Espécies de Aspergillus produtoras de aflatoxina, na região Araraquarense, SP

Fonseca, Homero; Filho, Alcides Martinelli; Nery, Humberto Del; Roncatto, Elisabeth

doi:10.1590/s0071-12761974000100042

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…The key action for preventing mycotoxins is to block the growth of toxigenic fungi (Fonseca et al 1974, Bennett & Keller 1997. But this is not an easy task, since these microorganisms are widely spread through several ecosystems, covering vast geographical areas.…”

Section: Aspergillus Flavus Is a Very Important Toxigenic Fungus Thatmentioning

confidence: 99%

“…The economic losses due to fungal contamination and the high costs of control measures are enormous (Bennett & Keller 1997) and add up to billions of dollars worldwide (Pozzi 2000). For this reason, efforts on scientific research have been towards prevention rather than remedial action (Bennett & Keller 1997).The key action for preventing mycotoxins is to block the growth of toxigenic fungi (Fonseca et al 1974, Bennett & Keller 1997. But this is not an easy task, since these microorganisms are widely spread through several ecosystems, covering vast geographical areas.…”

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Genetic diversity of environmental Aspergillus flavus strains in the state of São Paulo, Brazil by random amplified polymorphic DNA

Lourenço¹,

Durigon²,

Zanotto³

et al. 2007

Mem. Inst. Oswaldo Cruz

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Aspergillus flavus is a very important toxigenic fungus that produces aflatoxins, a group of extremely toxic substances to man and animals. Toxigenic fungi can grow in feed cropsAflatoxins constitute a group of low molecular weight compounds known to be extremely toxic to animals and man (Bennett & Klich 2003). They are secondary metabolites produced mainly by Aspergillus flavus and A. parasiticus, which are ubiquitous and cosmopolitan fungi able to grow on a wide variety of substrates. However, not all members of each species are toxigenic (Thapar 1988) and, even within potentially toxigenic strains, growth is not necessarily accompanied by toxin production, which depends on favorable environmental conditions such as temperature and humidity (Correa 2000). The economic losses due to fungal contamination and the high costs of control measures are enormous (Bennett & Keller 1997) and add up to billions of dollars worldwide (Pozzi 2000). For this reason, efforts on scientific research have been towards prevention rather than remedial action (Bennett & Keller 1997).The key action for preventing mycotoxins is to block the growth of toxigenic fungi (Fonseca et al. 1974, Bennett & Keller 1997. But this is not an easy task, since these microorganisms are widely spread through several ecosystems, covering vast geographical areas. Furthermore, they can be easily disseminated by wind and may contaminate food crops at different stages, including harvest, post-harvest, processing, transportation, and even at storage conditions in supermarkets.Several approaches can be adopted to prevent or minimize food contamination by aflatoxins, such as controlling potential toxigenic-fungi carriers (e.g., insects and rodents), reducing the storage period and controlling humidity and temperature (Correa 2000). The use of antifungal compounds and insecticides, in turn, has been increasingly criticized from the standpoint of environmental concerns, as well as being costly. The production of resistant-plant varieties, although not having yielded strong positive results, is considered to be a promising alternative (Trail et al. 1995) to prevent both A. flavus substrate colonization and aflatoxin production upon fungal proliferation. However, it is important to bear in mind that the host-parasite co-evolution frequently leads to an "arms race" (Ridley 2001), and it is thus unlikely that fungi remain stable with respect to their invasive or toxigenic potential, as they continuously adapt.The use of non-toxigenic strains for the biological control of toxigenic ones has already been suggested by Egel and collaborators (1994). The non-toxigenic varieties would be artificially disseminated in nature (Egel et al. 1994, Trail et al. 1995 to compete with the toxigenic strains, driving them out of their ecological niches (Trail et al. 1995). In experiments with plants artificially infected with non-toxigenic fugal strains, a reduction by up to 90% in the aflatoxin contamination was observed (Cotty 1989 apud Tran-Dinh et al. 1999). Yet promising, this ...

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Section: Aspergillus Flavus Is a Very Important Toxigenic Fungus Thatmentioning

confidence: 99%

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confidence: 99%

Genetic diversity of environmental Aspergillus flavus strains in the state of São Paulo, Brazil by random amplified polymorphic DNA

Lourenço¹,

Durigon²,

Zanotto³

et al. 2007

Mem. Inst. Oswaldo Cruz

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Variabilidade genética de cepas de Aspergillus flavus isoladas de amendoim.

Reis¹

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O trabalho objetivou construir um dendograma filogenético das cepas de Aspergillus flavus isoladas de amendoim recém-colhido de quatro regiões de São Paulo (Cafelândia, Jaboticabal, Rosália e Tupã), avaliar o potencial toxigênico e agrupar as cepas quanto à produção de esclerócios. A técnica de AFLP foi utilizada para caracterização genotípica. O potencial aflatoxigênico foi avaliado pelo cultivo das cepas em meio de ágar coco, extração das aflatoxinas por clorofórmio, separação por CCD e quantificação por espectrodenditômetro CS-9000. A indução da produção de esclerócios foi feita pela incubação dos isolados em meio ágar Czapeck-DOX. AFLP gerou 78 fragmentos de 27 pb a 365 pb, sendo 13% não polimórficos. O perfil genotípico revelou 31 haplótipos e de 12 grupos no dendograma. A similaridade entre os isolados variou de 37 a 90 %. O potencial aflatoxigênico revelou 91,7 % de cepas produtoras, com níveis entre 39,27 µg/Kg e 28689,61 µg/Kg para AFB1 e 1,50 µg/Kg a 9781,09 µg/Kg para AFB2. Quanto aos esclerócios, 83,9% das cepas foram produtoras, sendo todas tipo S.

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Variabilidade de produção de aflatoxinas por linhagens de Aspergillus flavus em diferentes tempos de manutenção

Taniwaki

Fonseca

Pizzirani-Kleiner

1993

Sci. agric. (Piracicaba, Braz.)

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A.A. PIZZIRANI-KLEINER Prof. do Dep. de Genética da ESALQ/USP -Caixa Postal 9 -CEP: 13418-900-Piracicaba,SP.RESUMO: O presente trabalho fui realizado com a finalidade de se estudar a produção de aflatoxinas por linhagens de A. flavus, recém isoladas, em diferentes tempos de manutenção, a fim de contribuir para um melhor entendimento do mecanismo de variação na produção de aflatoxinas. Para isso, foram utilizadas três linhagens de A. flavus produtoras de aflatoxinas, classificadas como: a) grande produtora; b) média produtora e c) baixa produtora. Neste experimento, que se estendeu por 280 dias, os fungos foram estudados em dois métodos de preservação: mantido em óleo mineral, no meio Czapeck, e repicado periodicamente em meio Czapeck modificado. A analise da produção de aflatoxinas foi efetuada de 30 em 30 dias. A quantificação da toxina foi feita por cromatografía em camada delgada, pela técnica de avaliação visual, de diluição até extinção. Foi constatada uma variação na produção de toxina em todas as linhagens, contudo elas não perderam suas características originais. Descritores: Aflatoxinas, Aspergillus flavus, tempo de manutenção. AFLATOXIN PRODUCTION VARIABILITY BY Aspergillus flavus STRAINS AFTER DIFFERENT STORAGE TIMESABSTRACT: Aflatoxin production by strains recently isolated of Aspergillus flavus was studied, after different storage times understand the mechanisms of possible variations in aflatoxin production. Three A. flavus aflatoxin producing strains were utilized, classified as: a) high producer; b) medium producer and c) low producer. The experiment lasted 280 days and the moulds were studied by two preservation methods: oil covered slants on Czapeck's medium and periodic transfer on Czapeck's modified medium. Quantification of the aflatoxin produced was made at 30 day intervals, on thin-layer chromatography and visual determination by the dilution-to-extinction technique. The production of aflatoxin by all strains varied but they did not lose their initial characteristics. Microscopic examinations revealed thickened zones and hifal enlargements over some globous structures that may be related to aflatoxin production sites. Key Words: Aflatoxins, Aspergillus flavus, storage time. INTRODUÇÃOAflatoxinas são metabólitos secundários do Aspergillus flavus, responsáveis por intoxicações e têm se mostrado cancerígenas a diversas especies de animais (BUTLER, 1974 e WOGAN, 1966. Devido a essa característica, o estudo das aflatoxinas tem sido alvo de atenção nunca devotada a nenhum outro problema relacionado a fungos (CHRISTENSEN, 1975). Uma série de aflatoxinas são produzidas por A. flavus e linhagens relacionadas, destacando-se B l e B 2 , G 1 e G 2 , que apresentam fluorescência azul violeta e esverdeada, respectivamente, quando analisadas por cromatografia em camada delgada e utilizando luz ultravioleta em 365 nm e estão entre as micotoxinas mais potentes.Varios gêneros e especies de fungos já foram relatados como produtores de aflatoxinas, porém, atualmente, pode-se dizer que os grandes produtores pe...

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Espécies de Aspergillus produtoras de aflatoxina, na região Araraquarense, SP

Cited by 3 publications

References 17 publications

Genetic diversity of environmental Aspergillus flavus strains in the state of São Paulo, Brazil by random amplified polymorphic DNA

Genetic diversity of environmental Aspergillus flavus strains in the state of São Paulo, Brazil by random amplified polymorphic DNA

Variabilidade genética de cepas de Aspergillus flavus isoladas de amendoim.

Variabilidade de produção de aflatoxinas por linhagens de Aspergillus flavus em diferentes tempos de manutenção

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