, Frédéric Laruelle, Yolande Dalpé y Anissa Lounès-Hadj Sahraoui. "Inoculum Sources Modulate Mycorrhizal Inoculation Effect on Tamarix articulata Development and Its Associated Rhizosphere Microbiota". Plants 10, n.º 12 (10 de diciembre de 2021): 2716. http://dx.doi.org/10.3390/plants10122716.
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(1) Background: Soil degradation is an increasingly important problem in many parts of the world, particularly in arid and semiarid areas. Arbuscular mycorrhizal fungi (AMF) isolated from arid soils are recognized to be better adapted to these edaphoclimatic conditions than exogenous ones. Nevertheless, little is known about the importance of AMF inoculum sources on Tamarix articulata development in natural saline soils. Therefore, the current study aims at investigating the efficiency of two AMF-mixed inoculums on T. articulata growth, with consideration of its rhizosphere microbiota. (2) Methods: indigenous inoculum made of strains originating from saline soils and a commercial one were used to inoculate T. articulata in four saline soils with different salinity levels under microcosm conditions with evaluation of rhizosphere microbial biomasses. (3) Results: Our findings showed that indigenous inoculum outperforms the commercial one by 80% for the mycorrhizal rate and 40% for plant biomasses, which are correlated with increasing shoot phosphorus content. Soil microbial biomasses increased significantly with indigenous mycorrhizal inoculum in the most saline soil with 46% for AMF, 25% for saprotrophic fungi and 15% for bacterial biomasses. (4) Conclusion: Present results open the way towards the preferential use of mycorrhizal inoculum, based on native AMF, to perform revegetation and to restore the saline soil microbiota.
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LEE, DEBBIE, MOUKARAM TERTULIANO, CASEY HARRIS, GEORGE VELLIDIS, KAREN LEVY y TIMOTHY COOLONG. "Salmonella Survival in Soil and Transfer Onto Produce via Splash Events". Journal of Food Protection 82, n.º 12 (6 de noviembre de 2019): 2023–37. http://dx.doi.org/10.4315/0362-028x.jfp-19-066.
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ABSTRACT Nearly one-half of foodborne illnesses in the United States can be attributed to fresh produce consumption. The preharvest stage of production presents a critical opportunity to prevent produce contamination in the field from contaminating postharvest operations and exposing consumers to foodborne pathogens. One produce-contamination route that is not often explored is the transfer of pathogens in the soil to edible portions of crops via splash water. We report here on the results from multiple field and microcosm experiments examining the potential for Salmonella contamination of produce crops via splash water, and the effect of soil moisture content on Salmonella survival in soil and concentration in splash water. In field and microcosm experiments, we detected Salmonella for up to 8 to 10 days after inoculation in soil and on produce. Salmonella and suspended solids were detected in splash water at heights of up to 80 cm from the soil surface. Soil-moisture conditions before the splash event influenced the detection of Salmonella on crops after the splash events—Salmonella concentrations on produce after rainfall were significantly higher in wet plots than in dry plots (geometric mean difference = 0.43 CFU/g; P = 0.03). Similarly, concentrations of Salmonella in splash water in wet plots trended higher than concentrations from dry plots (geometric mean difference = 0.67 CFU/100 mL; P = 0.04). These results indicate that splash transfer of Salmonella from soil onto crops can occur and that antecedent soil-moisture content may mediate the efficiency of microbial transfer. Splash transfer of Salmonella may, therefore, pose a hazard to produce safety. The potential for the risk of splash should be further explored in agricultural regions in which Salmonella and other pathogens are present in soil. These results will help inform the assessment of produce safety risk and the development of management practices for the mitigation of produce contamination. HIGHLIGHTS
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Araújo, Daniela Bastos, Suzana Cláudia Silveira Martins, Laurênia Maria Braga de Albuquerque y Ernesto Hofer. "Influence of the copepod Mesocyclops longisetus (Crustacea: Cyclopidae) on the survival of Vibrio cholerae O1 in fresh water". Cadernos de Saúde Pública 12, n.º 4 (diciembre de 1996): 551–54. http://dx.doi.org/10.1590/s0102-311x1996000400015.
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In an experimental microcosm, an analysis was performed of the influence exerted by freshwater Mesocyclops longisetus copepods on the survival of Vibrio cholerae O1 serovar Inaba. In the State of Ceará, copepods are used in the control of Aedes aegypti larvae. The system consisted of water with a salinity of 0.27‰ and pH 7.5, which after sterilizing filtration was distributed into seven flasks with a volume of 400 ml; in each of six flasks, 10 live copepods were inoculated along with 1 ml of an 8-hour culture of Vibrio cholerae O1 at 37ºC in Alkaline Peptone Water, resulting in a concentration of 3.80x10(4) colony-forming units. The control flask contained only the water with the same bacterial suspension. The system was maintained for six days at room temperature (25-28ºC), and daily duplicate counts were performed in TCBS Agar. Results confirmed a clear association between Vibrio cholerae O1 and the live copepods, based on survival of the bacteria at compatible levels with the initial inoculation until the sixth day of the analysis.
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Szczech, Magdalena y Makoto Shoda. "The influence ofBacillus subtilisRB14-C on the development ofRhizoctonia solaniand indigenous microorganisms in the soil". Canadian Journal of Microbiology 51, n.º 5 (1 de mayo de 2005): 405–11. http://dx.doi.org/10.1139/w05-018.
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The effect of soil inoculation with an antagonistic strain Bacillus subtilis RB14-C on the development of Rhizoctonia solani and changes occurring in soil and rhizosphere microbial communities were studied. RB14-C was added to the soil as a water suspension of the cells or as a broth culture. Application of cell suspensions to non-planted soil reduced the number of culturable bacteria. The density of R. solani and the number of filamentous fungi were not significantly affected by RB14-C. A similar effect was observed in the rhizosphere of tomato plants growns in bacterized soil. Broth cultures of RB14-C suppressed R. solani 1 d after inoculation, but after 3 d there was no difference in the pathogen density between soil amended with broth culture and control soil. In microcosm studies, cell suspensions of RB14-C also did not inhibit growth of R. solani on filters buried in soil. However, an inhibitory effect was obtained when a broth culture of the bacterium was used. The effect of RB14-C on fungal biomass was also estimated by measurement of ergosterol concentration in soil. It was found that ergosterol was mostly derived from R. solani and that there were no significant differences in its content between untreated soil and soil treated with RB14-C. The results suggest that suppression of Rhizoctonia damping-off by B. subtilis RB14-C probably is not related to the reduction of the pathogen population in the soil.Key words: B. subtilis, R. solani, ergosterol, native microflora.
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Bi, Yinli, Li Xiao y Rongrong Liu. "Response of arbuscular mycorrhizal fungi and phosphorus solubilizing bacteria to remediation abandoned solid waste of coal mine". International Journal of Coal Science & Technology 6, n.º 4 (10 de septiembre de 2019): 603–10. http://dx.doi.org/10.1007/s40789-019-00270-7.
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Abstract Coal is the vital resource of energy in China, but abandoned coal ash and gangue lead to the degradation of vegetation cover and reduce soil quality. Both arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) play a key role in biogeochemical cycle such as soil organic matter decomposition, nutrition release, and energy flow. To improve and reclamation the soil quality and ecological efficiency of the coal mining waste, we investigated the effects of an AMF strain (Glomus mosseae) and a PSB strain (Pantoesstewarti) on phytate mineralization and subsequent transfer to the host plant (Medicago sativa L.) using a two-compartment microcosm with a central 30 mm nylon mesh barrier. The results showed that significantly higher available P (AP), above ground biomass (AGB) and underground biomass (UGB) were in combined inoculation of AMF-PSB than other treatments in root and hyphae compartment. The microbial inoculum of the AMF or PSB had a significant influence on soil acid phosphatase activities (ACP). AMF-PSB enhanced phytate mineralization, improved plant biomass. AP and ACP positively influenced the AGB and UGB. AMF-PSB could be used as bioinoculant to enhance sustainable production of the plant in abandoned solid waste of coal mine.
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Jung, Seung Won, Seong Yu Noh, Donhyug Kang y Taek-Kyun Lee. "Comparison of bacterioplankton communities between before and after inoculation with an algicidal material, Ca-aminoclay, to mitigate Cochlodinium polykrikoides blooms: assessment using microcosm experiments". Journal of Applied Phycology 29, n.º 3 (31 de enero de 2017): 1343–54. http://dx.doi.org/10.1007/s10811-017-1068-8.
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Kim, Youngjun, Sangeun Park y Seungdae Oh. "Machine Learning Approach Reveals the Assembly of Activated Sludge Microbiome with Different Carbon Sources during Microcosm Startup". Microorganisms 9, n.º 7 (25 de junio de 2021): 1387. http://dx.doi.org/10.3390/microorganisms9071387.
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Activated sludge (AS) microcosm experiments usually begin with inoculating a bioreactor with an AS mixed culture. During the bioreactor startup, AS communities undergo, to some extent, a distortion in their characteristics (e.g., loss of diversity). This work aimed to provide a predictive understanding of the dynamic changes in the community structure and diversity occurring during aerobic AS microcosm startups. AS microcosms were developed using three frequently used carbon sources: acetate (A), glucose (G), and starch (S), respectively. A mathematical modeling approach quantitatively determined that 1.7–2.4 times the solid retention time (SRT) was minimally required for the microcosm startups, during which substantial divergences in the community biomass and diversity (33–45% reduction in species richness and diversity) were observed. A machine learning modeling application using AS microbiome data could successfully (>95% accuracy) predict the assembly pattern of aerobic AS microcosm communities responsive to each carbon source. A feature importance analysis pinpointed specific taxa that were highly indicative of a microcosm feed source (A, G, or S) and significantly contributed for the ML-based predictive classification. The results of this study have important implications on the interpretation and validity of microcosm experiments using AS.
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Schreiner, Karin, Alexandra Hagn, Martina Kyselková, Yvan Moënne-Loccoz, Gerhard Welzl, Jean Charles Munch y Michael Schloter. "Comparison of Barley Succession and Take-All Disease as Environmental Factors Shaping the Rhizobacterial Community during Take-All Decline". Applied and Environmental Microbiology 76, n.º 14 (4 de junio de 2010): 4703–12. http://dx.doi.org/10.1128/aem.00481-10.
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ABSTRACT The root disease take-all, caused by Gaeumannomyces graminis var. tritici, can be managed by monoculture-induced take-all decline (TAD). This natural biocontrol mechanism typically occurs after a take-all outbreak and is believed to arise from an enrichment of antagonistic populations in the rhizosphere. However, it is not known whether these changes are induced by the monoculture or by ecological rhizosphere conditions due to a disease outbreak and subsequent attenuation. This question was addressed by comparing the rhizosphere microflora of barley, either inoculated with the pathogen or noninoculated, in a microcosm experiment in five consecutive vegetation cycles. TAD occurred in soil inoculated with the pathogen but not in noninoculated soil. Bacterial community analysis using terminal restriction fragment length polymorphism of 16S rRNA showed pronounced population shifts in the successive vegetation cycles, but pathogen inoculation had little effect. To elucidate rhizobacterial dynamics during TAD development, a 16S rRNA-based taxonomic microarray was used. Actinobacteria were the prevailing indicators in the first vegetation cycle, whereas the third cycle—affected most severely by take-all—was characterized by Proteobacteria, Bacteroidetes, Chloroflexi, Planctomycetes, and Acidobacteria. Indicator taxa for the last cycle (TAD) belonged exclusively to Proteobacteria, including several genera with known biocontrol traits. Our results suggest that TAD involves monoculture-induced enrichment of plant-beneficial taxa.
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Caravaca, F., A. Pera, G. Masciandaro, B. Ceccanti y A. Roldán. "A microcosm approach to assessing the effects of earthworm inoculation and oat cover cropping on CO2 fluxes and biological properties in an amended semiarid soil". Chemosphere 59, n.º 11 (junio de 2005): 1625–31. http://dx.doi.org/10.1016/j.chemosphere.2004.12.032.
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Martínez-Hidalgo, Pilar, José David Flores-Félix, Fernando Sánchez-Juanes, Raúl Rivas, Pedro F. Mateos, Ignacio Santa Regina, Álvaro Peix, Eustoquio Martínez-Molina, José M. Igual y Encarna Velázquez. "Identification of Canola Roots Endophytic Bacteria and Analysis of Their Potential as Biofertilizers for Canola Crops with Special Emphasis on Sporulating Bacteria". Agronomy 11, n.º 9 (8 de septiembre de 2021): 1796. http://dx.doi.org/10.3390/agronomy11091796.
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Canola (Brassica napus L. var. oleracea) is the third most common oil-producing crop worldwide after palm and soybean. Canola cultivation requires the use of chemical fertilizers, but the amount required can be reduced by applying plant growth-promoting bacteria (PGPB). Among PGPB, endophytic bacteria have certain advantages as biofertilizers, but canola endophytic bacteria have rarely been studied. In this work, we identified a collection of bacterial endophytes isolated from canola roots using MALDI-TOF MS, a technique that is still rarely used for the identification of such bacteria, and rrs gene sequencing, a methodology that is commonly used to identify canola endophytes. The results demonstrated that some bacterial isolates from canola roots belonged to the genera Bacillus, Neobacillus, Peribacillus (Pe.), and Terribacillus, but most isolates belonged to the genera Paenibacillus (P.) and Pseudomonas (Ps.). Inoculation of these isolates indicated that several of them could efficiently promote canola seedling growth in hydroponic conditions. These results were then confirmed in a microcosm experiment using agricultural soil, which demonstrated that several isolates of Pseudomonas thivervalensis, Paenibacillus amylolyticus, Paenibacillus polymyxa, Paenibacillus sp. (Paenibacillus glucanolyticus/Paenibacillus lautus group), and Peribacillus simplex (previously Bacillus simplex) could efficiently promote canola shoot growth under greenhouse conditions. Among them, the isolates of Paenibacillus and Peribacillus were the most promising biofertilizers for canola crops as they are sporulated rods, which is an advantageous trait when formulating biofertilizers.
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Nikolopoulou, Ioanna, Odysseas Piperagkas, Stefanos Moschos y Hera Karayanni. "Bacteria Release from Microplastics into New Aquatic Environments". Diversity 15, n.º 1 (13 de enero de 2023): 115. http://dx.doi.org/10.3390/d15010115.
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Microplastics are considered the most common waste in aquatic ecosystems, and studying them along with their interactions with biota are considered a priority. Here, results on the role of microplastics in the dispersion of microbes from terrestrial to aquatic ecosystems are presented. Data were obtained from microcosm experiments in which microplastics (plastic bags (BA), polyethylene bottles (BO), acrylic beads (BE), and cigarette butts (BU)) with their attached natural bacterial communities were inoculated in filtered and autoclaved lake water. The bacterial abundance on microplastics was estimated before inoculation using a protocol for the enumeration of sediment bacteria and ranged between 1.63 (BA) and 203.92 (BE) × 103 cells mm−2. Bacteria were released in the new medium, and their growth rates reached 5.8 d−1. In the attached communities, Beta- (21.4%) and Alphaproteobacteria (18.6%) were the most abundant classes, while in the free-living communities Gammaproteobacteria dominated (48.07%). Abundant OTUs (≥1%) of the free-living communities were associated with the genera Acinetobacter, Pseudomonas, Ecidovorax, Delftia, Comamonas, Sphingopyxis, and Brevundimonas and members of the FCB group. Members of these genera are known to degrade natural or man-made organic compounds and have recently emerged as opportunistic pathogens. Thus, besides trophic transmission, microplastics can directly release bacteria in the environment, which could affect the health of humans, animals, and ecosystems.
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Wakelin, S. A., V. V. S. R. Gupta, P. R. Harvey y M. H. Ryder. "The effect of Penicillium fungi on plant growth and phosphorus mobilization in neutral to alkaline soils from southern Australia". Canadian Journal of Microbiology 53, n.º 1 (1 de enero de 2007): 106–15. http://dx.doi.org/10.1139/w06-109.
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The phosphate solubilizing fungi Penicillium radicum, Penicillium bilaiae (strain RS7B-SD1), and an unidentified Penicillium sp. designated strain KC6-W2 were tested for their ability to increase the growth and phosphorus (P) nutrition of wheat, medic, and lentil in three soils of neutral to alkaline pH reaction. The strongest plant growth promoting (PGP) strain was Penicillium sp. KC6-W2, which stimulated significant increases in shoot growth and dry mass in seven of the nine experiments conducted. Levels of PGP by Penicillium sp. KC6-W2 ranged from 6.6% to 19% and were associated with increased uptake of P to the shoot. The PGP properties of Penicillium sp. KC6-W2 were evident on each of the three different plant species and soil types, a level of reliability not observed in other strains tested. Inoculation of seed with P. radicum increased lentil growth by 5.5% (P < 0.05) in soil from Tarlee but did not affect plant growth in the eight other experiments. Inoculation of plant seed with P. bilaiae RS7B-SD1 resulted in significant PGP in two of the nine experiments conducted. However, when significant, stimulation of PGP by P. bilaiae RS7B-SD1 was strong and resulted in increases in medic dry matter (19%) and lentil shoot dry matter (15%). A soil microcosm experiment investigated the effect of Penicillium fungi on cycling of soil P. Penicillium bilaiae RS7B-SD1 was the only fungus to significantly increase HCO3-extractable P (23% increase; P < 0.05). Production of phosphatase enzymes was not associated with increased HCO3-extractable P. Addition of carbon in the form of ryegrass seed significantly increased microbial respiration and movement of P to the microbial biomass (P < 0.05), but these parameters were irrespective of Penicillium treatment. This work has established the potential for use of Penicillium inoculants to increase plant growth on alkaline soils in Australia. The role of Penicillium fungi in plant P uptake and soil P cycling requires further exploration.Key words: Penicillium, phosphorus, plant growth promotion, phosphatase, rhizobia.
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Warmink, J. A. y J. D. van Elsas. "Migratory Response of Soil Bacteria to Lyophyllum sp. Strain Karsten in Soil Microcosms". Applied and Environmental Microbiology 75, n.º 9 (13 de marzo de 2009): 2820–30. http://dx.doi.org/10.1128/aem.02110-08.
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ABSTRACT In this study, the selection of bacteria on the basis of their migration via fungal hyphae in soil was investigated in microcosm experiments containing Lyophyllum sp. strain Karsten (DSM2979). One week following inoculation with a bacterial community obtained from soil, selection of a few specific bacterial types was noticed at 30 mm in the growth direction of Lyophyllum sp. strain Karsten in sterile soil. Cultivation-based analyses showed that the migration-proficient types encompassed 10 bacterial groups, as evidenced by (GTG)5 genomic fingerprinting as well as 16S rRNA gene sequencing. These were (>97% similarity) Burkholderia terrae BS001, Burkholderia sordidicola BS026, Burkholderia sediminicola BS010, and Burkholderia phenazinium BS028; Dyella japonica BS013, BS018, and BS021; “Sphingoterrabacterium pocheensis” BS024; Sphingobacterium daejeonense BS025; and Ralstonia basilensis BS017. Migration as single species was subsequently found for B. terrae BS001, D. japonica BS018 and BS021, and R. basilensis BS017. Typically, migration occurred only when these organisms were introduced at the fungal growth front and only in the direction of hyphal growth. Migration proficiency showed a one-sided correlation with the presence of the hrcR gene, used as a marker for the type III secretion system (TTSS), as all single-strain migrators were equipped with this system and most non-single-strain migrators were not. The presence of the TTSS stood in contrast to the low prevalence of TTSSs within the bacterial community used as an inoculum (<3%). Microscopic examination of B. terrae BS001 in contact with Lyophyllum sp. strain Karsten hyphae revealed the development of a biofilm surrounding the hyphae. Migration-proficient bacteria interacting with Lyophyllum sp. strain Karsten may show complex behavior (biofilm formation) at the fungal tip, leading to their translocation and growth in novel microhabitats in soil.
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Vergnano, Andrea, Carla Maria Raffa, Alberto Godio y Fulvia Chiampo. "Electromagnetic Properties Monitoring to Detect Different Biodegradation Kinetics in Hydrocarbon-Contaminated Soil". Soil Systems 6, n.º 2 (24 de mayo de 2022): 48. http://dx.doi.org/10.3390/soilsystems6020048.
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The electromagnetic properties (electrical permittivity and electrical conductivity) of three different soil mesocosms polluted with diesel oil were monitored using a time-domain reflectometry probe for 8 months. The main target of the research was to establish a relationship between the development of biological activity within the mesocosms and the temporal behaviour of electromagnetic properties. The trend of the electromagnetic properties exhibited different responses that could be related to the composition of the mesocosms and their variation with time during the runs. We considered three different mesocosms with similar soil conditions and the same diesel oil concentration: porosity of 45%, volumetric diesel oil content of 9%, and volumetric water content of 15%. The first one was subjected to a natural attenuation (NA), the second one was biostimulated without inoculation (BS), and the third one was biostimulated with inoculation (BS + IN). The biostimulated mesocosms showed a marked decrease in electrical permittivity and electrical conductivity, whereas the naturally attenuated mesocosm did not show these variations. Between the biostimulated mesocosms, the inoculated one showed the fastest variations in the electromagnetic properties. The microbial activity and the pollutant degradation were evidenced by the analyses performed at the end of the experiment. As demonstrated by the results for the fluorescein diacetate analysis, the microbial activity was a bit higher for the inoculated microcosm, which also showed faster variations of the electromagnetic properties. In the biostimulated mesocosms, the removal of diesel oil was 66% and 72%, respectively. With natural attenuation, there was a limited removal efficiency, in the order of 2%. Even if the electromagnetic properties evidenced different kinetics of bioremediation in BS and BS + IN, both were able to successfully degrade similar percentages of the contaminant after 8 months. The long monitoring revealed that a substantial decrease in the electromagnetic properties happened only in the first month after contamination. Additionally, an increasing trend of the permittivity was detected in the following months, before reaching a steady-state condition. This study revealed that biodegradation processes with acceptable overall removal efficiency can be monitored successfully by observing the variations in the electromagnetic properties.
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Franklin, Rima B., Jay L. Garland, Carl H. Bolster y Aaron L. Mills. "Impact of Dilution on Microbial Community Structure and Functional Potential: Comparison of Numerical Simulations and Batch Culture Experiments". Applied and Environmental Microbiology 67, n.º 2 (1 de febrero de 2001): 702–12. http://dx.doi.org/10.1128/aem.67.2.702-712.2001.
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ABSTRACT A series of microcosm experiments was performed using serial dilutions of a sewage microbial community to inoculate a set of batch cultures in sterile sewage. After inoculation, the dilution-defined communities were allowed to regrow for several days and a number of community attributes were measured in the regrown assemblages. Based upon a set of numerical simulations, community structure was expected to differ along the dilution gradient; the greatest differences in structure were anticipated between the undiluted–low-dilution communities and the communities regrown from the very dilute (more than 10−4) inocula. Furthermore, some differences were expected among the lower-dilution treatments (e.g., between undiluted and 10−1) depending upon the evenness of the original community. In general, each of the procedures used to examine the experimental community structures separated the communities into at least two, often three, distinct groups. The groupings were consistent with the simulated dilution of a mixture of organisms with a very uneven distribution. Significant differences in community structure were detected with genetic (amplified fragment length polymorphism and terminal restriction fragment length polymorphism), physiological (community level physiological profiling), and culture-based (colony morphology on R2A agar) measurements. Along with differences in community structure, differences in community size (acridine orange direct counting), composition (ratio of sewage medium counts to R2A counts, monitoring of each colony morphology across the treatments), and metabolic redundancy (i.e., generalist versus specialist) were also observed, suggesting that the differences in structure and diversity of communities maintained in the same environment can be manifested as differences in community organization and function.
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Craig, D. L., H. J. Fallowfield y N. J. Cromar. "Comparison of decay rates of faecal indicator organisms in recreational coastal water and sediment". Water Supply 2, n.º 3 (1 de julio de 2002): 131–38. http://dx.doi.org/10.2166/ws.2002.0095.
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A laboratory based microcosm study utilising intact non-sterile sediment cores was undertaken to determine the survival of the faecal indicator organisms Escherichia coli, Enterococcus faecium and somatic coliphage in both recreational coastal water and sediment. Overlying water was inoculated with the test organisms and incubated at 10°C, 20°C or 30°C. E. coli, enterococcus and coliphage were enumerated from the water column and sediment by the membrane filtration method, Enterolert (IDEXX Laboratories) and the double-agar overlay methods respectively on days 0, 1, 2, 7, 14 and 28 following inoculation. It was demonstrated that for all organisms, greater decay (k; d-1) occurred in the water column compared to sediment. Sediment characteristics were found to influence decay, with lowest decay rates observed in sediment consisting of high organic carbon content and small particle size. Decay of E. coli was significantly greater in both the water column and sediment compared with enterococcus and coliphage under all conditions. Decay of enterococcus was found to closely resemble that of coliphage decay. Survival of all organisms was inversely related to temperature, with greatest decay at 30°C. However, increased temperature had a less significant impact on survival of enterococcus and coliphage compared with E. coli. The importance of this study for estimating risk from recreational exposure is great if some pathogenic microorganisms behave similarly to the organisms tested in this study. In particular if survival rates of pathogens are similar to enterococcus and coliphage, then their ability to accumulate in coastal sediment may lead to an increased risk of exposure if these organisms are resuspended into the water column due to natural turbulence or human recreational activity.
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Ramesh, Aketi, Sushil K. Sharma, Namrata Yadav y O. P. Joshi. "Phosphorus Mobilization from Native Soil P-Pool upon Inoculation with Phytate-Mineralizing and Phosphate-Solubilizing Bacillus aryabhattai Isolates for Improved P-Acquisition and Growth of Soybean and Wheat Crops in Microcosm Conditions". Agricultural Research 3, n.º 2 (15 de mayo de 2014): 118–27. http://dx.doi.org/10.1007/s40003-014-0105-y.
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Kuiper, Irene, Lev V. Kravchenko, Guido V. Bloemberg y Ben J. J. Lugtenberg. "Pseudomonas putida Strain PCL1444, Selected for Efficient Root Colonization and Naphthalene Degradation, Effectively Utilizes Root Exudate Components". Molecular Plant-Microbe Interactions® 15, n.º 7 (julio de 2002): 734–41. http://dx.doi.org/10.1094/mpmi.2002.15.7.734.
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Previously, we have described the selection of a plant-bacterium pair that is efficient in rhizoremediating naphthalene pollution in microcosm studies. After repeated selection for efficient root tip colonization upon inoculation of seeds of grass cv. Barmultra and for stable and efficient growth on naphthalene, Pseudomonas putida PCL1444 was selected as the most efficient colonizer of Barmultra roots. Here, we report the analysis of Barmultra root exudate composition and our subsequent tests of the growth rate of the bacterium and of the expression of the naphthalene degradation genes on individual exudate components. High performance liquid chromatography analysis of the organic acid and sugar root-exudate components revealed that glucose and fructose are the most abundant sugars, whereas succinic acid and citric acid are the most abundant organic acids. Tn5luxAB mutants of PCL1444 impaired in naphthalene degradation appeared to be impaired in genes homologous to genes of the upper naphthalene degradation pathway present in various Pseudomonas strains and to genes of the lower pathway genes for naphthalene degradation in P. stutzeri. Highest expression for both pathways involved in naphthalene degradation during growth in minimal medium with the carbon source to be tested was observed at the start of the logarithmic phase. Naphthalene did not induce the upper pathway, but a different pattern of expression was observed in the lower pathway reporter, probably due to the conversion of naphthalene to salicylic acid. Salicylic acid, which is described as an intermediate of the naphthalene degradation pathway in many Pseudomonas strains, did induce both pathways, resulting in an up to sixfold higher expression level at the start of the logarithmic phase. When expression levels during growth on the different carbon sources present in root exudate were compared, highest expression was observed on the two major root exudate components, glucose and succinic acid. These results show an excellent correlation between successful naphthalene rhizoremediation by the Barmultra-P. putida PCL1444 pair and both efficient utilization of the major exudate components for growth and high transcription of the naphthalene catabolic genes on the major exudate components. Therefore, we hypothesize that efficient root colonizing and naphthalene degradation is the result of the applied colonization enrichment procedure.
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Mertens, Birgit, Nico Boon y Willy Verstraete. "Slow-Release Inoculation Allows Sustained Biodegradation of γ-Hexachlorocyclohexane". Applied and Environmental Microbiology 72, n.º 1 (enero de 2006): 622–27. http://dx.doi.org/10.1128/aem.72.1.622-627.2006.
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ABSTRACT This study investigated the feasibility of a slow-release inoculation approach as a bioaugmentation strategy for the degradation of lindane (γ-hexachlorocyclohexane [γ-HCH]). Slow-release inoculation of Sphingomonas sp. γ 1-7 was established in both liquid and soil slurry microcosms using open-ended silicone tubes in which the bacteria are encapsulated in a protective nutrient-rich matrix. The capacity of the encapsulated cells to degrade lindane under aerobic conditions was evaluated in comparison with inoculation of free-living cells. Encapsulation of cells in tubes caused the removal of lindane by adsorption to the silicone tubes but also ensured prolonged biodegradation activity. Lindane degradation persisted 2.2 and 1.4 times longer for liquid and soil slurry microcosms, respectively, than that for inoculation with free cells. While inoculation of free-living cells led to a loss in lindane-degrading activity in limited time intervals, encapsulation in tubes allowed for a more stable actively degrading community. The loss in degrading activity was linked to the loss of the linA gene, encoding γ-HCH dehydrochlorinase (LinA), which is involved in the initial steps of the lindane degradation pathway. This work shows that a slow-release inoculation approach using a catabolic strain encapsulated in open-ended tubes is a promising bioaugmentation tool for contaminated sites, as it can enhance pollutant removal and can prolong the degrading activity in comparison with traditional inoculation strategies.
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Gupte, A. R., C. L. E. de Rezende y S. W. Joseph. "Induction and Resuscitation of Viable but Nonculturable Salmonella enterica Serovar Typhimurium DT104†". Applied and Environmental Microbiology 69, n.º 11 (noviembre de 2003): 6669–75. http://dx.doi.org/10.1128/aem.69.11.6669-6675.2003.
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ABSTRACT Salmonella enterica serovar Typhimurium DT104 11601was tested for its ability to maintain viability in minimal, chemically defined solutions. Periodic monitoring of growth and survival in microcosms of different ion concentrations, maintained at various temperatures, showed a gradual decline in culturable organisms (∼235 days) at 5°C. Organisms maintained at a higher temperature (21°C) showed continuous, equivalent CFU per milliliter (∼106) up to 400 days after inoculation. Fluorescence microscopy with Baclight revealed that nonculturable cells were actually viable, while observations with scanning electron microscopy showed that the cells had retained their structural integrity. Temperature upshift (56°C ± 0.5, 15 s) of the nonculturable organisms (5°C) in Trypticase soy broth followed by immediate inoculation onto Trypticase soy agar (TSA) gave evidence of resuscitation. Interestingly, S. enterica serovar Typhimurium DT104 from the microcosms at either 5°C (1 to 200 days) or 21°C (1 to 250 days) did not show enhanced growth after intermittent inoculation onto catalase-supplemented TSA. Furthermore, cells from 21°C microcosms exposed to oxidative and osmotic stress showed greater resistance to stresses over increasing times of exposure than did recently grown cells. It is possible that the exceptional survivability and resilience of this particular strain may in part reflect the growing importance of this multidrug-resistant organism, in general, as a cause of intestinal disease in humans. The fact that S. enterica serovar Typhimurium DT104 11601 is capable of modifying its physiological characteristics, including entry into and recovery from the viable but nonculturable state, suggests the overall possibility that S. enterica serovar Typhimurium DT104 may be able to respond uniquely to various adverse environmental conditions.
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Andrews Jr., Robert E., Wesley S. Johnson, Abby R. Guard y Jonathan D. Marvin. "Survival of enterococci and Tn916-like conjugative transposons in soil". Canadian Journal of Microbiology 50, n.º 11 (1 de noviembre de 2004): 957–66. http://dx.doi.org/10.1139/w04-090.
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The persistence of Enterococcus faecalis, fecal enterococci from swine waste, and Tn916-like elements was determined following inoculation into autoclaved and native soil microcosms. When cells of E. faecalis CG110 (Tn916) were inoculated into native microcosms, enterococcal viability in the soil decreased approximately 5 orders of magnitude (4.8 × 105CFU/g soil to < 10 CFU/g) after 5 weeks. In autoclaved microcosms, the viability of E. faecalis decreased by only 20% in 5 weeks. In contrast, the content of Tn916, based on PCR of DNA extracts from soil microcosms, decreased by about 20% in both native and autoclaved microcosms. Similar results were obtained when the source of fecal enterococci and Tn916-like elements was swine waste. Because the concentration of Tn916-independent E. faecalis DNA (the D-alanine D-alanine ligase gene), based on PCR, decreased to nearly undetectable levels (at least 3 orders of magnitude) after 5 weeks in the native microcosms, the evidence suggests Tn916 stability in the soil results from en masse transfer of the transposon to the normal soil microflora and not survival of E. faecalis DNA in the soil system. Results from denaturing gradient gel electrophoresis suggest that multiple forms of Tn916 occur in swine waste, but only forms most like Tn916 exhibit stability in the soil.Key words: Tn916, Enterococcus faecalis, soil, antibiotic resistance, conjugation, transposon.
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Röling, Wilfred F. M., Ivana R. Couto de Brito, Richard P. J. Swannell y Ian M. Head. "Response of Archaeal Communities in Beach Sediments to Spilled Oil and Bioremediation". Applied and Environmental Microbiology 70, n.º 5 (mayo de 2004): 2614–20. http://dx.doi.org/10.1128/aem.70.5.2614-2620.2004.
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ABSTRACT While the contribution of Bacteria to bioremediation of oil-contaminated shorelines is well established, the response of Archaea to spilled oil and bioremediation treatments is unknown. The relationship between archaeal community structure and oil spill bioremediation was examined in laboratory microcosms and in a bioremediation field trial. 16S rRNA gene-based PCR and denaturing gradient gel analysis revealed that the archaeal community in oil-free laboratory microcosms was stable for 26 days. In contrast, in oil-polluted microcosms a dramatic decrease in the ability to detect Archaea was observed, and it was not possible to amplify fragments of archaeal 16S rRNA genes from samples taken from microcosms treated with oil. This was the case irrespective of whether a bioremediation treatment (addition of inorganic nutrients) was applied. Since rapid oil biodegradation occurred in nutrient-treated microcosms, we concluded that Archaea are unlikely to play a role in oil degradation in beach ecosystems. A clear-cut relationship between the presence of oil and the absence of Archaea was not apparent in the field experiment. This may have been related to continuous inoculation of beach sediments in the field with Archaea from seawater or invertebrates and shows that the reestablishment of Archaea following bioremediation cannot be used as a determinant of ecosystem recovery following bioremediation. Comparative 16S rRNA sequence analysis showed that the majority of the Archaea detected (94%) belonged to a novel, distinct cluster of group II uncultured Euryarchaeota, which exhibited less than 87% identity to previously described sequences. A minor contribution of group I uncultured Crenarchaeota was observed.
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Barriault, Diane y Michel Sylvestre. "Factors affecting PCB degradation by an implanted bacterial strain in soil microcosms". Canadian Journal of Microbiology 39, n.º 6 (1 de junio de 1993): 594–602. http://dx.doi.org/10.1139/m93-086.
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Pseudomonas testosteroni B-356 was able to degrade approximately 50% of the Aroclor 1242 mixture in shaken culture. The aims of the present study were to evaluate the capabilities of this bacterial strain to degrade PCBs in soil microcosms and to identify some of the factors likely to favor the degradative performance of the implanted bacteria. The presence of biphenyl as cosubstrate was the most important factor affecting PCB degradation in soil. However, because biphenyl was rapidly depleted in soil microcosms, repeated addition of small amounts of biphenyl to maintain a constant level of the cosubstrate allowed the achievement of a higher degree of degradation of the tetrachlorinated components of Aroclor 1242 than was achieved with a single addition at the time of inoculation. Degradation of di- and tri-chlorinated PCB congeners was less affected by repeated addition of biphenyl because these congeners were degraded very fast and complete degradation was achieved before biphenyl was depleted in the soil. Biodegradation was also related to bioavailability of the substrate. We observed that the proportion of each congener degraded was higher in the microcosms receiving both the producer of the surface-active agent, Alcaligenes faecalis B-556, and strain B-356. Under the best conditions (presence of a constant level of biphenyl and of strain B-556) P. testosteroni B-356 was able to degrade approximately 30% of the Aroclor 1242 added to soil microcosms; some other factors reducing the PCB degradation capabilities of the implanted bacteria are also discussed.Key words: Aroclor 1242, biodegradation, bioremediation, Pseudomonas, soil.
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ANEES, MUHAMMAD, MUHAMMAD ABID, SOBIA CHOHAN, MUHAMMAD JAMIL, NADEEM AHMED, LIXIN ZHANG y EUI SHIK RHA. "In situ Impact of the Antagonistic Fungal Strain, Trichoderma gamsii T30 on the Plant Pathogenic Fungus, Rhizoctonia solani in Soil". Polish Journal of Microbiology 68, n.º 2 (10 de junio de 2019): 211–16. http://dx.doi.org/10.33073/pjm-2019-021.
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Rhizoctonia solani is a soil-borne fungus causing a wide range of plants diseases. Trichoderma gamsii strain T30 has previously been reported as antagonistic against R. solani. Although there are a few studies about the influence of Trichoderma strains on the R. solani densityin a pathosystem in the presence of plant hosts, this report for the first time comprehensively describes in situ effects of a T. gamsii strain on the population density of R. solani in the soil microcosmic conditions. The population dynamics of R. solani were followed in the autoclaved and non-autoclaved soils in artificially prepared microcosms up to day 25 after co-inoculation with T. gamsii in the variable ratios (R1/T1; R1/T0.1; R1/T0.01 of R. solani/T. gamsii). The population density of R. solani was evaluated by qPCR. In the autoclaved soil, target DNA copies of R. solani increased in the control samples from 1 × 105 to 6.5 × 106. At R1/T0.01, the number of target DNA copies were not significantly changed until day 11; however, it decreased by around five times at day 25. At R1/T0.1 and R1/T1, the number of DNA copies was reduced to 2.1 × 106 and 7.6 × 105 at day 11, respectively and the reduction was as much as 17 times at day 25. In the non-autoclaved soil, the number of the fungal cells decreased at day 25 whether inoculated or not with Trichoderma indicating a general suppression by the soil microbiome. In brief, T. gamsii significantly inhibited the growth of R. solani in the soil in situ and there was a general suppressive effect of the natural microbiome.
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Machado-Moreira, Bernardino, Karl Richards, Florence Abram, Fiona Brennan, Michael Gaffney y Catherine M. Burgess. "Survival of Escherichia coli and Listeria innocua on Lettuce after Irrigation with Contaminated Water in a Temperate Climate". Foods 10, n.º 9 (2 de septiembre de 2021): 2072. http://dx.doi.org/10.3390/foods10092072.
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Microbial disease outbreaks related to fresh produce consumption, including leafy green vegetables, have increased in recent years. Where contamination occurs, pathogen persistence may represent a risk for consumers’ health. This study analysed the survival of E. coli and L. innocua on lettuce plants watered with contaminated irrigation water via a single irrigation event and within stored irrigation water. Separate lettuce plants (Lactuca sativa var. capitata) were irrigated with water spiked with Log10 7 cfu/mL of each of the two strains and survival assessed via direct enumeration, enrichment and qPCR. In parallel, individual 20 L water microcosms were spiked with Log10 7 cfu/mL of the individual strains and sampled at similar time points. Both strains were observed to survive on lettuce plants up to 28 days after inoculation. Direct quantification by culture methods showed a Log10 4 decrease in the concentration of E. coli 14 days after inoculation, and a Log10 3 decrease in the concentration of L. innocua 10 days after inoculation. E. coli was detected in water samples up to 7 days after inoculation and L. innocua was detected up to 28 days by direct enumeration. Both strains were recovered from enriched samples up to 28 days after inoculation. These results demonstrate that E. coli and L. innocua strains are able to persist on lettuce after a single contamination event up until the plants reach a harvestable state. Furthermore, the persistence of E. coli and L. innocua in water for up to 28 days after inoculation illustrates the potential for multiple plant contamination events from stored irrigation water, emphasising the importance of ensuring that irrigation water is of a high quality.
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FELS, D., M. VIGNON y O. KALTZ. "Ecological and genetic determinants of multiple infection and aggregation in a microbial host-parasite system". Parasitology 135, n.º 12 (8 de septiembre de 2008): 1373–83. http://dx.doi.org/10.1017/s0031182008004940.
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SUMMARYThe number of parasites colonizing a host (termed ‘multiple infection’) is an important determinant of host-parasite interactions. In theory, multiple infection is determined by random mass action in genetically and spatially homogeneous populations of host and parasite. In real populations, deviations from these assumptions may strongly influence levels of multiple infection. We carried out inoculation experiments in microcosms of the freshwater protozoan Paramecium caudatum and its bacterial parasite Holospora undulata. Increasing parasite dose produced higher levels of (multiple) infection; more susceptible host genotypes also were more multiply infected. An overall pattern of parasite aggregation (excess of uninfected individuals and of individuals carrying larger numbers of parasites) indicated deviations from random mass-action transmission. Homogenizing spatial distributions of parasite and host in our microcosms did not affect aggregation, whereas aggregation was more pronounced in old than in new host clones. Thus, variation in susceptibility may arise over time within clonal populations. When sequentially inoculated, already established infections increased the probability of additional infection in generally resistant host clones, but decreased it in more susceptible clones. Hence, the role of multiple infection as a driver of epidemiological or evolutionary processes may vary among populations, depending on their precise genetic composition or infection history.
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Portell, Xavier, Carol Verheecke-Vaessen, Rosa Torrelles-Ràfales, Angel Medina, Wilfred Otten, Naresh Magan y Esther García-Cela. "Three-Dimensional Study of F. graminearum Colonisation of Stored Wheat: Post-Harvest Growth Patterns, Dry Matter Losses and Mycotoxin Contamination". Microorganisms 8, n.º 8 (1 de agosto de 2020): 1170. http://dx.doi.org/10.3390/microorganisms8081170.
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Fusarium causes significant post-harvest quality losses and mycotoxin contamination in stored wheat but the colonisation dynamics of the grain and how this may be affected by the initial inoculum position in the grain mass is poorly understood. This study examined the 3D growth kinetics and mycotoxin production (deoxynivalenol and zearalenone) by F. graminearum during hyphal colonisation from different initial inoculum positions in wheat microcosms (top-centre, bottom-centre, and bottom-side) maintained at two water activities (aw; 0.95 and 0.97). Clear jars were used to visually follow the colonisation dynamics. Fungal respiration and associated dry matter loss (DML) and ergosterol were also quantified. Colonisation dynamics was shown to be affected by the inoculation position. At the end of the colonisation process, fungal respiration and DML were driven by the inoculation position, and the latter also by the prevailing aw. Fungal biomass (ergosterol) was mainly affected by the aw. The initial inoculum position did not affect the relative mycotoxin production. There was a positive correlation between respiration and ergosterol, and between mycotoxin production and colonisation indicators. We suggest that spatially explicit predictive models can be used to better understand the colonisation patterns and mycotoxin contamination of stored cereal commodities and to aid more effective post-harvest management.
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Lettice, Eoin P. y Peter W. Jones. "Evaluation of rhizobacterial colonisation and the ability to induce Globodera pallida hatch". Nematology 17, n.º 2 (2015): 203–12. http://dx.doi.org/10.1163/15685411-00002863.
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Three bacterial isolates, SB13 (Acinetobacter sp.), SB14 (Arthrobacter sp.) and SB15 (Bacillus sp.), were previously isolated from the rhizosphere of sugar beet (Beta vulgaris ssp. vulgaris) plants and shown to increase hatch of potato cyst nematodes in vitro. In this study, the three isolates were assayed for rhizosphere competence. Each isolate was applied to seeds at each of four concentrations (105-108 CFU ml−1) and the inoculated seeds were planted in plastic microcosms containing coarse sand. All three isolates were shown to colonise the rhizosphere, although to differing degrees, with the higher inoculation densities providing significantly better colonisation. The isolates increased sugar beet root and shoot dry weight. Isolates SB14 and SB15 were analysed for their ability to induce in vivo hatch of Globodera pallida in non-sterile soil planted with sugar beet. After 4 and 6 weeks, both isolates had induced significantly greater percentage hatch compared to controls.
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O'Callaghan, M., E. Gerard y V. W. Johnson. "Effect of soil moisture and temperature on survival of microbial control agents". New Zealand Plant Protection 54 (1 de agosto de 2001): 128–35. http://dx.doi.org/10.30843/nzpp.2001.54.3753.
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Microbial control of soil dwelling pests and pathogens depends on the survival of microbial inocula in soil Three microbes Beauveria bassiana A6 Serratia entomophila 626 and Pseudomonas fluorescens CHA0Rif were inoculated into soil microcosms at three soil moistures and temperatures Survival was determined at regular intervals Beauveria bassiana survived well in soil; after 3 months the populations were maintained at levels close to those immediately following inoculation under most soil conditions Serratia entomophila and P fluorescens populations declined gradually Soil moisture impacted on survival of P fluorescens with populations declining most rapidly in the dry soil at all temperatures Pseudomonas fluorescens was not recovered after 54 days at 20C The rate of population decline of S entomophila increased with soil temperature but populations remained above the minimum level of detection after three months with soil moisture having little effect on survival Formulation of S entomophila into granules greatly improved the survival of this bacterium in soil
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Mercier, A., C. Michel, C. Joulian, S. Touzé, L. Amalric, P. Bataillard, C. Morlay y F. Battaglia-Brunet. "Decrease of the level of extractable polychlorinated biphenyls in soil microcosms: Influence of granular activated carbon and inoculation by natural microbial consortia". International Biodeterioration & Biodegradation 105 (noviembre de 2015): 127–36. http://dx.doi.org/10.1016/j.ibiod.2015.08.024.
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Thion, Cécile, Aurélie Cébron, Thierry Beguiristain y Corinne Leyval. "Inoculation of PAH-degrading strains of Fusarium solani and Arthrobacter oxydans in rhizospheric sand and soil microcosms: microbial interactions and PAH dissipation". Biodegradation 24, n.º 4 (30 de marzo de 2013): 569–81. http://dx.doi.org/10.1007/s10532-013-9628-3.
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Vilain, Sébastien, Yun Luo, Michael B. Hildreth y Volker S. Brözel. "Analysis of the Life Cycle of the Soil Saprophyte Bacillus cereus in Liquid Soil Extract and in Soil". Applied and Environmental Microbiology 72, n.º 7 (julio de 2006): 4970–77. http://dx.doi.org/10.1128/aem.03076-05.
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ABSTRACT Bacillus is commonly isolated from soils, with organisms of Bacillus cereus sensu lato being prevalent. Knowledge of the ecology of B. cereus and other Bacillus species in soil is far from complete. While the older literature favors a model of growth on soil-associated organic matter, the current paradigm is that B. cereus sensu lato germinates and grows in association with animals or plants, resulting in either symbiotic or pathogenic interactions. An in terra approach to study soil-associated bacteria is described, using filter-sterilized soil-extracted soluble organic matter (SESOM) and artificial soil microcosms (ASM) saturated with SESOM. B. cereus ATCC 14579 displayed a life cycle, with the ability to germinate, grow, and subsequently sporulate in both the liquid SESOM extract and in ASM inserted into wells in agar medium. Cells grew in liquid SESOM without separating, forming multicellular structures that coalesced to form clumps and encasing the ensuing spores in an extracellular matrix. Bacillus was able to translocate from the point of inoculation through soil microcosms as shown by the emergence of outgrowths on the surrounding agar surface. Microscopic inspection revealed bundles of parallel chains inside the soil. The motility inhibitor l-ethionine failed to suppress outgrowth, ruling out translocation by a flagellar-mediated mechanism such as swimming or swarming. Bacillus subtilis subsp. subtilis Marburg and four Bacillus isolates taken at random from soils also displayed a life cycle in SESOM and ASM and were all able to translocate through ASM, even in presence of l-ethionine. These data indicate that B. cereus is a saprophytic bacterium that is able to grow in soil and furthermore that it is adapted to translocate by employing a multicellular mode of growth.
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Banihashemi, Avid, Michele I. Van Dyke y Peter M. Huck. "Application of long amplicon propidium monoazide-PCR to assess the effects of temperature and background microbiota on pathogens in river water". Journal of Water and Health 15, n.º 3 (24 de febrero de 2017): 418–28. http://dx.doi.org/10.2166/wh.2017.161.
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The decay rates of enteric waterborne pathogens were evaluated following the introduction of Yersinia enterocolitica, Salmonella enterica, Campylobacter jejuni and Arcobacter butzleri into river water at different temperatures (5, 15 and 25°C) for a period of 28 days. To improve the accuracy of the results a molecular viability assay, long amplicon propidium monoazide-polymerase chain reaction (PMA-PCR), was used to quantify the viable cell concentration and results from PCR with and without PMA were compared. As well, the effect of background microbiota was assessed for Y. enterocolitica and S. enterica by inoculating cells into sterile and non-sterile river water. Cell persistence was improved by up to 4 log for Y. enterocolitica and 4.5 log for S. enterica in sterile river water compared to natural river water, showing that the autochthonous biological activity in river water can accelerate the die-off of introduced bacteria. Results also showed that low temperature significantly improved the persistence of all four target bacteria in non-sterile river water. There was a more rapid decline in cell concentration in samples with PMA pretreatment; therefore using PMA-PCR analysis can provide more reliable data on viable/active enteric bacteria in aquatic microcosms and allows for improved assessment of pathogens in the environment.
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John Hendel, Edward Topp,, Zexun Lu y Ralph Chapman. "Biodegradation of caffeine in agricultural soil". Canadian Journal of Soil Science 86, n.º 3 (1 de mayo de 2006): 533–44. http://dx.doi.org/10.4141/s05-064.
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Caffeine (1,3,7-trimethylxanthine) could represent a useful marker of contamination of effluent from agricultural land receiving biosolids. The persistence characteristics of caffeine in three agricultural soils was investigated. In laboratory microcosms of moist soil incubated at 30°C, [8-ring-14C]-caffeine was rapidly and thoroughly mineralized to 14CO2 in a sandy loam and a loam soil, and less rapidly in a silt loam soil. Caffeine mineralization was very responsive to soil temperature and moisture. Mineralization of caffeine was hastened by the addition of liquid municipal biosolids (LMB) from three municipal sewage-treatment plants (MSTPs) that aerate this material. In contrast, LMB from three MSTPs that did not aerobically digest their LMB did not accelerate caffeine mineralization. Autoclaved LMB had no effect on caffeine dissipation. Abacterium, designated Pseudomonas sp. Strain TH1, was isolated from aerated LMB. The bacterium first demethylated caffeine to 3,7-dimethylxanthine, and then mineralized the molecule. Inoculation of Pseudomonas sp. Strain TH1 into soil hastened mineralization of [8-ring-14C]-caffeine. In summary, caffeine was more stable in a silt loam soil than a sandy loam or loam soil, but biodegradation in all three soils was quite uniform upon the addition of caffeine-degrading bacteria or aerated biosolids. We suggest that caffeine would likely not be a suitably conservative chemical marker for detecting chronic contamination of agricultural drainage water following fertilization wit hLMB. Aerobic digestion of LMB promotes the enrichment of caffeine-degrading microorganisms. Key words: Caffeine biodegradation, biosolids chemical marker, biosolids organic contaminant, water quality
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Cosgrove, L., P. L. McGeechan, P. S. Handley y G. D. Robson. "Effect of Biostimulation and Bioaugmentation on Degradation of Polyurethane Buried in Soil". Applied and Environmental Microbiology 76, n.º 3 (30 de noviembre de 2009): 810–19. http://dx.doi.org/10.1128/aem.00534-09.
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ABSTRACT This work investigated biostimulation and bioaugmentation as strategies for removing polyurethane (PU) waste in soil. Soil microcosms were biostimulated with the PU dispersion agent “Impranil” and/or yeast extract or were bioaugmented with PU-degrading fungi, and the degradation of subsequently buried PU was determined. Fungal communities in the soil and colonizing buried PU were enumerated on solid media and were analyzed using denaturing gradient gel electrophoresis (DGGE). Biostimulation with yeast extract alone or in conjunction with Impranil increased PU degradation 62% compared to the degradation in untreated control soil and was associated with a 45% increase in putative PU degraders colonizing PU. Specific fungi were enriched in soil following biostimulation; however, few of these fungi colonized the surface of buried PU. Fungi used for soil bioaugmentation were cultivated on the surface of sterile wheat to form a mycelium-rich inoculum. Wheat, when added alone to soil, increased PU degradation by 28%, suggesting that wheat biomass had a biostimulating effect. Addition of wheat colonized with Nectria haematococca, Penicillium viridicatum, Penicillium ochrochloron, or an unidentified Mucormycotina sp. increased PU degradation a further 30 to 70%, suggesting that biostimulation and bioaugmentation were operating in concert to enhance PU degradation. Interestingly, few of the inoculated fungi could be detected by DGGE in the soil or on the surface of the PU 4 weeks after inoculation. Bioaugmentation did, however, increase the numbers of indigenous PU-degrading fungi and caused an inoculum-dependent change in the composition of the native fungal populations, which may explain the increased degradation observed. These results demonstrate that both biostimulation and bioaugmentation may be viable tools for the remediation of environments contaminated with polyurethane waste.
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Abdalla, O. A. y A. Ali. "First Report of Alfalfa mosaic virus Associated with Severe Mosaic and Mottling of Pepper (Capsicum annuum) and White Clover (Trifolium repens) in Oklahoma". Plant Disease 96, n.º 11 (noviembre de 2012): 1705. http://dx.doi.org/10.1094/pdis-07-12-0630-pdn.
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Alfalfa mosaic virus (AMV), a member of the genus Alfamovirus, family Bromoviridae (1), has been reported in 44 states in the United States excluding Oklahoma. During a cucurbit survey in the summer of 2010, severe mosaic and mottling symptoms were observed on many peppers (Capsicum annuum) and white clover (Trifolium repens) plants in Tulsa, Oklahoma. Symptomatic leaf samples from 15 pepper and two white clover plants were collected in the Bixby area and analyzed serologically by dot-immunobinding assay (DIBA) using specific polyclonal antibodies against AMV (Agdia, Inc). Seven out of 15 pepper samples and both white clover samples were tested positive by DIBA to AMV. The remaining symptomatic samples were positive to Cucumber mosaic virus (CMV). Total RNA was extracted from DIBA positive AMV samples by Tri-reagent method. A small aliquot of total RNA was tested by reverse transcription (RT)-PCR using specific primers: AMV-F 5′ GTCCGCGATCTCTTAAAT 3′ and AMV-R 5′ GAAGTTTGGGTCGAGAGA 3′ that were designed to amplify 900 bp of the AMV-RNA 3. Analysis of the PCR products on agarose gel electrophoreses showed that all tested samples showed a band of the expected size while DIBA negative AMV samples did not produce any band. The amplified PCR product (900 bp) obtained from pepper and white clover were cleaned with PCR purification kit (Qiagen, Germantown, MD) and directly sequenced bi-directionally using the above primers. Sequence analysis confirmed that this virus shared 97% identity at nucleotide sequence with RNA 3 of AMV isolate from Madison-USA (GenBank Accession No. K02703). For biological and morphological characterization of the virus, eight pepper plants were mechanically inoculated using 0.1 M K2HPO4 buffer (pH 7.2) with total RNA extracted from AMV positive pepper or white clover plant samples. One to two weeks post-inoculation, all inoculated plants produced severe mosaic, mottling, and stunting. Virus-like particles preparations were obtained from these symptomatic plants according to our previously described method (2) and electron microcopy examination showed typical AMV particles. These biological and morphological data further confirmed the presence of AMV infecting pepper and clover in Oklahoma. AMV is a significant pathogen worldwide and infects more than 600 species in 70 families, especially alfalfa, pepper, soybean, and tobacco (3). AMV has a worldwide distribution, including the United States, and particularly the Midwestern U.S. where the incidence of the virus is on the rise recently because of the presence of its vector (Aphis glycines) (4). To our knowledge, this is the first report of AMV infecting crops in Oklahoma, which could pose a threat to other economic crops grown in Oklahoma, especially soybean. References: (1) E. E. Mueller et al. Plant Dis. 91:266, 2007. (2) A. Ali et al. Plant Dis. 96:243, 2012. (3) J. F. Bol. Mol. Plant Path.4:1, 2003. (4) M. Malapi-Nelson et al. Plant Dis.93:1259, 2009.