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Detection of mutagens produced by fungi with the Salmonella typhimurium assay
Abstract:
Forty-one fungal isolates (one isolate per species) representing common plant pathogens and food crop contaminants were grown on sterile, polished rice and assayed for mutagenic activity in the Salmonella typhimurium-microsome system. Initially, single doses of aqueous and chloroform extracts of the moldy rice were assayed against the TA100 tester strain by incorporating extracts into the growth medium and by applying small quantities on disks placed on the agar surface. Suspected activity was examined further by analysis of several doses in the plate incorporation assay. Extracts of two aflatoxin-producing isolates (Aspergillus flavus and A. parasiticus) showed pronounced mutagenic activity, as did extracts of five other isolates (A. heterothallicus, A. nidulans, A. terricola, Alternaria tenuis, and Fusarium moniliforme) which did not contain detectable aflatoxins. Seven additional isolates (Botrytis cineria, Ceratocystis fimbriata, Cladosporium herbarum, Fusarium solani f. sp. pisi, Penicillium oxalicum, Thermomyces lanuginosus, and Verticilium albo-atrum) revealed activity which was possibly mutagenic; i.e., mutagenic responses were not observed in both the disk and incorporation assays, and clear dose-related activity was not observed in the incorporation assay. Extracts of the remaining fungi were not mutagenic in the bacterial assay.
Insights
Certain fungi, including common plant pathogens and food contaminants, exhibit mutagenic activity. This study screened 41 fungal isolates for mutagenicity using the Salmonella typhimurium-microsome assay, identifying several potent mutagens.
Area of Science:
- Mycology
- Microbiology
- Toxicology
Background:
- Fungal contamination of food crops is a significant concern.
- Some fungi produce mycotoxins with mutagenic potential.
- Assessing mutagenicity of diverse fungal species is crucial for food safety.
Purpose of the Study:
- To evaluate the mutagenic activity of 41 fungal isolates.
- To identify fungal species that pose a mutagenic risk.
- To investigate mutagenicity in both aflatoxin-producing and non-aflatoxin-producing fungi.
Main Methods:
- Fungal isolates were cultured on sterile rice.
- Aqueous and chloroform extracts were prepared.
- Mutagenicity was assessed using the Salmonella typhimurium-microsome assay (TA100 strain) with plate incorporation and disk diffusion methods.
Main Results:
- Extracts from Aspergillus flavus and A. parasiticus (aflatoxin producers) showed significant mutagenic activity.
- Five non-aflatoxin-producing isolates (A. heterothallicus, A. nidulans, A. terricola, Alternaria tenuis, Fusarium moniliforme) also exhibited pronounced mutagenicity.
- Seven isolates displayed possibly mutagenic activity, requiring further investigation.
Conclusions:
- Several common fungal contaminants and plant pathogens possess mutagenic properties.
- Mutagenicity is not solely linked to aflatoxin production.
- The study highlights potential risks associated with specific fungal species in food and agriculture.