Дисертації з теми "Mycotoxin"
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1
Müller-Placinta, Cristina-Mihaiela. "Factors affecting mycotoxin production by Fusarium species." Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/27077.
Анотація:
Studies were undertaken to investigate the factors affecting mycotoxin production in Fusarium phytopathogens. The conclusions of this work are divided into the following categories. Substantive findings: 1) Contamination of cereal grains with Fusarium mycotoxins is a global and continuing issue and is likely to remain so until a systematic elucidation of controlling factors has been accomplished. 2) An important observation at the commencement of the research programme examined the validity of using direct TLC analysis of agar culture plugs to establish mycotoxin profiles in Fusarium species. The results in this thesis indicate that this method only detected a limited number of mycotoxins and this was not consistent between surfaces of the plugs tested or between experiments in the preliminary series. 3) A noteworthy observation was that HT-2 toxin production from T-2 toxin was not time-related as claimed by other workers. There may be a real species differences in this respect between F.sporotrichioides and F. poae. 4) Mixtures of carbendazim and propiconazole or carbendazim plus maneb or carbendazim plus maneb plus tridemorph all enhanced T-2 toxin formation. 5) The fungicide-induced enhancement of mycotoxin production has now been extended for the first time to HT-2 toxin and NEO. 6) A substantive finding, not previously noted, is that difenoconazole failed to stimulate T-2 toxin formation at 25°C but was capable of transforming it to HT-2 toxin and then stimulating the production of the latter product. 7) Difenoconazole appears to be a fungicide in a class of its own in that DAS and NEO production are consistently higher than for a large majority of other fungicides tested. 8) NEO production was not substantially affected by fungal exposure to Bavistin, whereas carbendazim acted in a stimulatory manner. It is suggested that this discrepancy is due to fungicide form, an effect not previously reported.
2
Al-Julaifi, Mohammed Zaid Nasser. "Production of the mycotoxin patulin in nature." Thesis, University of Sheffield, 1995. http://etheses.whiterose.ac.uk/6048/.
Анотація:
A study was made of the factors governing the production of the mycotoxin patulin in nature, including biological and physiological factors. The objective of the research described in this thesis was to study the ability of the indigenous fungi of fruits and the apple rot fungus, Penicillium expansum, to grow and to produce patulin in different substrates, both natural (apples, sugar beet, wheat straw) and laboratory media. The effect of carbon and nitrogen sources and the relationship between the production of the toxin and nitrification and its action with the natural isolated bacteria and fungi was also investigated. Common members of the genus Penicillium were found to represent a high percentage of the indigenous fungal flora isolated from both apples and sugar beet. Most of these isolates were able to produce patulin in Czapek Dox liquid medium. Although both apple fruit and sugar beet were naturally highly contaminated with moulds, only apples were contaminated with patulin (7598 gg kg"). Confirmatory tests showed patulin production of 8.3% and 50% (after 7 days) to 99.2% (after 30 days) by the indigenous fungi in apple and sugar beet, respectively. The indigenous fungal flora of wheat straw failed to produce patulin when growing naturally. Patulin was produced only by Penicillium expansum alone and not when growing in association with the white rot fungus Phanerochaete chrysosporium. The accumulation of ammonium and nitrate during urea hydrolysis and ammonium nitrification by Penicillium sp (1), Penicillium sp (3) and Penicillim expansum was achieved with varying degree of efficiency. Urea hydrolysis, but not ammonium nitrification was associated with patulin production. Growth of P. expansum and Penicillium species (1 and 3) occurred under oligotrophic conditions. Both carbon and nitrogen are required for patulin production but it is the depletion of nitrogen which is important for production of the toxin.
3
Petchkongkaew, Awanwee. "Reduction of mycotoxin contamination level during soybean fermentation." Phd thesis, Toulouse, INPT, 2008. http://oatao.univ-toulouse.fr/7713/1/petchkongkaew.pdf.
Анотація:
This thesis deals with the reduction of mycotoxin contamination level during soybean fermentation (Thua-Nao). Beside this work, isolation, characterization, and ochratoxin A production ability of toxigenic fungi from French grapes were also study. Results of this latter part showed that Aspergillus carbonarius and Aspergillus niger are the most ochratoxin A producer in wine grape from France. Furthermore, Aspergillus japonicus can produce a little bit quantity of ochratoxin A in wine grape too. Regarding to the main part of the work, 23 isolates of Bacillus spp. were isolated from Thai Thua-Nao. An Aspergillus flavus aflatoxin producing strain was also isolated from Thua-Nao whereas an Aspergillus westerdijkiae was chosen as an OTA producing reference strain. The objectives were to find an efficient Bacillus strain for: Growth inhibition of Aspergillus flavus and Aspergillus westerdijkiae NRRL 3174. - Limitation of aflatoxin B1 production. ; - Mycotoxins, aflatoxin B1 and ochratoxin A detoxification. Among the results, Bacillus CM 21, which was identified later by ITS sequencing as Bacillus licheniformis, showed the highest ability on inhibition of growth of both Aspergillus strains and both of mycotoxins removal (decrease of 74% of AFB1 and 92.5% of OTA). Another Bacillus strain, MHS 13, inhibiting both Aspergillus growth and detoxifying 85% of AFB1 was identified as Bacillus subtilis. Finally, culture supernatant and cellular extract from both interested Bacillus strains were tested for aflatoxin B1 and ochratoxin A degradation ability in order to know their degradation mechanisms. Moreover, study on optimal condition for aflatoxin B1 and ochratoxin A degradation were also conducted. All results indicated that OTA was significantly degraded by culture supernatant from Bacillus licheniformis CM 21 (p lower than 0.0001) in OTalpha. The percentage of OTA degradation was 97.5% and the optimal activity of its culture supernatant was found at pH 7.0 and 37°C with 24 h culture incubation time and 2 h contact time. Moreover, OTA was also significantly degraded by culture supernatant from Bacillus subtilis MHS 13 (p lower than 0.0017) at pH 5.0 and 37°C with 48 h culture incubation time and 2 h contact time. The proposed degradation mechanism should be extracellular and carboxypeptidase A probably responsible for this degradation since no activity was found for the intracellular extract. However, AFB1 could be degraded by neither culture supernatant nor cellular extract from both of these microorganisms. Hence, the AFB1 detoxification mechanism may be due to non-enzymatic mechanism.
4
Imathiu, Samuel Mutembei. "Fusarium langsethiae infection and mycotoxin production in oats." Thesis, Harper Adams University College, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492005.
Анотація:
In this investigation aimed to identify and understand the fungus responsible for the production ofHT-2 and T-2 mycotoxins in UK oats, Fusarium langsethiae was found to be the causal species. A quantitative competitive PCR (QC-PCR) and a real-time PCR assay for quantifying F langsethiae biomass in plant material were successfully developed. Real-time PCR was found to have a wider range of quantification than QC-PCR. In glasshouse experiments, point inoculation technique and high spore load (106 spores mr)) were found to significantly increase (P = 0.036 and 0.016 respectively) the level of F langsethiae infection in oat panicles. HT-2 and T-2 appeared to increase in line with the level of infection. For both glasshouse and field experiments, all inoculatiQn methods failed to achieve high levels of infection and high levels of HT-2 and T-2 observed in some commercial fields. Detached leaf assays showed some host preference of F langsethiae towards oats than wheat. Lesion lengths were longest on leaves of an oat cultivar (Gerald) that has been reported to accumulate highest HT-2 and T-2 and shortest on leaves of the cultivar (Millennium) reported to accumulate the lowest levels of these mycotoxins. Fusarium langsethiae was not found to be a seedling blight pathogen of oats and wheat in a controlled environment study comparing its pathogenicity with those of known Fusariu11l and Microdochiu11l species. Fusariu11l langsethiae is therefore unlikely to reduce crop stand and yield where infected seeds are sown. Fusariu11l langsethiae failed to produce visual symptoms in infected oat panicles or wheat ears in all experiments and in commercial oat fields surveyed. However, all evidence indicates that it is responsible for high concentrations of HT-2 and T-2 in oats, consequently the presence of this fungus in oats is important in human and animal health.
5
Petchkongkaew, Awanwee Gasaluck Piyawan Lebrihi Ahmed Taillandier Patricia. "Reduction of mycotoxin contamination level during soybean fermentation." Toulouse : INP Toulouse, 2008. http://ethesis.inp-toulouse.fr/archive/00000653.
Анотація:
Reproduction de : Thèse de doctorat : Microbiologie et Biocatalyse industrielles : Toulouse, INPT : 2008. Reproduction de : Thèse de doctorat : Microbiologie et Biocatalyse industrielles : Suranaree, SUT : 2008.Thèse soutenue en cotutelle. Titre provenant de l'écran-titre.
6
Pizzamiglio, Valentina <1979>. "Nutritional strategies to control mycotoxin damages in swine." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/1061/1/Tesi_Pizzamiglio_Valentina.pdf.
Анотація:
Mycotoxins are contaminants of agricultural products both in the field and during storage and
can enter the food chain through contaminated cereals and foods (milk, meat, and eggs)
obtained from animals fed mycotoxin contaminated feeds. Mycotoxins are genotoxic
carcinogens that cause health and economic problems. Ochratoxin A and fumonisin B1 have
been classified by the International Agency for Research on Cancer in 1993, as “possibly
carcinogenic to humans” (class 2B).
To control mycotoxins induced damages, different strategies have been developed to reduce
the growth of mycotoxigenic fungi as well as to decontaminate and/or detoxify mycotoxin
contaminated foods and animal feeds. Critical points, target for these strategies, are:
prevention of mycotoxin contamination, detoxification of mycotoxins already present in food
and feed, inhibition of mycotoxin absorption in the gastrointestinal tract, reduce mycotoxin
induced damages when absorption occurs. Decontamination processes, as indicate by FAO,
needs the following requisites to reduce toxic and economic impact of mycotoxins: it must
destroy, inactivate, or remove mycotoxins; it must not produce or leave toxic and/or
carcinogenic/mutagenic residues in the final products or in food products obtained from
animals fed decontaminated feed; it must be capable of destroying fungal spores and
mycelium in order to avoiding mycotoxin formation under favorable conditions; it should not
adversely affect desirable physical and sensory properties of the feedstuff; it has to be
technically and economically feasible. One important approach to the prevention of
mycotoxicosis in livestock is the addition in the diets of the non-nutritionally adsorbents that
bind mycotoxins preventing the absorption in the gastrointestinal tract. Activated carbons,
hydrated sodium calcium aluminosilicate (HSCAS), zeolites, bentonites, and certain clays, are
the most studied adsorbent and they possess a high affinity for mycotoxins. In recent years,
there has been increasing interest on the hypothesis that the absorption in consumed food can
be inhibited by microorganisms in the gastrointestinal tract. Numerous investigators showed
that some dairy strains of LAB and bifidobacteria were able to bind aflatoxins effectively.
There is a strong need for prevention of the mycotoxin-induced damages once the toxin is
ingested. Nutritional approaches, such as supplementation of nutrients, food components, or
additives with protective effects against mycotoxin toxicity are assuming increasing interest.
Since mycotoxins have been known to produce damages by increasing oxidative stress, the
protective properties of antioxidant substances have been extensively investigated.
Purpose of the present study was to investigate in vitro and in vivo, strategies to counteract
mycotoxin threat particularly in swine husbandry. The Ussing chambers technique was
applied in the present study that for the first time to investigate in vitro the permeability of
OTA and FB1 through rat intestinal mucosa. Results showed that OTA and FB1 were not
absorbed from rat small intestine mucosa. Since in vivo absorption of both mycotoxins
normally occurs, it is evident that in these experimental conditions Ussing diffusion chambers
were not able to assess the intestinal permeability of OTA and FB1. A large number of LAB
strains isolated from feces and different gastrointestinal tract regions of pigs and poultry were
screened for their ability to remove OTA, FB1, and DON from bacterial medium. Results of
this in vitro study showed low efficacy of isolated LAB strains to reduce OTA, FB1, and
DON from bacterial medium. An in vivo trial in rats was performed to evaluate the effects of
in-feed supplementation of a LAB strain, Pediococcus pentosaceus FBB61, to counteract the
toxic effects induced by exposure to OTA contaminated diets. The study allows to conclude
that feed supplementation with P. pentosaceus FBB61 ameliorates the oxidative status in
liver, and lowers OTA induced oxidative damage in liver and kidney if diet was contaminated
by OTA. This P. pentosaceus FBB61 feature joined to its bactericidal activity against Gram
positive bacteria and its ability to modulate gut microflora balance in pigs, encourage
additional in vivo experiments in order to better understand the potential role of P.
pentosaceus FBB61 as probiotic for farm animals and humans. In the present study, in vivo
trial on weaned piglets fed FB1 allow to conclude that feeding of 7.32 ppm of FB1 for 6
weeks did not impair growth performance. Deoxynivalenol contamination of feeds was
evaluated in an in vivo trial on weaned piglets. The comparison between growth parameters of
piglets fed DON contaminated diet and contaminated diet supplemented with the commercial
product did not reach the significance level but piglet growth performances were numerically
improved when the commercial product was added to DON contaminated diet. Further studies
are needed to improve knowledge on mycotoxins intestinal absorption, mechanism for their
detoxification in feeds and foods, and nutritional strategies to reduce mycotoxins induced
damages in animals and humans. The multifactorial approach acting on each of the various
steps could be a promising strategy to counteract mycotoxins damages.
7
Pizzamiglio, Valentina <1979>. "Nutritional strategies to control mycotoxin damages in swine." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/1061/.
Анотація:
Mycotoxins are contaminants of agricultural products both in the field and during storage and
can enter the food chain through contaminated cereals and foods (milk, meat, and eggs)
obtained from animals fed mycotoxin contaminated feeds. Mycotoxins are genotoxic
carcinogens that cause health and economic problems. Ochratoxin A and fumonisin B1 have
been classified by the International Agency for Research on Cancer in 1993, as “possibly
carcinogenic to humans” (class 2B).
To control mycotoxins induced damages, different strategies have been developed to reduce
the growth of mycotoxigenic fungi as well as to decontaminate and/or detoxify mycotoxin
contaminated foods and animal feeds. Critical points, target for these strategies, are:
prevention of mycotoxin contamination, detoxification of mycotoxins already present in food
and feed, inhibition of mycotoxin absorption in the gastrointestinal tract, reduce mycotoxin
induced damages when absorption occurs. Decontamination processes, as indicate by FAO,
needs the following requisites to reduce toxic and economic impact of mycotoxins: it must
destroy, inactivate, or remove mycotoxins; it must not produce or leave toxic and/or
carcinogenic/mutagenic residues in the final products or in food products obtained from
animals fed decontaminated feed; it must be capable of destroying fungal spores and
mycelium in order to avoiding mycotoxin formation under favorable conditions; it should not
adversely affect desirable physical and sensory properties of the feedstuff; it has to be
technically and economically feasible. One important approach to the prevention of
mycotoxicosis in livestock is the addition in the diets of the non-nutritionally adsorbents that
bind mycotoxins preventing the absorption in the gastrointestinal tract. Activated carbons,
hydrated sodium calcium aluminosilicate (HSCAS), zeolites, bentonites, and certain clays, are
the most studied adsorbent and they possess a high affinity for mycotoxins. In recent years,
there has been increasing interest on the hypothesis that the absorption in consumed food can
be inhibited by microorganisms in the gastrointestinal tract. Numerous investigators showed
that some dairy strains of LAB and bifidobacteria were able to bind aflatoxins effectively.
There is a strong need for prevention of the mycotoxin-induced damages once the toxin is
ingested. Nutritional approaches, such as supplementation of nutrients, food components, or
additives with protective effects against mycotoxin toxicity are assuming increasing interest.
Since mycotoxins have been known to produce damages by increasing oxidative stress, the
protective properties of antioxidant substances have been extensively investigated.
Purpose of the present study was to investigate in vitro and in vivo, strategies to counteract
mycotoxin threat particularly in swine husbandry. The Ussing chambers technique was
applied in the present study that for the first time to investigate in vitro the permeability of
OTA and FB1 through rat intestinal mucosa. Results showed that OTA and FB1 were not
absorbed from rat small intestine mucosa. Since in vivo absorption of both mycotoxins
normally occurs, it is evident that in these experimental conditions Ussing diffusion chambers
were not able to assess the intestinal permeability of OTA and FB1. A large number of LAB
strains isolated from feces and different gastrointestinal tract regions of pigs and poultry were
screened for their ability to remove OTA, FB1, and DON from bacterial medium. Results of
this in vitro study showed low efficacy of isolated LAB strains to reduce OTA, FB1, and
DON from bacterial medium. An in vivo trial in rats was performed to evaluate the effects of
in-feed supplementation of a LAB strain, Pediococcus pentosaceus FBB61, to counteract the
toxic effects induced by exposure to OTA contaminated diets. The study allows to conclude
that feed supplementation with P. pentosaceus FBB61 ameliorates the oxidative status in
liver, and lowers OTA induced oxidative damage in liver and kidney if diet was contaminated
by OTA. This P. pentosaceus FBB61 feature joined to its bactericidal activity against Gram
positive bacteria and its ability to modulate gut microflora balance in pigs, encourage
additional in vivo experiments in order to better understand the potential role of P.
pentosaceus FBB61 as probiotic for farm animals and humans. In the present study, in vivo
trial on weaned piglets fed FB1 allow to conclude that feeding of 7.32 ppm of FB1 for 6
weeks did not impair growth performance. Deoxynivalenol contamination of feeds was
evaluated in an in vivo trial on weaned piglets. The comparison between growth parameters of
piglets fed DON contaminated diet and contaminated diet supplemented with the commercial
product did not reach the significance level but piglet growth performances were numerically
improved when the commercial product was added to DON contaminated diet. Further studies
are needed to improve knowledge on mycotoxins intestinal absorption, mechanism for their
detoxification in feeds and foods, and nutritional strategies to reduce mycotoxins induced
damages in animals and humans. The multifactorial approach acting on each of the various
steps could be a promising strategy to counteract mycotoxins damages.
8
Ncube, Edson. "Mycotoxin levels in subsistence farming systems in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/3801.
9
Pastorini, Elisabetta. "Analytical methodologies for evaluating mycotoxin contamination in food safety." Doctoral thesis, La Sapienza, 2006. http://hdl.handle.net/11573/916869.
10
Child, Christopher Jeremy. "Structural and functional studies on the 6-methylsalicylic acid synthase multienzyme complex from Penicillium patulum." Thesis, Queen Mary, University of London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369196.
11
Boupha, Prasongsidh C., of Western Sydney Hawkesbury University, and Faculty of Science and Technology. "Fate of the neurotoxic mycotoxin, cyclopiazonic acid in dairy products." THESIS_FST_XXX_Boupha_P.xml, 1998. http://handle.uws.edu.au:8081/1959.7/184.
Анотація:
The aim of the study in this thesis was to assess the stability of the mycotoxin, cyclopiazonic acid (CPA) in milk and dairy products processed from contaminated milk. A method was developed to detect CPA in milk and milk products using micellar electrokinetic capillary chromatography (MEKC), a technique of capillary electrophoresis (CE), which was rapid and non-labour-intensive. The quantifying efficiency of CE in detecting CPA was compared to Reverse Phase Liquid Chromatography. Heat-stability of CPA in milk was assessed under different conditions. A longer heat treatment of 60 degrees centigrade for 30 minutes led to a 10% decrease in the level of CPA. The results from this thesis demonstrate that CPA in milk at concentrations found in naturally contaminated milk could not be eliminated by the heat-treatment during milk processing, storage, processing and manufacture of dairy products. Occurrence of CPA in cheese curd, butter or cream following manufacture with contaminated milk was demonstrated. CPA is left in milk despite UV-visible radiation treatment with or without hydrogen peroxide and/or riboflavin. Chemical treatment, which is capable of completely eliminating CPA, is prohibited and impractical to use for milk treatment. Stability of CPA in milk and milk products confirms the potential of the toxin to reach consumers of dairy products.Doctor of Philosophy (PhD)
12
Daudi, Arsalan. "An exploration of Fusarium mycotoxin accumulation in hexaploid wheat germplasm." Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436463.
13
Boupha, Prasongsidh C. "Fate of the neurotoxic mycotoxin, cyclopiazonic acid in dairy products." Thesis, View thesis, 1998. http://handle.uws.edu.au:8081/1959.7/184.
Анотація:
The aim of the study in this thesis was to assess the stability of the mycotoxin, cyclopiazonic acid (CPA) in milk and dairy products processed from contaminated milk. A method was developed to detect CPA in milk and milk products using micellar electrokinetic capillary chromatography (MEKC), a technique of capillary electrophoresis (CE), which was rapid and non-labour-intensive. The quantifying efficiency of CE in detecting CPA was compared to Reverse Phase Liquid Chromatography. Heat-stability of CPA in milk was assessed under different conditions. A longer heat treatment of 60 degrees centigrade for 30 minutes led to a 10% decrease in the level of CPA. The results from this thesis demonstrate that CPA in milk at concentrations found in naturally contaminated milk could not be eliminated by the heat-treatment during milk processing, storage, processing and manufacture of dairy products. Occurrence of CPA in cheese curd, butter or cream following manufacture with contaminated milk was demonstrated. CPA is left in milk despite UV-visible radiation treatment with or without hydrogen peroxide and/or riboflavin. Chemical treatment, which is capable of completely eliminating CPA, is prohibited and impractical to use for milk treatment. Stability of CPA in milk and milk products confirms the potential of the toxin to reach consumers of dairy products.
14
Boupha, Prasongsidh C. "Fate of the neurotoxic mycotoxin, cyclopiazonic acid in dairy products /." View thesis, 1998. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030801.153613/index.html.
Анотація:
Thesis (Ph.D.) -- University of Western Sydney, Hawkesbury, 1998."A thesis presented to the University of Western Sydney for the degree of Doctor of Philosophy, September, 1998" Bibliography: leaves 193 - 219.
15
Beeton, S. "Biotransformation of T-2 toxin by bacterial communities." Thesis, University of Kent, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234437.
16
Bokhari, Fardos Marouf. "Studies on mycotoxin production by moulds in stored cereals and pulses." Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1463.
17
Rengifo, R. G. C. "Mycotoxin production in single and mixed microbial culture in cereal substrates." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381189.
18
Mooney, J. P. "The effect of relative humidity on mycotoxin production by Penicillium viridicum." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382428.
19
Abdelwahab, Emad Mohamad Nafie. "Ultrastructure of the normal and mycotoxin-treated liver in the duckling." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278365.
20
Itoba-Tombo, Elie Fereche. "Cyanogen and mycotoxin reduction for cassava (Manihot Esculenta Crantz) cultivated soil." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2666.
Анотація:
Thesis (DTech (Environmental-health))--Cape Peninsula University of Technology, 2018.The management of agricultural soil and its sustainable use, namely productivity, is paramount to the agricultural industry worldwide. Large-scale agricultural product producers and scientists emphasise using environmentally benign methods to increase agricultural production such as taking a green chemistry approach to agricultural activities and/or using cultivation techniques for the bio-augmentation of agricultural soil. Some of these agricultural products, such as cassava (Manihot esculenta), produce cyanogens which promote the infestation of a cyanogen-resistant microbial species known to produce mycotoxins during decomposition. Although cyanogens and mycotoxins are important components in the functioning of the earth system and agricultural soil, their cumulative effects can result in reduced soil productivity, hence degradation. Furthermore, the presence of mycotoxins in the environment and agricultural produce is hazardous to the environment, including the biotic communities in soil and humans. Therefore, an environmentally benign (green chemistry approach) method for the reduction of cyanogens and mycotoxins was proposed for this research study. The method investigated had to be applicable in-situ for the biodegradation of cyanogens and mycotoxins. Their reduction from decomposing cassava in cultivated soil, which can be used on a small and large scale, would mitigate deleterious effects of a less reported, unknown mycotoxins producer (fungal species), Cunninghamella bertholletiae (KT275316), found to be a free cyanide- (CN-) resistant isolate. The C. bertholletiae was isolated from decomposing cassava tubers and silt, subsequent to culturing on potato dextrose agar (PDA) and in an equivalent volume of nutrient broth (NB) containing KCN (4mg/40mL) at 30 °C for 120 hrs. The isolate demonstrated an ability to biodegrade CN- into NH3 and NO3. NH3 and NO3 are nitrogenous by-products produced when young cassava plants are cultivated in a controlled environment, with 80% of the initial CN- concentration being efficiently degraded to NH3/NO3 at a conversion rate of 77.5% and 72.5% (fungus from silt and cassava), respectively, within 120 hrs. From this research, it was observed that Sub-Saharan Africa is the largest contributor to the CN- load into the environment; from cassava cultivation as per FAO data. The quantity of CN- released was estimated at 0.025x10-3 to 6.71 ppq, with further increases of 60.5% being projected to be released into the environment by 2024. As such, it was hypothetically assumed that numerous species in cassava-cultivated soil become CN- resistant as they are exposed to CN- from decomposing cassava, becoming pathogenic thus antigonistic towards other biota in cassava-cultivated soil. Consequently, the pathogenicity of the isolate was investigated against organisms (n = 12) from cassava-cultivated soil. The isolate demonstrated inhibitory pathogenic activity against some soil bacterial communities such as Oligella ureolytica, Acinetobacter sp., Pseudomonas luteola and Sphingomonas paucimobilis. The isolate also demonstrated minor antagonistic effects against Myroides sp., Stenotrophomonas maltophilia, Candida lipolytica, Cryptococcus albidus and Rhodotorula sp.. Further research to identify extracellular metabolites produced by this organism, using a fermentation method was also carried out using a liquid state fermentation technique. 30 mL Erlenmeyer flasks containing 25 mL of NB/KCN (source of CN-) at 37 °C for 168 hrs, with a volume of (5 mL), extracts from the fermentation being filtered, centrifuged, mixed with chloroform for a liquid-liquid extraction procedure subsequent to a nitrogen-facilitated blow-down technique and reconstitution with 100% analytical grade methanol, for LC/MS-TOF 6230 analysis. The analysis revealed that the isolate was able to produce the mycotoxins/secondary metabolites, Fumonisin B1 (FB1) and Deoxynivalenol (DON). Though the isolate (KT275316) demonstrated the ability to biodegrade cyanide as well as produce mycotoxin, an environmentally benign strategy (green chemistry method) with a potential to biodegrade CN-/NH3/NO3/NO2 for the biodegradation of mycotoxins was evaluated, including the identification of biodegradation by-products post-biodegradation treatment. Thus, plant extracts from Nepenthes mirabilis were found to contain enzymes such as carboxylesterase, β-glucosidase, β-glucoronidase and phosphatidyl inositol phospholipase C (identified using both quantitative and qualitative methods). The plant extracts were used with treated samples from the fermentation and were subjected to biodegradation. Thus, resulting in biodegradation by-products such as Heptadecanone Octadecanamide, Octadecenal for FB1 and Tolmetin for DON, respectively. For future research, it is therefore recommended that plant extracts with similar properties to those observed for N. mirabilis extracts (juice) be sought for application of the proposed method.
21
Muzanila, Yasinta C. "Processing of cassava, residual cyanogens and mycotoxin content tradionally processed cassava products." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263048.
22
Alexandre, Allana Patrícia Santos. "Ozone technology as an alternative for reducing mycotoxin contamination in wheat products." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/11/11141/tde-15052018-132453/.
Анотація:
The objective of this study was to evaluate the reduction on the levels of mycotoxins in wheat products and by-products: deoxynivalenol (DON) in whole wheat flour, wheat bran and the efluent from wet milling of wheat flour, and zearalenone (ZEN) in wheat bran. Firstly, the reduction of DON contamination was studied on whole wheat flour, naturaly contaminated, and considering different moisture levels, as well as in wet milling effluent of wheat flour. Further, the impact of the ozonation process on the rheological properties of the processed flour was evaluated. Secondly, the wheat bran naturally co-contaminated with DON and ZEN was studied, considering the degradation of both mycotoxins and the impact of the ozonation process on the bran phenolic compound content and on the antioxidant capacity. The DON degradation in the whole wheat flour increased with both processing time and moisture content. By changing these process parameters, it was possible to obtain products in accordance with the legal limits of Brazil and the European Union, even starting with concentration 2-4 times higher than the legal limits. However, the rheological properties of the whole wheat flour were affected by the process, probably due to protein modifications. The DON concentration on the wet milling effluent was linearly reduced by the ozonation. In wheat bran naturally contaminated and in its equilibrium moisture, the ozonation reduced both DON and ZEN contamination. The degradation of ZEN was higher and faster than the degradation of DON, which could be explained by their molecular structures. It was also observed that the ozonation process did not negatively affect the phenolic compounds and the antioxidant capacity, which is high desirable from a nutritional point of view. Consequently, this work concludes that the ozonation process was effective in reducing DON and ZEN in different wheat products and efluent. It is noteworthy that the results obtained are promising for future studies and to elucidate the mechanism of action of ozone on mycotoxins and constituents of food.O objetivo deste estudo foi avaliar a redução nos níveis de micotoxinas em produtos e subprodutos de trigo: desoxinivalenol (DON) em farinha de trigo integral, farelo de trigo e efluente de moagem da farinha de trigo e zearalenona (ZEA) em farelo de trigo. No primeiro momento, a redução da contaminação por DON foi estudada em farinha de trigo integral, naturalmente contaminada e considerando diferentes níveis de umidade, bem como no efluente de moagem úmida da farinha. Além disso, o impacto do processo de ozonização nas propriedades reológicas da farinha processada foi avaliado. Em segundo lugar, estudou-se o farelo de trigo naturalmente co-contaminado com DON e ZEA, considerando a degradação de ambas as micotoxinas e o impacto do processo de ozonização no conteúdo do composto fenólico do farelo e na capacidade antioxidante. A degradação de DON na farinha de trigo integral aumentou tanto com o tempo de processamento quanto com o teor de umidade. Ao alterar esses parâmetros de processo, foi possível obter produtos de acordo com os limites legais do Brasil e da União Européia, mesmo com a concentração 2-4 vezes superior aos limites legais. Contudo, as propriedades reológicas da farinha de trigo integral foram afetadas pelo processo, provavelmente devido a modificações de proteínas. A concentração de DON no efluente de moagem úmida foi linearmente reduzida pela ozonização. Em farelo de trigo naturalmente contaminado e em sua umidade de equilíbrio, a ozonização reduziu a contaminação DON e ZEA. A degradação do ZEA foi maior e mais rápida que a degradação do DON, o que poderia ser explicado pelas suas estruturas moleculares. Observou-se também que o processo de ozonização não afetou negativamente os compostos fenólicos e a capacidade antioxidante, o que é altamente desejável do ponto de vista nutricional. Consequentemente, este trabalho conclui que o processo de ozonização foi efetivo na redução de DON e ZEA em diferentes produtos de trigo e efluentes. Vale ressaltar que os resultados obtidos são promissores para futuros estudos e elucidar o mecanismo de ação do ozônio sobre micotoxinas e constituintes dos alimentos.
23
García, Daiana. "Predictive mycology and use of natural antifungals to prevent the mycotoxin food hazard." Doctoral thesis, Universitat de Lleida, 2012. http://hdl.handle.net/10803/93074.
Анотація:
Filamentous moulds may cause spoilage in raw materials, foods and feeds. Some of them synthesize mycotoxins which are a risk for human and animal health. For this reason, from the food safety point of view, only mycotoxins, as chemical hazards, are important. Nevertheless, despite the absence of direct correlation between mould growth and mycotoxins production, the prevention of fungal growth in raw materials and foods leads invariably to the prevention of mycotoxins presence.
Due to the fact that moulds can contaminate foods from raw materials till end products, different strategies could be used at the different steps in the food chain. Preharvest strategies include the use of resistant varieties, crop rotation, soil preparation, optimal irrigation, fertilizer, herbicides, insecticides and chemical and biological agents application. Post-harvest strategies include improved drying and storage conditions, together with the use of natural and chemical agents. Predictive models may be used as a strategy to predict and prevent mycotoxigenjc fungal growth and mycotoxins accumulation.
The present PhD work focused in two main strategies:
a) The use of antifungals of natural origin to prevent from mycotoxigenic fungi and mycotoxins
Equisetum arvense and Stevia rebaudiana extracts were analized as possible natural agents to inhibit growth and mycotoxin accumulation in in vitro and in vivo experiments. Both extracts were effective against mycotoxigenic moulds and the mycotoxigenic Aspergillus and Fusarium isolates studied were completely inhibited by a 3% of E. arvense. However, the effect decreased in the in vivo test. In the last case, Equisetum was effective against Aspergillus section Flavi and Fusarium section Liseola growth at high water activity levels and with high infection levels, but mycotoxins levels were not significantly affected.
b) The assessment of the usefulness of predictive models to manage the mycotoxin problem
In an initial experiment, four particular points which deserved in depth study to assess the viability of predictive microbiology in the moulds field were identified: 1) models should be developed for longer time periods; 2) food and raw materials prone to mycotoxin contamination are usually stored under marginal conditions for mould growth, thus performance of models should be checked under such conditions; 3) the impact of the inoculum size in the performance of the models; and 4) the impact of the potential intraspecies variability among isolates in prediction performance.
Prediction of time to growth by kinetic models was clearly linked to inoculum size. On the other hand, the performance of predictive models may be compromised under marginal conditions for fungal growth, the higher variability of results under these conditions results in the need for a higher number of replicates required, specifically for kinetic models. For last, a high intraspecific variability on growth and mycotoxin levels has proven to be wider for the both isolates studies: A. carbonarius and P. expansum. For this reason, a greater number of strains should be included to develop models under non optimal condition for both, growth and for mycotoxin production. A matrix was built from which the number of strains and replicates to be planned for new experiments can be assessed for a reliable estimation of growth parameters and we conclude that increasing the number of strains in an experiment increases the explained variability much more than including further replicates.
Finally, a first attempt was done to model aflatoxins production as a function of growth parameters and time. Aflatoxins accumulation was shown to be better correlated to colony area than either colony diameter or fungal biomass. Luedeking-Piret model was used for this purpose, and reasonable percentages of variability were explained.
To conclude, probability models applied either to mould growth or mycotoxin production might be a valuable tool in food safety management through the food chain.
24
Wilson, Nina Marie. "Strategies to detoxify the mycotoxin deoxynivalenol and improve food safety in the U.S." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/77928.
Анотація:
Mycotoxins are toxic secondary metabolites produced by fungi that are a threat to the health of humans and domestic animals. The most important mycotoxin in the U.S. is deoxynivalenol (DON), which causes symptoms such as vomiting, feed refusal, and weight loss in farm animals. The fungus Fusarium graminearum produces DON in staple crops such as wheat, barley, and corn. It is estimated that the economic losses associated with DON contamination alone exceed $650 million per year in the U.S. New strategies are needed to mitigate DON and improve food safety in the U.S. The overall goal of my research is to discover and employ microorganisms and enzymes to detoxify DON. The specific objectives are to: (1) discover and characterize microorganisms that detoxify DON, (2) use a cell free protein synthesis (CFPS) system to study enzymes that modify DON, (3) engineer yeast to detoxify DON with a metabolic engineering strategy, and (4) deliver a high school unit to teach high school students about mycotoxins in food. In Objective 1, two mixed cultures were identified from environmental samples that converted DON into the less toxic 3-keto-deoxynivalenol (3-keto-DON). In Objective 2, a CFPS system was used to express three known acetyltransferase genes to convert DON to 3-acetyl-DON (3-A-DON). In Objective 3, we identified a potential DON transporter from a library of randomly amplified fragments from the genomes of mixed cultures of microbes isolated from the environment. In Objective 4, we developed and delivered a unique high school unit to educate high school students about potential mycotoxins in food and feed products. The work presented here represents new and improved methods for mitigating mycotoxin contamination in the United States.Ph. D.
25
Alkadri, Dima <1979>. "Fusarium species responsible for mycotoxin production in wheat crop: involvement in food safety." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4884/1/Alkadri_Dima_tesi.pdf.
Анотація:
Fusarium Head Blight (FHB) is a worldwide cereal disease responsible of significant yield reduction, inferior grain quality, and mycotoxin accumulation. Fusarium graminearum and F. culmorum are the prevalent causal agents. FHB has been endemic in Italy since 1995, while there are no records about its presence in Syria. Forty-eight and forty-six wheat kernel samples were collected from different localities and analyzed for fungal presence and mycotoxin contamination. Fusarium strains were identified morphologically but the molecular confirmation was performed only for some species. Further differentiation of the chemotypes for trichothecene synthesis by F. graminearum and F. culmorum strains was conducted by PCR assays. Fusarium spp. were present in 62.5% of Syrian samples. 3Acetyl-Deoxynivalenol and nivalenol chemotypes were found in F. culmorum whilst all F. graminearum strains belonged to NIV chemotype. Italian samples were infected with Fusarium spp for 67.4%. 15Ac-DON was the prevalent chemotype in F. graminearum, while 3Ac-DON chemotype was detected in F. culmorum. The 60 Syrian Fusarium strains tested for mycotoxin production by HPLC-MS/MS have shown the prevalence of zearalenone while the emerging mycotoxins were almost absent. The analysis of the different Syrian and Italian samples of wheat kernels for their mycotoxin content showed that Syrian kernels were mainly contaminated with storage mycotoxins, aflatoxins and ochratoxin whilst Italian grains with mainly Fusarium mycotoxins. The aggressiveness of several Syrian F. culmorum isolates was estimated using three different assays: floret inoculation in growth chamber, ear inoculation in the field and a validated new Petri-dish test. The study of the behaviour of different Syrian wheat cultivars, grown under different conditions, has revealed that Jory is a FHB Syrian tolerant cultivar. This is the first study in Syria on Fusarium spp. associated to FHB, Fusarium mycotoxin producers and grain quality.
26
Alkadri, Dima <1979>. "Fusarium species responsible for mycotoxin production in wheat crop: involvement in food safety." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4884/.
Анотація:
Fusarium Head Blight (FHB) is a worldwide cereal disease responsible of significant yield reduction, inferior grain quality, and mycotoxin accumulation. Fusarium graminearum and F. culmorum are the prevalent causal agents. FHB has been endemic in Italy since 1995, while there are no records about its presence in Syria. Forty-eight and forty-six wheat kernel samples were collected from different localities and analyzed for fungal presence and mycotoxin contamination. Fusarium strains were identified morphologically but the molecular confirmation was performed only for some species. Further differentiation of the chemotypes for trichothecene synthesis by F. graminearum and F. culmorum strains was conducted by PCR assays. Fusarium spp. were present in 62.5% of Syrian samples. 3Acetyl-Deoxynivalenol and nivalenol chemotypes were found in F. culmorum whilst all F. graminearum strains belonged to NIV chemotype. Italian samples were infected with Fusarium spp for 67.4%. 15Ac-DON was the prevalent chemotype in F. graminearum, while 3Ac-DON chemotype was detected in F. culmorum. The 60 Syrian Fusarium strains tested for mycotoxin production by HPLC-MS/MS have shown the prevalence of zearalenone while the emerging mycotoxins were almost absent. The analysis of the different Syrian and Italian samples of wheat kernels for their mycotoxin content showed that Syrian kernels were mainly contaminated with storage mycotoxins, aflatoxins and ochratoxin whilst Italian grains with mainly Fusarium mycotoxins. The aggressiveness of several Syrian F. culmorum isolates was estimated using three different assays: floret inoculation in growth chamber, ear inoculation in the field and a validated new Petri-dish test. The study of the behaviour of different Syrian wheat cultivars, grown under different conditions, has revealed that Jory is a FHB Syrian tolerant cultivar. This is the first study in Syria on Fusarium spp. associated to FHB, Fusarium mycotoxin producers and grain quality.
27
Repossi, Adele <1987>. "Mycotoxin determination in non conventional matrices: development of mass spectrometry based analytical methods." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8667/1/PhD%20Thesis%20Adele%20Repossi.pdf.
Анотація:
Mycotoxins are low-molecular-weight natural products produced, as secondary metabolites, by
filamentous fungi. These molecules represent a wide chemical group with different toxicity effects in
human and other animals.
These toxins can accidentally occur in food and feed, due to a direct or indirect contamination.
The aim of this work was to develop a method for the first time to quantitatively determine
zearalenone and its metabolites (α-zearalenol, β-zearalenol, α-zearalanol, β-zearalanol, zearalanone) in
bovine and human hair using LC-MS/MS.
Once the method was set-up for bovine hair, it was successfully validated according to Decision
657/2002/CE on three analytes, with satisfying performances. Moreover the applicability of the
method was tested on human hair in a one-day validation with reasonable performances.
This method could be a useful tool to evaluate natural feed contamination or detect illegal use of α-
zearalanol in bovines and to perform a first inventory of the occurrence of these molecules in bovine
and human hair, as biomarkers for zearalenone exposure in future studies.
Another purpose of this work was to make a preliminary screening on mycotoxins contamination
(aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, deoxynivalenol, zearalenone, fumonisin B1,
fumonisin B2, ochratoxin, T-2 toxin and HT-2 toxin) in different pet food types for cats.
This research showed that mycotoxin occurrence in pet food for cats can represent an issue to put
under control. Since pets are fed with the same type of pet food for long periods of their life, the
necessity of evaluating mycotoxin presence in feed is evident.
28
Adak, Goutam Kumar. "The use of microorganisms to assay mycotoxins and the elucidation of their mechanisms of action." Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/847128/.
Анотація:
A method was developed for monitoring the growth of a range of bacteria and fungi in the Bactometer 32 impedimeter. 195 yeast strains, 74 strains of mould and 20 strains of bacteria were screened for sensitivity to 1 mug ml[-1] of T-2 toxin. Growth inhibition was assessed impedimetrically. Twelve bacteria, 20 moulds and 38 yeast strains were tested against roridin A, verrucarin A, deoxynivalenol, and diacetoxyscirpenol each at 1 mum ml[-1] . Deoxynivalenol was found to be only slightly toxic. Roridin A and verrucarin A were markedly more toxic than the others to the fungi, but not to the bacteria. Four microorganisms (Bacillus subtilis, Candida albicans. Hansenula fabianii and Pichia burtonii)were selected for further study. No obvious pattern of response could be discerned for the effects of different carbohydrates on microbial sensitivity to T-2 toxin. The effects of T-2 toxin on B. subtilis and C. albicans were greater if chloroform rather than dichloromethane and methanol (95:5, v/v) was used as the toxin carrying solvent, the reverse was true for H. fabianii and P. burtonii. Dose-response curves were constructed, based on impedimetric responses, and no-effect levels were determined for each species. For B. subtilis the no-effect level was 0.35 mum ml[-1], for C. albicans it was 0.40 mum ml[-1], for H. fabianii it was 0.012 mum ml[-1] and for P. burtonii it was 0.018 mum ml[-1]. H. fabianii was selected for further studies. This strain was found to be auxotrophic for proline. The effect of T-2 toxin and verrucarin A on the uptake of radiolabelled proline in H. fabianii cultures was studied. Dose-response curves were constructed for each toxin. It was found that both toxins reduced proline uptake in a dose dependent manner, the no-effect levels were 0.025 mum ml[-1] for T-2 toxin and 0.0125 mum ml[-1] for verrucarin A.
29
Fandohan, Pascal. "Fusarium infection and mycotoxin contamination in preharvest and stored maize in Benin, West Africa." Thesis, University of Pretoria, 2004. http://hdl.handle.net/2263/24999.
30
Wagacha, Maina John. "Development of Fusarium species differing in mycotoxin production and conidia formation on wheat plants." Göttingen Cuvillier, 2008. http://d-nb.info/992684846/04.
31
Shi, Yuhui. "Mechanisms of N-3 polyunsaturated fatty acid inhibition of mycotoxin deoxynivalenol-induced immune response." Diss., Connect to online resource - MSU authorized users, 2008.
Анотація:
Thesis (Ph.D.)--Michigan State University. Dept. of Food Science and Environmental Toxicology, 2008.Title from PDF t.p. (viewed on July 31, 2009) Includes bibliographic references (p. 160-184). Also issued in print.
32
Khatibi, Piyum. "Reduction of the mycotoxin deoxynivalenol in barley ethanol co-products using trichothecene 3-O-acetyltransferases." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/28361.
Анотація:
The fungal plant pathogen Fusarium graminearum Schwabe (teleomorph Gibberella zeae¬) produces a dangerous trichothecene mycotoxin called deoxynivalenol (DON) and causes a devastating disease of barley (Hordeum vulgare L.) called Fusarium head blight (FHB). Food and feed products derived from barley, such as dried distillers grains with solubles (DDGS), may be contaminated with DON and pose a threat to the health of humans and domestic animals. New methods to mitigate the threat of DON in barley need to be developed and implemented. TRI101 and TRI201 are trichothecene 3-O-acetyltransferases that modify DON and reduce its toxicity. The first objective of this research was to isolate unique TRI101 and TRI201 enzymes that modify DON efficiently. We hypothesized that TRI101/TRI201 enzymes from different species of Fusarium would have varying rates and abilities to modify DON. Using degenerate primers, an internal portion of TRI101 or TRI201 was identified in 54 strains of Fusarium. Full-length sequences of seven TRI101 or TRI201 genes were cloned and expressed in yeast. All seven genes acetylated DON, but at different rates. The second objective of this research was to utilize transformed yeast expressing TRI101 or TRI201 to reduce DON levels in barley mashes and ultimately in DDGS. We hypothesized that DON levels would be reduced in DDGS derived from mashes prepared with transformed yeast. Five different barley genotypes were used to prepare the fermentation mashes and DON levels were reduced in all DDGS samples derived from mashes prepared with transformed yeast. The third objective of this study was to characterize barley genotypes developed at Virginia Tech for resistance to FHB and DON. We hypothesized that significant differences in resistance would be observed among barley genotypes and FHB resistance would be associated with reduced DON accumulation. From 2006 to 2010, FHB resistance was assessed in hulled (22 to 37) and hulless (13 to 32) barley genotypes by measuring incidence and index, and DON resistance was determined by quantifying DON levels in ground grain using gas chromatography-mass spectrometry. Our study showed that FHB and DON resistance is significantly determined by genotype. The final objective of this study was to develop a robust tissue culture system necessary for future development of transformed barley plants with FHB resistance gene(s). We hypothesized that callus production would vary among barley genotypes. In our analysis of 47 Virginia barley genotypes, 76% (36/47) of the genotypes produced callus tissue and there were significant differences in callus size. Our work sets the stage for identifying and characterizing DON detoxification genes in the future. The development of commercial barley lines that do not accumulate DON and that are resistant to FHB will directly impact growers and producers of small grains in the eastern U.S.Ph. D.
33
Niland, Michael John. "Critical studies in carbon electrode materials with applications in the electroanalysis of the mycotoxin citrinin." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1018256.
Анотація:
Guided by increasing legislation, the analysis of food borne toxins, including mycotoxins, seeks to address market related demands for the development of analytical systems to monitor this threat to food security and human health. This Thesis is directed at the assessment of the application of electrochemistry for direct electroanalysis and characterisation of the mycotoxin citrinin (CIT) in aqueous media as well as fundamental investigations of the surface of polished and oxidised glassy carbon electrodes (GCE). This study provides the first known account of CIT detection through electrochemical methods. Although electrochemically active, CIT current responses (Ip) were highly irreproducible at polished GCE with a coefficient of variation (C.V.) of 20.16 %. As stability of Ip across multiple electrode preparations is a key requirement in electroanalysis, investigations were directed at attaining stability in CIT Ip. Achieving stability in CIT Ip was investigated via two approaches, including: accounting for Ip variability between electrode preparations as a result of variable GCE surface conditions as a post-data-acquisition analysis and secondly, removing Ip variability through modification of GCE. Accounting for variability in Ip was investigated through the application of double layer capacitance as an indicator of the activity of an electrode, and in so doing serving as a relative mediator of Ip responses between electrodes. Application of this procedure dropped CIT C.V. to a third of starting value across polished GCE (C.V. = 7.18 %), chemically oxidised GCE (Pi-GCE, C.V = 8.47 %) and functionalised multi-walled carbon nanotube modified GCE (fMWCNT, C.V. = 25.79 %) and was effective with analysis of structurally distinct molecules, 2,4-dimethylaniline (2,4-DMA) and 1,2,4-trihydroxybenzene (Triol). Furthermore, it afforded the ability to determine discreet solution overlapping data sets of Ip. Stabilising Ip through GCE surface modification was achieved by anodic electro-oxidation of GCE and allowed for direct electroanalysis of CIT and subsequent characterisation and analysis of CIT in complex media as it reduced C.V. of CIT Ip to 0.73 %. Fundamental investigations of the electrode surface condition are described such that the source of variability could be identified and the interactions of CIT with the electrode understood. Two surface oxidation techniques were applied in modification of GCE; anodic electro-oxidation (EOx GCE) and chemical oxidation using piranha solution (Pi-GCE), analysis of which has previously not been reported. Fundamental analyses to determine surface morphology and chemistry of Pi-GCE, EOx-GCE and polished GCE were conducted using high resolution scanning electron microscopy (HRSEM), scanning electrochemical microscopy (SECM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR) and via electroanalytical methods. These studies showed that both oxidation procedures introduced a variety of oxide species at GCE surface, and further that the extent of those species was similar with total % O being 27.67 % and 33.47 % at Pi-GCE and EOx-GCE respectively. Although chemically similar, each surface was morphologically distinct. Electrochemical analyses at the surfaces revealed Pi-GCE to behave more similarly to polished GCE than EOx-GCE. As CIT responses were found to be stable at EOx-GCE (C.V. = 0.73 %) as opposed to Pi-GCE (C.V. = 22.87 %), stability of CIT Ip was likely to be as a result of a physical interaction with electrode morphology rather than interaction on a chemical basis. Morphological analyses revealed polished GCE and Pi-GCE to be highly morphologically irregular at the micro-scale. Although comparatively smooth, the surface morphology of EOx-GCE does not account for the stability of Ip. This study thus proposed a theory to describe the mechanism by which the limited conductivity and porosity of EOx-GCE allow for it to provide a relatively stable surface area within the oxide layer, adjacent to the electrode surface, and thus provided a stable platform for electroanalysis. Voltammetric characterization of CIT at EOx-GCE revealed that anodic oxidation in aqueous media involved an uneven number of electrons to protons via an ECE mechanism. This was illustrated to be nt = 2e- accompanied by the transfer of 1H⁺ per molecule oxidised. A proposed reaction scheme for the initial stages of CIT oxidation was suggested to involve both hydroxyl and carboxyl moieties of the CIT molecule. CIT oxidation was shown to arise as a result of a relatively complex mass transport regime which included both adsorptive and diffusive derived Ip₁. The LOD in buffered aqueous media was found to be 16 nM, a highly competitive result in relation to chromatographic techniques. Further application of EOx-GCE in complex media illustrated that CIT associates non-specifically with the components of food samples, primarily proteins. As a result of this, extraction of CIT from such media is mandatory. Liquid-liquid extraction illustrated a recovery in CIT Ip₁ and in so doing provided a means of accurately and sensitively detecting CIT from food samples with an LOD of 20 nM. These responses were corroborated by HPLC analyses on the same extractions and illustrate the applicability of electroanalysis as an analytical technique.
34
Tag, Andrew George. "Characterization of the Tri10 gene from Fusarium sporotrichioides." [College Station, Tex. : Texas A&M University, 2003. http://hdl.handle.net/1969.1/64.
Анотація:
Thesis (Ph.D.)--Texas A&M University, 2003."Major Subject: Plant Pathology" Title from author supplied metadata (record created on Jul. 18, 2005.) Vita. Abstract. Includes bibliographical references.
35
Tsakalou, Maria. "Validation of realtime-PCR of Fusarium avenaceum for detection in wheat." Thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-149027.
Анотація:
Mould is a common contamination in cereals. The growth of mould can stimulate mycotoxins production andsome of which at critical concentrations cause health problems in humans and animals. Fusarium is one of thefungus species that has been found in crops and can cause major problems for farmers such as reduced harvestand economic losses. A group of Fusarium species, Fusarium avenaceum, Fusarium poae and Fusariumtricinctum express a mycotoxin, enniatin. The limited information available today about enniatin-forming fungiis that they grow out on fields of wheat in colder climates. This project aims at developing methods for detection,quantification and identification of known and unknown fungi present in Swedish cereals during 2009-2011. Theproject was carried out using two previously published methods, TMAV and MGB, which both use TaqManprobes with realtime-PCR detection. The methods were evaluated for robustness, efficiency, accuracy, inclusionand exclusion. The results showed that both methods, TMAV and MGB, could be used to detect Fusariumavenaceum. The results for the TMAV method were that it could be used with custom annealing temperatureand chemical concentrations for the best detection. The MGB method can be used to detect Fusarium avenaceumwith Fusarium tricinctum in the same analysis. Both methods can be included in future mapping projects when itis of interest to quantify enniatin producing moulds.
36
Pozzo, Marcelo Dal. "IMPACTO DA AFLATOXINA B1, MONTMORILONITA E β-GLUCANA NA FERMENTAÇÃO RUMINAL In vitro". Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/4358.
Анотація:
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe effects of aflatoxin B1 (AFB1) (1μg/mL) were evaluated and sorbents β-glucans derived from Saccharomyces cerevisae with 65% of active ingredient (β-glu) (1mg/mL) and montmirillonite (MMT) (5mg/mL) under ruminal fermentation. Two in vitro assays were conducted. On the first assay the objectives were to determine the production of short chain fatty acids, the production of ammonia during 24-h in vitro. While on the second assay the production of methane (CH4) and kinetic parameters based on gas production date were determined (GPmax= maxim gas production in t time; Lag= lag phase before gas production commenced; S=gas production rate (h-1)) during 72-h in vitro incubation. In each assay six repetitions were made for the following treatments: CONT: control (without AFB1 or sorbents); AF: AFB1 (1μg/mL); β-glu (1mg/mL); β-glu + AF: (1mg/mL of β-glu + 1μg/mL of AFB1); MMT: (5mg/mL); MMT + AF: (5mg/mL of MMT + 1μg/mL of AFB1). The amount of AGCC produced by the β-glu (67,7 mM) treatment was significantly higher about CONT (57,72 mM) and MMT (53,3 mM). treatments. On the other hand, MMT clay reduced the production of NH3 (9,6 mM) about CONT (11,4 mM), AF (12,6 mM) and β-glu (12,2 mM). The amount of GPmax by the β-glu treatment was 103,4 mL, significantly higher about produced CONT (89,0 mL) e MMT (91,6 mL). There was also higher gas production rate by the β-glu treatment. The montmorilonite raised the lag phase and reduced the CH4 production. The results of this study suggest that AFB1 (1μg/mL) has no toxic effect on ruminal fermentation. Whereas the β-glu impacts the ruminal fermentation by increase the AGCC produced. The montmorilonite can delay the bacterial colonization but does t effect the quantity of AGCC produced.
Foram avaliados os efeitos da aflatoxina B1 (AFB1) (1μg/mL) e os adsorventes β-glucanas devivadas de Saccharomyces cerevisae com 65% de princípio ativo (β-glu) (1mg/mL) e montmorilonita (MMT) (5mg/mL) sobre a fermentação ruminal. Foram conduzidos dois ensaios in vitro, no primeiro ensaio o propósito foi determinar a produção de ácidos graxos de cadeia curta, a produção de amônia em 24h de incubação. Enquanto no segundo ensaio determinou-se a produção de metano (CH4) e os parâmetros da cinética da produção de gases (Vf = volume final de gás (ml) no tempo t; L = tempo de colonização; S = taxa de degradação (h-1)) no período de 72h de incubação. Em cada ensaio seis repetições foram realizadas para os seguintes tratamentos: CONT: controle (sem AFB1 ou adsorventes); AF: AFB1 (1μg/mL); β-glu (1mg/mL); β-glu + AF: (1mg/mL de β-glu + 1μg/mL de AFB1); MMT: (5mg/mL); MMT + AF: (5mg/mL de MMT + 1μg/mL de AFB1). A quantidade produzida de AGCC foi significativamente maior no tratamento β-glu (67,7 mM) em relação aos tratamentos CONT (57,72 mM) e MMT (53,3 mM). A MMT reduziu significativamente a produção de NH3 (9,6 mM) em relação aos tratamentos CONT (11,4 mM), AF (12,6 mM) e β-glu (12,2 mM). O tratamento β-glu produziu maior volume de gás (103, 4 mL) em relação aos tratamentos CONT (89,0 mL) e MMT (91,6 mL). Também o tratamento β-glu teve maior taxa de degradação em relação aos demais tratamentos. A montmorilonita aumentou o tempo de colonização e reduziu a produção de CH4. Os resultados deste estudo sugerem que a AFB1 (1μg/mL) não é tóxica a fermentação ruminal. Enquanto, o uso do β-glu impacta a fermentação ruminal, aumentando a produção de AGCC. O uso de montmorilonita pode retardar a colonização bacteriana no alimento porém, não interfere significativamente na quantidade total de AGCC produzidos.
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Eklöf, Disa. "Survey of mycotoxin producing fungi in goji berries, oil seeds and walnuts on the Swedish market." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-208557.
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Pirgozliev, Stoyan R. "Effect of fungicides on Fusarium ear blight and mycotoxin accumulation in winter wheat (Triticum aestivum L.)." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251407.
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Jarašienė, Rasa. "Mikotoksino deoksinivalenolio toksinio poveikio tyrimas modelinėse sistemose in vivo ir in vitro." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080924_174538-38573.
Анотація:
Mikromicetai yra labai įvairi, gyvybinga, aktyvi, įvairiomis veiklos galiomis pasižyminti mikroorganizmų grupė, gebanti aktyviai sintetinti ir išskirti įvairios cheminės prigimties metabolitus. Toksikologiniu ir cheminiu atžvilgiu tai yra heterogeniška medžiagų grupė, kurią sunku klasifikuoti ir apibūdinti. Mikotoksinai aptinkami tiek gyvulių pašare, tiek ir žmonių maisto produktuose. Jie sukelia įvairius žmogaus bei gyvūnų sveikatos sutrikimus. Toksinis šių junginių aktyvumas siejamas su jų chemine struktūra.
Darbas skirtas mikotoksino deoksinivalenolio toksinio poveikio tyrimui, panaudojant dvi modelines tyrimo sistemas - laboratorinius gyvūnus (in vivo) ir ląstelių kultūras (in vitro). Deoksinivalenolis - dažniausiai Fusarium genties mikromicetų produkuojamas metabolitas, savo struktūroje turintis epoksido grupę, kuri, manoma, ir lemia jo toksiškumą.
Panaudojus laboratorinius gyvūnus (peles), kaip tradicinę toksikologinių tyrimų sistemą in vivo, nustatėme, kad deoksinivalenolis po 14-kos parų kasdienio 15 µg/kg koncentracijos poveikio nesukėlė pastebimų organizmo pakitimų, gyvūnai buvo žvalūs, smalsūs, jų svoris augo. Tačiau po išsamesnių tyrimų buvo registruoti kraujo pakitimai, IgA koncentracijos padidėjimas. Panaudojus kitą modelinę toksinio poveikio tyrimo sitemą - ląstelių analizę kultūroje in vitro - nustatėme, kad labai mažos (5 ir 10 µg/ml) tiriamo mikotoksino koncentracijos sukėlė ląstelių pažeidimus. Šiame darbe deoksinivalenolio toksiškumo tyrimui mes... [toliau žr. visą tekstą]Our study is devoted to the analysis of mycotoxin deoxinyvalenol toxicity and comparison of toxicity tests in the model systems in vivo and in vitro. It is known that mycotoxin-producing mold species grow on a wide range of substrates under a wide range of environmental conditions, they are pharmacologically active mold metabolites characterized by vertebrate toxicity. They fall into several chemically unrelated classes, are produced in a strain-specific way and vary in specificity and potency for their target organisms, organs or cells. We have used two model systems for the analysis of deoxinyvalenol effect. One of them is laboratory animal (mice) study or test system in vivo. It is as a traditional method for the evaluation of the toxic substances. We have found that animal diet containing 15 µg/kg deoxynivalenol during short-term (14 days) repeated toxicity test didn‘t influence noticeably animal health. Such small concentration of tested mycotoxin did not appear to depress animals, they were alive and curious, animal weight didn‘t fall behind control. Howewer, at the end of experiment we have found the decrease of mice blood parameters and dramatic increase of Ig A concentration in blood serum. Another test system used in our study was cell culture or test system in vitro. We have used permanent cell lines and newly established primary tissue culture cell lines, derived from potential mycotoxin-target organs: renal and lung. The results presented in this study describe... [to full text]
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Díaz, Gómez Joana. "High-carotenoid maize as feed and food component: mycotoxin contamination, thermal processing, bioavailability and poultry meat production." Doctoral thesis, Universitat de Lleida, 2017. http://hdl.handle.net/10803/405891.
Анотація:
El panís HC (de l'anglès high-carotenoid) va ser modificat genèticament per acumular alts nivells de carotenoides, utilitzant com a base un panís blanc sud-africà (M37W). Durant tres collites consecutives (2013, 2014 i 2015), es van cultivar el panís HC i la seva línia isogènica (M37W) en un camp experimental a Lleida (Catalunya, nord-est d'Espanya). Fusarium spp. va infectar la majoria de grans de panís d'ambdós tipus, el que va originar que es donés contaminació per fumonisines en les dues varietats de panís en tots els anys d'estudi, tot i que la proporció de grans contaminats va ser substancialment més gran en el panís M37W. El panís collit cada any també va servir com a matèria primera per elaborar pinsos a base de panís i productes derivats del panís. Els pollastres alimentats amb la dieta HC van tenir paràmetres de productivitat i salut similars als pollastres alimentats amb les dietes M37W i comercial (amb pigments), i també van desenvolupar una pigmentació similar als pollastres alimentats amb la dieta comercial (amb pigments). Els carotenoides provitamina A del panís HC van ser biodisponibles, almenys en la mateixa mesura que en els additius sintètics i naturals, i van contribuir als nivells de retinol hepàtic en pollastres. La carn obtinguda a partir de pollastres alimentats amb la dieta HC va tenir una bona qualitat i vida útil sensorial, així com una pigmentació groga-ataronjada de llarga durada. Finalment, els purés elaborats amb panís HC han demostrat no només conservar el contingut inicial de carotenoides, sinó també augmentar-lo a causa de l'extracció de carotenoides de la matriu alimentària.El maíz HC (del inglés high-carotenoid) fue modificado genéticamente para acumular altos niveles de carotenoides, utilizando como base un maíz blanco sudafricano (M37W). Durante tres cosechas consecutivas (2013, 2014 y 2015), se cultivó el maíz HC y su línea isogénica (M37W) en un campo experimental en Lleida (Cataluña, noreste de España). Fusarium spp. infectó la mayoría de granos de maíz de ambos tipos, lo que originó que se diera contaminación por fumonisinas en ambas variedades de maíz en todos los años de estudio, aunque la proporción de granos contaminados fue sustancialmente mayor en el maíz M37W. El maíz cosechado cada año también sirvió como materia prima para elaborar piensos a base de maíz y productos derivados del maíz. Los pollos alimentados con la dieta HC tuvieron parámetros de productividad y salud similares a los pollos alimentados con las dietas M37W y comercial (con pigmentos), y también desarrollaron una pigmentación similar a los pollos alimentados con la dieta comercial (con pigmentos). Los carotenoides provitamina A del maíz HC fueron biodisponibles, al menos en la misma medida que en los aditivos sintéticos y naturales, y contribuyeron a los niveles de retinol hepático en pollos. La carne obtenida de pollos alimentados con la dieta HC tuvo una buena calidad y vida útil sensorial, así como una pigmentación amarilla-anaranjada de larga duración. Por último, los purés elaborados con maíz HC han demostrado no sólo conservar el contenido inicial de carotenoides, sino también aumentarlo debido a la extracción de carotenoides de la matriz alimenticia.
High-carotenoid (HC) maize was genetically engineered to accumulate high levels of carotenoids, using as a basis a South African white maize (M37W). During three consecutive harvest seasons (2013, 2014 and 2015), HC maize and its near isogenic line (M37W) were cultivated in an experimental field in Lleida (Catalonia, Northeastern Spain). Fusarium spp. infected most maize kernels, subsequently, fumonisin contamination was found in both maize varieties in all the years of study, but the proportion of contaminated grains was substantially higher in the M37W maize. Maize grains harvested each year also served as raw material to elaborate maize-based feed and maize-derived products. Chickens fed on the HC diet had similar productivity and health parameters to those fed on the M37W and commercial (plus color additives) diets, and they also developed similar pigmentation to those fed on the commercial (plus color additives) diet. Provitamin A carotenoids from HC maize were bioavailable, at least to the same extent than in synthetic and natural additives, and contributed to liver retinol levels in chickens. Meat obtained from chickens fed on the HC diet had a good quality and sensory shelf life as well as a long-lasting golden pigmentation. Finally, HC maize-based porridges showed not only to preserve the initial carotenoid content, but also to enhance it due to the carotenoid extractability from the food matrix.
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Rodríguez, Blanco María. "Mycotoxin risk in dairy farms: feedstuffs contamination, aflatoxin transference to milk and thermal stability of aflatoxin M1." Doctoral thesis, Universitat de Lleida, 2019. http://hdl.handle.net/10803/667885.
Анотація:
Les micotoxines són metabòlits secundaris tòxics produïts per fongs filaments que poden contaminar una àmplia varietat de productes agrícoles tant en etapes precollita com en etapes postcollita. La gestió de la contaminació per micotoxines durant la cadena de producció de la llet és essencial per evitar la presència d'aflatoxina M1 (AFM1) en la llet com a conseqüència de l'exposició d'animals productors de llet a pinsos contaminats per aflatoxina B1 (AFB1). L'objectiu d'aquesta tesi va ser l'estudi de la contaminació per micotoxines en pinsos i ingredients per a pinsos per a vaques lleteres i la seva transferència a la llet. La presència d'aflatoxines i micotoxines de Fusarium es va avaluar mitjançant l'anàlisi de mostres de ració total barrejada (TMR) i diferents tipus d'ensitjats per a vaques lleteres. Mostres de llet procedents de vaques alimentades amb les mostres de TMR recollides es van analitzar per estimar la transferència de AFB1 en el pinso a AFM1 en la llet. Per saber si el tractament tèrmic afecta el contingut de AFM1 en la llet durant el seu processat, es van provar diferents tractaments tèrmics en llet contaminada natural i artificialment.Las micotoxinas son metabolitos secundarios tóxicos producidos por hongos filamentos que pueden contaminar una amplia variedad de productos agrícolas tanto en etapas precosecha como en etapas poscosecha. La gestión de la contaminación por micotoxinas durante la cadena de producción de la leche es esencial para evitar la presencia de aflatoxina M1 (AFM1) en la leche como consecuencia de la exposición de animales productores de leche a piensos contaminados por aflatoxina B1 (AFB1). El objetivo de esta tesis fue el estudio de la contaminación por micotoxinas en piensos e ingredientes para piensos para vacas lecheras y su transferencia a la leche. La presencia de aflatoxinas y micotoxinas de Fusarium se evaluó mediante el análisis de muestras de ración total mezclada (TMR) y diferentes tipos de ensilados para vacas lecheras. Muestras de leche procedentes de vacas alimentadas con las muestras de TMR recogidas se analizaron para estimar la transferencia de AFB1 en el pienso a AFM1 en la leche. Para saber si el tratamiento térmico afecta al contenido de AFM1 en la leche durante su procesado, se probaron diferentes tratamientos térmicos en leche contaminada natural y artificialmente.
Mycotoxins are toxic secondary metabolites produced by filamentous fungi which can contaminate a wide variety of agricultural commodities either at pre-harvest or post-harvest stages. Through the milk supply chain, the management of mycotoxin contamination is essential in order to avoid the presence of aflatoxin M1 (AFM1) in milk as a consequence of the exposure of lactating animals to aflatoxin B1 (AFB1)-contaminated feed. The aim of this Thesis was to evaluate the mycotoxin contamination of feed and feed ingredients for dairy cows and their transference to milk. The occurrence of aflatoxins and Fusarium mycotoxins was evaluated through the analysis of total mixed ration (TMR) samples and different types of silages for dairy cows. Milk samples collecting from cows fed with the sampled TMR were analysed so as to estimate the transference of AFB1 form feed to AFM1 in milk. In order to know whether heat treatment affect to the AFM1 content in milk during processing, different heat treatments were tested in artificially and naturally contaminated milk.
42
Xu, Yang [Verfasser], Petr [Akademischer Betreuer] Karlovsky, Stefan [Gutachter] Vidal, and Franz [Gutachter] Hadacek. "Interactions between invertebrate and mycotoxin-producing fungi / Yang Xu ; Gutachter: Stefan Vidal, Franz Hadacek ; Betreuer: Petr Karlovsky." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://d-nb.info/1192512057/34.
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Mylona, Kalliopi. "Fusarium species in grains : dry matter losses, mycotoxin contamination and control strategies using ozone and chemical compounds." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7876.
Анотація:
This Project identified the relationships between storage conditions, dry matter losses (DMLs) caused by Fusarium species in cereal grains and mycotoxin contamination and assessed novel control strategies for post-harvest grain management including chemical control and ozone. F. graminearum, F. verticillioides and F. langsethiae were inoculated on wheat, maize and oats and stored under environmental conditions where marginal to optimum spoilage and mycotoxin contamination can occur. DMLs were calculated from the CO2 produced and were significantly correlated with deoxynivalenol (DON), zearalenone (ZEA), fumonisins (FUMs) and T-2 and HT-2 toxins respectively. Mycotoxin levels in wheat and maize exceeded the EU legislative limits with 0.9-1% DMLs. Therefore, CO2 monitoring during storage can indicate the level of contamination in a stored batch. Using CO2 production data at different water activity (aw) and temperature conditions, the environmental regimes at which F. langsethiae can grow and contaminate oats with T-2 and HT-2 toxins were identified for the first time. Five acids were examined in vitro and little effect was observed on Fusarium growth, in the aqueous form, while the effect on mycotoxin production varied. Dissolved in ethanol, adipic, fumaric and ferulic acids inhibited fungal growth and controlled DON and FUMs, but T-2 toxin was stimulated by the ethanol. Two garlic essential oils, propyl-propylthiosulfinate (PTS) and propyl propylthiosulfonate (PTSO) were studied for the first time. In vitro, 200 ppm reduced fungal growth (50-100%) and mycotoxin production by >90%. The efficacy was species-dependent. In naturally contaminated oats of 0.93 aw stored for 20 days, 16 ppm PTSO reduced T-2 and HT-2 toxins by 66% and ochratoxin A (OTA) by 88%, while 200 ppm PTS reduced OTA by 95%. In wheat, 100 ppm PTS reduced DON and ZEA and 300 ppm PTS reduced fumonisins by 40-80%. PTSO:PTS (1:1) at 400 and 600 ppm was very effective against DON and ZEA in wheat of 0.92 aw. Ozone (O3) exposure at 200 ppm for 30 min delayed Fusarium spore germination on media of 0.98 aw and inhibited germination at 0.94 aw. O3 was more effective against fungal spores than mycelium and little effect was observed on growing cultures. In vitro, mycotoxin production after exposure depended on the stage of life of the fungi. O3 reduced fungal populations in grains. Mycotoxin production in wet grains treated with 100-200 ppm O3 for 60 min and stored for up to 30 days was reduced or completely inhibited, depending on the species and the exposure system. Simultaneous drying of the grain due to the O3 passage was observed.
44
Opoku, Joseph. "Stink bug-Fusarium interactions and mitigation of associated mycotoxin contamination of corn in the mid-Atlantic, U.S." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/98539.
Анотація:
Stink bugs, including native brown stink bug (Euschistus servus) and invasive brown marmorated stink bug (Halyomorpha halys), cause damage to a variety of crops including field corn (Zea mays). Frequency and size of stink bug infestations have increased in corn fields in the Mid-Atlantic U.S., and there are growing concerns that these infestations may contribute to reductions in grain quality including increased mycotoxin concentrations. Prior research on native and invasive stink bugs has focused on understanding their biology, the damage they cause, and elucidating effective and economic management strategies. However, few studies examined the potential for stink bugs to facilitate fungal infection and mycotoxin contamination of corn grain. Thus, the objectives of this research were to: 1) assess the relationship between invasive brown marmorated stink bug (H. halys) feeding injuries and fumonisin contamination of field corn in the Mid-Atlantic U.S., 2) determine if stink bugs are a vector for mycotoxigenic Fusarium spp. in corn, and 3) evaluate the efficacy of pesticides for mitigating stink bug feeding injury and associated mycotoxin contamination in field corn. A correlation between H. halys feeding injury and fumonisin concentrations was identified, and the ability of H. halys to increase F. verticillioides infection and fumonisin concentrations in corn was demonstrated in field experiments. Fusarium species including fumonisin-producing F. verticillioides and F. proliferatum were isolated from field-collected stink bugs, and in laboratory experiments, E. servus was able to transmit F. verticillioides to non-infected corn ears after feeding on F. verticillioides-infected corn. In field studies, both fungicide and insecticide reduced stink bug-associated mycotoxin concentrations in corn, but levels of control were inconsistent. Thus, additional tactics that target both the stink bug and Fusarium should be implemented to mitigate risks of mycotoxin contamination in corn.Doctor of Philosophy
Native and invasive stink bugs can severely damage crops including field corn. Frequency and size of stink bug infestations in Mid-Atlantic U.S. corn fields have increased, and there is growing concern that this may contribute to reductions in grain quality. Insect feeding injury is a risk factor for fungal infection and mycotoxin contamination in corn. Mycotoxins are toxic chemicals produced by certain fungi that have detrimental health effects on animals including livestock and humans. The relationship between stink bug feeding injuries and mycotoxin contamination in corn grain is not well understood, and management strategies to minimize the risk of mycotoxin contamination in corn need to be identified. The main goal of this research was to characterize interactions between stink bugs and mycotoxin-producing fungi and identify tactics for controlling both the insect pest and pathogen. Specific objectives were to: 1) assess the relationship between invasive brown marmorated stink bug (H. halys) feeding injuries and fumonisin contamination of field corn in the Mid-Atlantic U.S., 2) determine if stink bugs are a vector for mycotoxin-producing Fusarium spp. in corn, and 3) evaluate the efficacy of pesticides for mitigating stink bug feeding injury and associated mycotoxin contamination in field corn. Results from this work indicated that stink bugs have the ability to cause feeding injuries which facilitate invasion of mycotoxin-producing Fusarium species, leading to increases in mycotoxin concentrations in corn grain. Studies also demonstrated that stink bugs can vector Fusarium species during feeding and increase Fusarium infection of corn resulting in subsequent mycotoxin contamination. Field studies indicated that pesticide applications targeting both the stink bugs and mycotoxigenic fungi may be needed to minimize risk of mycotoxin contamination in corn. However, under low pest pressure, application of pesticides is unlikely to be profitable.
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Pearson, Susan M. "Studies on microbiological hazards associated with ethnic foods, with particular reference to mycotoxin formation and clostridium perfringens." Thesis, Glasgow Caledonian University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325965.
46
Cumagun, Christian Joseph R. "Molecular and phenotypic analyses of pathogenicity, aggressiveness, mycotoxin production, and colonization in the wheat-Gibberella zeae pathosystem." [S.l. : s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11163838.
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Cumagun, Christian Joseph R. "Molecular and phenotypic analyses of pathogenicity, aggressiveness, mycotoxin production, and colonization in the wheat-Gebberella zeae pathosystem." Beuren : Verlag Grauer, 2004. http://opus-ho.uni-stuttgart.de/hop/volltexte/2004/56/pdf/Thesis-rev.pdf.
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Camou, Arriola Juan Pedro. "REDUCTION OF AFLATOXIN AND MUTAGENICITY OF NATURALLY-CONTAMINATED CORN DURING PREPARATION OF A CORN SNACK (ASPERGILUS, MYCOTOXIN)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275380.
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Axelsson, Viktoria. "Evaluation of neurotoxic properties of gliotoxin." Doctoral thesis, Stockholm : Department of Neurochemistry, Stockholm university, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1312.
50
Frobose, Hyatt Lowell. "Stimulating estrus and ovulation in lactating sows and consequences for pig growth." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32670.
Анотація:
Doctor of PhilosophyDepartment of Animal Sciences and Industry
Duane L. Davis
Jim L. Nelssen
A total of 188 sows and their litters were used in 2 experiments to evaluate methods to induce estrus and ovulation in lactating sows and effects on pig growth. In Exp. 1, an altered suckling method (ALT) was designed to combine split-weaning and intermittent suckling as a means to reduce the suckling stimulus in primi- and multiparous sows during the last week of lactation (d 18 to 25). The ALT sows were also removed for daily boar exposure. The ALT treatment produced lactational estrus in 75% and 95% of primiparous and multiparous sows, respectively. The ALT sows were in estrus earlier (P < 0.01) than controls post-farrowing, with no effect on subsequent reproductive performance. From d 18 to 32, the ALT treatment benefited (P < 0.01) growth of lightweight pigs but decreased (P < 0.01) BW gain of heavyweight pigs, resulting in overall similar growth. However, variation in BW was reduced (P < 0.01) by 50% for ALT litters. In Exp. 2, varying suckling reduction strategies were applied to boar-exposed lactating sows. Overall, 76% of sows in suckling reduction treatments expressed estrus in lactation. Split-weaned and ALT sows performed reproductively similar to controls, whereas sows with daily litter separation or a single 24 h litter removal tended (P < 0.10) to have reduced conception rates versus controls or split-weaned sows. Reduced suckling treatments differed in their ability to induce lactational estrus and impact on pig BW gain immediately post-weaning. However, no evidence was found of benefit for pig growth to market weight or litter BW variation. Four additional experiments using 902 nursery pigs were conducted to test the efficacy of potential detoxifying agents against deoxynivalenol (DON) in swine diets. The effects of DON were not offset by adding an algae-modified montmorillonite clay nor by a proprietary blend of preservatives and clays. However, hydrothermally treating DON-contaminated diets with sodium metabisulfite modified the structure of DON to a non-toxic DON-sulfonate adduct and restored nursery pig growth via improved (P < 0.05) ADG, ADFI and G:F.