Academic literature on the topic 'Aflatoxigenic fungi'

The dichlorvos-ammonia (DV-AM) method is a simple but sensitive visual method for detecting aflatoxigenic fungi. Here we sought to develop a selective medium that is appropriate for the growth of aflatoxigenic fungi among soil mycoflora. We examined the effects of different concentrations of carbon sources (sucrose and glucose) and detergents (deoxycholate (DOC), Triton X-100, and Tween 80) on microorganisms in soils, using agar medium supplemented with chloramphenicol. The results demonstrated that 5–10% sucrose concentrations and 0.1–0.15% DOC concentrations were appropriate for the selective detection of aflatoxigenic fungi in soil. We also identified the optimal constituents of the medium on which the normal rapid growth of Rhizopus sp. was completely inhibited. By using the new medium along with the DV-AM method, we succeeded in the isolation of aflatoxigenic fungi from non-agricultural fields in Fukui city, Japan. The fungi were identified as Aspergillus nomius based on their calmodulin gene sequences. These results indicate that the new medium will be useful in practice for the detection of aflatoxigenic fungi in soil samples including those from non-agricultural environments.

The ability of larvae of the lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), to augment contamination of peanut pods with aflatoxigenic fungi, Aspergillus flavus Link and A. parasiticus Speare (A. flavus-type fungi), was investigated in laboratory and field studies. Aflatoxigenic fungi were found in or on frass from 28.6% of field-collected larvae and in 8.9% of sterilized and macerated larvae. More aflatoxigenic fungi tended to be found in pods from untreated plots than in plots treated with chlorpyrifos in field trials. Contamination of pods or seeds with A. flavus-type fungi was positively correlated in all four trials with scarification of pods, and this relationship has been quantified. Since appropriate insecticide treatments can decrease populations of lesser cornstalk borers, which would decrease pod scarification, these same treatments may decrease contamination with aflatoxigenic fungi. Treatment thresholds for the lesser cornstalk borer need to be reconsidered based upon this information.

Aflatoxin contamination of nuts is an increasing concern to the consumer’s health. Portugal is a big producer of almonds, but there is no scientific knowledge on the safety of those nuts, in terms of mycotoxins. The aim of this paper was to study the incidence of aflatoxigenic fungi and aflatoxin contamination of 21 samples of Portuguese almonds, and its evolution throughout the various stages of production. All fungi belonging toAspergillussectionFlaviwere identified and tested for their aflatoxigenic ability. Almond samples were tested for aflatoxin contamination by HPLC-fluorescence. In total, 352 fungi belonging toAspergillussectionFlaviwere isolated from Portuguese almonds: 127 were identified asA. flavus(of which 28% produced aflatoxins B), 196 as typical or atypicalA. parasiticus(all producing aflatoxins B and G), and 29 asA. tamarii(all nonaflatoxigenic). Aflatoxins were detected in only one sample at 4.97 μg/kg.

Desiccated coconut agar is the conventional medium used for the detection of aflatoxigenic fungi and direct visual determination of aflatoxins. In this study, an improved medium was developed by the incorporation of 0.2% (v/v) neutral red dye into desiccated coconut agar. The medium was formulated by a 2×3 factorial design of neutral red and phenol red stains at three concentration levels. The formulated medium was evaluated for performance by screening for the minimal time required by each Aspergillus species to produce pigments and fluorescence of agar. The medium was also employed for detection of aflatoxigenic fungi and direct visual determination of aflatoxins in foods and fish-meal. The neutral red desiccated coconut agar (NRDCA) as compared to the conventional desiccated coconut agar (DCA) had a light pink background as opposed to the white background of the DCA which often interferes with the visibility of fluorescence. The time of pigmentation and fluorescence production on NRDCA was 28 and 38 h respectively as compared with 33 and 44 h of DCA and 41 and 48 h of palm kernel agar (PKA: an alternative culture medium for cultivation of aflatoxigenic fungi with a reddish pink background). Furthermore, aflatoxigenic moulds were detected in all food commodities and fish-meal after 60 hours of incubation. The highest percentage of aflatoxigenic moulds (62.5%) was detected in yam flour with NRDCA while the lowest percentage (4.46%) was detected with PKA on rice. In addition, aflatoxins were produced in high amounts in food commodities in which aflatoxigenic moulds were detected and there was a significant positive correlation (r=0.4, P<0.05) between the isolates and aflatoxin concentration of the food samples. Rice (a major staple food for Nigerians) had the highest total aflatoxin concentration of 140, 220 and 205 µg/kg on DCA, NRDCA and PKA respectively, while ‘gari’ had the least concentration of 45, 50 and 40 µg/kg. These values were far above the NAFDAC recommended level of 10 µg/kg for unprocessed foods in Nigeria and therefore a source of concern. In addition the study also reveals that Aspergillus nomius can produce aflatoxins B1 in copious amounts on NRDCA, contrary to previous reports of its production in minute quantities on laboratory media. The benefit of this study lies in the rapid analysis and simplified technique for the detection of aflatoxigenic fungi and visual determination of aflatoxins.

Abstract 
 The present study was designed to investigate the mycological contamination and aflatoxigenic potential of fungi isolated from the indigenous certified varieties of wheat. Surface spread method was used to determine mycological contamination whereas to determine the toxigenic potential of isolated fungi and screening of wheat grains for aflatoxin contamination thin layer chromatography was used. All the collected samples revealed fungal contamination however none of the fungal isolate showed aflatoxigenic potential. Similarly all the samples showed negativity for aflatoxin. It can be concluded that for human public health, cereal grains must be subjected to quality control and mycotoxicologicalexaminations.

Aflatoxin contamination has been causing great concern worldwide due to the major economic impact on crop production and their toxicological effects to human and animals. Contamination can occur in the field, during transportation, and also in storage. Post-harvest contamination usually derives from the pre-harvest infection of aflatoxigenic molds, especially aflatoxin-producing Aspergilli such as Aspergillus flavus and A. parasiticus. Many strategies preventing aflatoxigenic molds from entering food and feed chains have been reported, among which biological control is becoming one of the most praised strategies. The objective of this article is to review the biocontrol strategy for inhibiting the growth of and aflatoxin production by aflatoxigenic fungi. This review focuses on comparing inhibitory behaviors of different antagonistic microorganisms including various bacteria, fungi and yeasts. We also reviewed the bioactive compounds produced by microorganisms and the mechanisms leading to inhibition. The key factors influencing antifungal activities of antagonists are also discussed in this review.

碩士<br>國立成功大學<br>太空與電漿科學研究所<br>103<br>This experiment tests the ability of atmospheric pressure non-thermal plasma treatments in the prevention of aflatoxigenic fungi infection. There are charged particles, electric field, radicals and UV light inside plasmas and these elements might trigger different physical or chemical effects during non-thermal plasma treatments. In this experiment, the experimental samples received indirect plasma treatments with different time duration and gas compositions which mean only the remote effects caused by plasma treatments could be seen. In this work, plasmas were produced by dielectric barrier discharge method. The operation gases were air and a mixed gas of 97% He and 3% O2. After plasma treatments, fungi growth rate was observed by taking pictures and the existence of aflatoxin was qualitatively detected by black light method. The final results show that the radicals in both He/O2 and air plasma might facilitate fungi growth rate which means peanuts received indirect plasma treatments grew fungi faster than control group. The outcomes of aflatoxin detection also show that the fungi grown on all the sample are aflatoxigenic fungi.

Aflatoxin (AF) contamination of nuts is an increasing concern to the consumer’s health. Portugal is a big producer of almonds and chestnuts, but there is no scientific knowledge on the safety of those nuts. AFs B1, B2, G1 and G2 are produced mainly by some species of Aspergillus belonging to section Flavi, which is composed of a large number of very closely related species. While these species are difficult to differentiate morphologically and even genetically, they differ in a characteristic that is of paramount importance for food safety, as only some are responsible for the production of the highly toxigenic AFs. Taxonomy and species identification are therefore subject of great interest, and the establishment of schemes for species and for aflatoxigenic strains identification that are simultaneously accurate, sensitive, robust and expedite is mandatory. This work had three major goals: the first was to provide knowledge on the general mycobiota, aflatoxigenic fungi and AF contamination of Portuguese almonds and chestnuts, and its evolution throughout the various stages of production (field, storage and processing). For this matter, 45 chestnut samples were collected from orchards from Trás-os-Montes. Forty-seven almond samples were collected in Trás-os-Montes at different stages of production: field, storage and processing. All fungi belonging to genus Aspergillus were isolated and identified to the section level, and all isolates belonging to section Flavi were further tested for their aflatoxigenic ability. Fungi representative of other genera were identified to the genus level. Almond samples were tested for AF contamination. The mycobiota of almonds and chestnut was found to vary in terms of both matrix and stage of production. Chestnuts were mainly contaminated with the genera Fusarium, Cladosporium, Alternaria and Penicillium, and the genus Aspergillus was only rarely found, whereas almonds were more contaminated with Aspergillus. No Aspergillus section Flavi were isolated from chestnuts. In almonds, Fusarium, Cladosporium, Alternaria and Penicillium decreased from field to the end of processing, whereas Aspergillus increased significantly, including those from section Flavi. In total, 352 fungi belonging to section Flavi were isolated from Portuguese almonds, of which 231 isolates (66%) were aflatoxigenic. Even so, only one sample from storage was found to be contaminated with AFs (4.97 µg/kg) at a level below the maximum levels recently imposed by the Commission Regulation (EU) No 165/2010. The second goal of this work was to characterise and identify the isolates of Aspergillus section Flavi by applying a polyphasic approach including classic phenotypic and molecular methods as well as the innovative technology protein spectral analysis Matrix-Assisted Laser Desorption/Ionisation-Time of Flight Intact-Cell Mass Spectrometry (MALDI-TOF ICMS), and to devise accurate and sensitive schemes for species identification. For the morphological analysis, fungi were cultured on different media and were characterised for several macro and micro morphological features. Morphological analysis was complemented with biochemical analyses, which consisted of determining the extrolite profiles relative to AFs and cyclopiazonic acid. A group of selected isolates was identified molecularly based on the sequencing of the ITS region and partial calmodulin gene. Spectral analysis was made by MALDI-TOF ICMS to obtain spectra of protein masses. Dendrograms of relatedness were obtained for each set of data and used to compare sensitivity and accurateness of the different approaches. From the preliminary morphological analysis, three morphotypes were identified: as “A. flavus morphotype” (36.4% of the isolates), “A. parasiticus morphotype” (55.4%), and “A. tamarii morphotype” (8.2%). The 3 morphotypes were then divided into 9 phenotypes based on their extrolite profile. Genotypic and spectral analyses clustered the selected isolates into the same 3 groups created by morphological analysis. Furthermore, all sets of data, including the morphological complemented with extrolite profile, were able to further resolve the isolates into more restrictive clusters. They all positioned two of the 9 phenotypes in two unidentified terminal clades closely related to A. parasiticus. The third goal was to test a molecular method based on multiplex PCR and RT-PCR for the ability to differentiate aflatoxigenic and non-aflatoxigenic isolates. Two genes of the AF biosynthetic pathway, aflD (= nor1) and aflQ (= ord1= ordA), were tested for presence and expression (by PCR and RT-PCR, respectively). The presence of both genes did not correlate with aflatoxigenicity. In terms of gene expression, aflD was not considered a good marker for differentiating aflatoxigenic from non-aflatoxigenic isolates, but aflQ showed a good correlation between expression and AF-production ability. In conclusion, Portuguese almonds and chestnuts seem to be generally safe in terms of AF contamination. Nevertheless, the majority of the isolates of Aspergillus section Flavi obtained from Portuguese almonds was found to be aflatoxigenic, which may constitute a problem in terms of food safety if storage and processing conditions are not effectively controlled. At present, these conditions seem to be guaranteed, since only one almond sample was found to be contaminated. At the species identification level, good agreement was obtained between the 3 methods of analysis since they all generated similar dendrograms with concordant strain clustering. Morphological analysis has shown sensitive and reliable as a preliminary method for species identification only when complemented with the extrolite profile. The calmodulin gene showed to be more robust and reliable as genomic marker for this group of fungi than the ITS region, providing good DNA barcoding potential. MALDI-TOF ICMS results confirmed that this technique is highly reliable for fungal identification, and is faster and less expensive in terms of labour and consumables when compared with other biological techniques, which is essential whenever there is a paucity of characters for defining many fungal species and when high numbers of isolates are involved. Expression analysis of the aflQ gene seems to be a good method for the differentiation of aflatoxigenic and non-aflatoxigenic isolates.

Tese de doutoramento em Engenharia Química e Biológica<br>Aflatoxin (AF) contamination of nuts is an increasing concern to the consumer’s health. Portugal is a big producer of almonds and chestnuts, but there is no scientific knowledge on the safety of those nuts. AFs B1, B2, G1 and G2 are produced mainly by some species of Aspergillus belonging to section Flavi, which is composed of a large number of very closely related species. While these species are difficult to differentiate morphologically and even genetically, they differ in a characteristic that is of paramount importance for food safety, as only some are responsible for the production of the highly toxigenic AFs. Taxonomy and species identification are therefore subject of great interest, and the establishment of schemes for species and for aflatoxigenic strains identification that are simultaneously accurate, sensitive, robust and expedite is mandatory. This work had three major goals: the first was to provide knowledge on the general mycobiota, aflatoxigenic fungi and AF contamination of Portuguese almonds and chestnuts, and its evolution throughout the various stages of production (field, storage and processing). For this matter, 45 chestnut samples were collected from orchards from Trás-os-Montes. Forty-seven almond samples were collected in Trás-os-Montes at different stages of production: field, storage and processing. All fungi belonging to genus Aspergillus were isolated and identified to the section level, and all isolates belonging to section Flavi were further tested for their aflatoxigenic ability. Fungi representative of other genera were identified to the genus level. Almond samples were tested for AF contamination. The mycobiota of almonds and chestnut was found to vary in terms of both matrix and stage of production. Chestnuts were mainly contaminated with the genera Fusarium, Cladosporium, Alternaria and Penicillium, and the genus Aspergillus was only rarely found, whereas almonds were more contaminated with Aspergillus. No Aspergillus section Flavi were isolated from chestnuts. In almonds, Fusarium, Cladosporium, Alternaria and Penicillium decreased from field to the end of processing, whereas Aspergillus increased significantly, including those from section Flavi. In total, 352 fungi belonging to section Flavi were isolated from Portuguese almonds, of which 231 isolates (66%) were aflatoxigenic. Even so, only one sample from storage was found to be contaminated with AFs (4.97 μg/kg) at a level below the maximum levels recently imposed by the Commission Regulation (EU) No 165/2010. The second goal of this work was to characterise and identify the isolates of Aspergillus section Flavi by applying a polyphasic approach including classic phenotypic and molecular methods as well as the innovative technology protein spectral analysis Matrix-Assisted Laser Desorption/Ionisation-Time of Flight Intact-Cell Mass Spectrometry (MALDI-TOF ICMS), and to devise accurate and sensitive schemes for species identification. For the morphological analysis, fungi were cultured on different media and were characterised for several macro and micro morphological features. Morphological analysis was complemented with biochemical analyses, which consisted of determining the extrolite profiles relative to AFs and cyclopiazonic acid. A group of selected isolates was identified molecularly based on the sequencing of the ITS region and partial calmodulin gene. Spectral analysis was made by MALDI-TOF ICMS to obtain spectra of protein masses. Dendrograms of relatedness were obtained for each set of data and used to compare sensitivity and accurateness of the different approaches. From the preliminary morphological analysis, three morphotypes were identified: as “A. flavus morphotype” (36.4% of the isolates), “A. parasiticus morphotype” (55.4%), and “A. tamarii morphotype” (8.2%). The 3 morphotypes were then divided into 9 phenotypes based on their extrolite profile. Genotypic and spectral analyses clustered the selected isolates into the same 3 groups created by morphological analysis. Furthermore, all sets of data, including the morphological complemented with extrolite profile, were able to further resolve the isolates into more restrictive clusters. They all positioned two of the 9 phenotypes in two unidentified terminal clades closely related to A. parasiticus. The third goal was to test a molecular method based on multiplex PCR and RT-PCR for the ability to differentiate aflatoxigenic and non-aflatoxigenic isolates. Two genes of the AF biosynthetic pathway, aflD (= nor1) and aflQ (= ord1= ordA), were tested for presence and expression (by PCR and RT-PCR, respectively). The presence of both genes did not correlate with aflatoxigenicity. In terms of gene expression, aflD was not considered a good marker for differentiating aflatoxigenic from non-aflatoxigenic isolates, but aflQ showed a good correlation between expression and AFproduction ability. In conclusion, Portuguese almonds and chestnuts seem to be generally safe in terms of AF contamination. Nevertheless, the majority of the isolates of Aspergillus section Flavi obtained from Portuguese almonds was found to be aflatoxigenic, which may constitute a problem in terms of food safety if storage and processing conditions are not effectively controlled. At present, these conditions seem to be guaranteed, since only one almond sample was found to be contaminated. At the species identification level, good agreement was obtained between the 3 methods of analysis since they all generated similar dendrograms with concordant strain clustering. Morphological analysis has shown sensitive and reliable as a preliminary method for species identification only when complemented with the extrolite profile. The calmodulin gene showed to be more robust and reliable as genomic marker for this group of fungi than the ITS region, providing good DNA barcoding potential. MALDI-TOF ICMS results confirmed that this technique is highly reliable for fungal identification, and is faster and less expensive in terms of labour and consumables when compared with other biological techniques, which is essential whenever there is a paucity of characters for defining many fungal species and when high numbers of isolates are involved. Expression analysis of the aflQ gene seems to be a good method for the differentiation of aflatoxigenic and non-aflatoxigenic isolates<br>A contaminação com aflatoxinas (AFs) dos frutos de casca rija é um problema com interesse crescente no que respeita à saúde do consumidor. A castanha e a amêndoa são produtos agrícolas de elevado interesse económico para Portugal, no entanto não existe conhecimento científico quanto à sua segurança em termos de AFs. As AFs B1, B2, G1 e G2 são micotoxinas de elevado grau toxigénico, e são produzidas por algumas espécies de Aspergillus secção Flavi. Esta secção integra um elevado número de espécies muito próximas, tanto ao nível morfológico como molecular, mas que diferem numa característica de elevado interesse para a segurança alimentar - a sua capacidade para produzir AFs. Por esta razão, a taxonomia e identificação de espécies desta secção revestem-se de grande interesse, pelo que o estabelecimento de esquemas de identificação simultaneamente precisos, sensíveis, robustos e expeditos é imperioso. O presente trabalho teve três objectivos principais. O primeiro objectivo foi obter informação sobre a incidência de fungos filamentosos, com particular incidência sobre os fungos produtores de AFs, e sobre a contaminação com AFs das amêndoas e castanhas portuguesas, e sua evolução ao longo das várias fases de produção. Neste sentido, foram analisadas 45 amostras de castanha colhidas em soutos de Trás-os-Montes e 47 amostras de amêndoa de Trás-os-Montes e Algarve colhidas em diferentes fases de produção (campo, armazenamento e processamento). Todos os fungos do género Aspergillus foram isolados e identificados até à secção, e todos os fungos pertencentes à secção Flavi foram identificados até à espécie e caracterizados quanto à sua capacidade aflatoxigénica. Fungos representativos de outros géneros foram identificados apenas até ao género. As amostras de amêndoa foram ainda analisadas quanto à contaminação com AFs. A micobiota das amêndoas e castanhas variou em termos de matriz e de fase de produção. As castanhas mostraram contaminação dominada pelos géneros Fusarium, Cladosporium, Alternaria e Penicillium, sendo o género Aspergillus encontrado com pouca frequência, enquanto nas amêndoas o género Aspergillus foi detectado com elevada incidência. Não foi isolado qualquer fungo da secção Flavi de castanhas. Nas amêndoas, os géneros Fusarium, Cladosporium, Alternaria e Penicillium diminuiram progressivamente desde o campo até ao final do processamento, enquanto a incidência de Aspergillus, incluindo a secção Flavi, aumentou. No total das amostras de amêndoa foram isolados 352 fungos pertencentes à secção Flavi, dos quais 66% eram aflatoxigénicos. No entanto, apenas foi identificada uma amostra contaminada com níveis detectáveis de AFs (4,97 μg/kg), mas inferiores aos níveis máximos impostos pelo Regulamento (CE) Nº 165/2010 da Comissão Europeia. O segundo objectivo do presente trabalho foi caracterizar e identificar os isolamentos de Aspergillus secção Flavi através de uma abordagem polifásica incluindo a caracterização fenotípica clássica e molecular, assim como a inovadora tecnologia de análise espectral de proteínas Matrix- Assisted Laser Desorption/Ionisation-Time of Flight Intact-Cell Mass Spectrometry (MALDI-TOF ICMS), e delinear esquemas robustos e simultaneamente sensíveis de identificação de espécies. A análise macro e micromorfológica em diferentes condições de cultura foi complementada com a análise de extrólitos, nomeadamente AFs e ácido ciclopiazónico (CPA). Um grupo de 24 fungos foi identificado molecularmente pela análise de sequências da região ITS e do gene da calmodulina. A análise espectral por MALDI-TOF ICMS foi aplicada a 69 fungos. Foi construído um dendrograma de similaridade para cada um dos grupos de dados e os resultados foram comparados em termos de precisão, robustez e sensibilidade. Na análise morfológica preliminar foram identificados três morfotipos distintos designados “morfotipo A. flavus” (36,4% dos isolamentos), “morfotipo A. parasiticus” (55,4%), e “morfotipo A. tamarii” (8,2%). Estes morfotipos foram posteriormente divididos em nove fenótipos, com base no seu perfil de extrólitos. As análises genotípica e espectral criaram três grupos (clades) correspondentes aos obtidos na análise morfológica e posicionaram dois dos nove fenótipos em clades terminais relativos a taxa não identificados. O terceiro objectivo deste trabalho foi testar um método baseado em PCR multiplex e RT-PCR para diferenciação de estirpes aflatoxigénicas e não-aflatoxigénicas. Para tal, foram seleccionados dois genes da cadeia biossintética das AFs, aflD (= nor1) e aflQ (= ord1= ordA), para os quais a presença e expressão foram testadas por PCR e RT-PCR, respectivamente. A presença de ambos os genes não se correlacionou com a capacidade aflatoxigénica dos indivíduos testados. Em termos de expressão, apenas o gene aflQ mostrou boa correlação com a produção de AFs, tendo sido considerado um bom marcador molecular da capacidade aflatoxigénica. Em conclusão, as castanhas e amêndoas com origem em Portugal parecem possuir boa qualidade em termos de contaminação com AFs. No entanto, a maioria dos isolamentos de Aspergillus secção Flavi provou ser aflatoxigénica, o que pode constituir um problema de segurança alimentar para as amêndoas, caso as condições de armazenamento e processamento não sejam devidamente controladas. Em termos de identificação de espécies, foi obtido um nível de concordância elevado entre as diferentes abordagens usadas. A análise morfológica mostrou-se um método fiável e sensível para identificação preliminar dos isolamentos apenas se complementada com a análise de extrólitos. O gene da calmodulina mostrou-se mais robusto e sensível do que a região ITS, demonstrando maior potencial como marcador molecular. Os resultados obtidos por MALDI-TOF ICMS confirmaram que esta técnica é altamente fiável na identificação de Aspergillus secção Flavi, tendo como principal vantagem o facto de ser significativamente menos dispendioso, tanto em termos de tempo como de consumíveis, quando comparado com as restantes metodologias. Esta técnica reveste-se de elevada importância nos casos em que estão envolvidos numerosos espécimens com elevada proximidade taxonómica. Relativamente à diferenciação de isolamentos aflatoxigénicos e não-aflatoxigénicos, a análise da expressão do gene aflQ sob condições indutoras da produção de AFs mostrou ser um método fiável.

This study assessed the mycological and aflatoxin contamination of peanuts collected from Kinshasa, DRC and Pretoria, South Africa. Forty peanut samples were collected randomly at informal markets in the two cities and analysed for mycoflora and aflatoxins (B1, B2, G1 and G2) using standard methods. The results indicated that 95% and 100% of peanut samples collected from Kinshasa and Pretoria, respectively were contaminated with aflatoxigenic fungi with Kinshasa’s samples being the most contaminated (up to 49, 000 CFU/g). Seventy percent (70 %) of Kinshasa-samples and 35% of Pretoria-samples exceeded the maximum allowable limit of aflatoxin B1 set by JECFA (5 ppb). Statistical evidence showed a significant positive correlation between mycoflora and aflatoxin level for Kinshasa-samples (r = 0.4743, p < 0.005) while Pretoria-samples showed no correlation. The study reveals that high level of contamination in Kinshasa-samples could be due to the tropical nature of the climate and poor storage conditions as compared to Pretoria which is sub-tropical and sanitary regulations are enforced.<br>Life & Consumer Sciences<br>M. Sc. (Life Sciences)

Mycotoxins, the secondary fungal metabolites are important contaminants of food and feed. Among the other contaminants, aflatoxin B1 (AFB1) and OTA are frequently detected in the animal feed product. In the present study, the mixed dairy cow feed products were collected from the supermarkets in Qatar and analyzed for the presence of AFB1 and OTA. Yeast strains were isolated and tested for their biological control activities against aflatoxigenic and ochratoxin fungi. We demonstrated that local 15 yeasts isolates have important antifungal potential activities through the synthesis of volatile organic compounds (VOC) that are able to act against the mycotoxigenic fungi and their synthesis of the mycotoxins. Two Yeast strains (4&amp;2) isolated from fermented food, have shown a great antifungal inhibition growth in-vitro as well as spores inhibition and mycotoxins synthesis.