Submitted to: Mycotoxin Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/16/2014
Publication Date: 2/7/2014
Publication URL: http://handle.nal.usda.gov/10113/60900
Citation: Hua, S.T., Beck, J.J., Sarreal, S.L., Gee, W.S. 2014. The major volatile compound 2-phenylethanol from the biocontrol yeast Pichia anomala inhibits growth and expression of aflatoxin biosynthetic genes of Aspergillus flavus. Mycotoxin Research. 30(2):71-78. doi: 10.1007/s12550-014-0189-Z. Interpretive Summary: Multiple strategies are being developed to eliminate harmful effects of aflatoxin. A recent review indicates these methods intended for growers or consumers are not practical or partially effective or have an ecological impact. New approaches should be explored for developing safe, practical and cost-effective methods for consumers. Natural volatile compounds from plant and microbial origin have been investigated for their biocontrol effects on fungal growth and aflatoxin production. 2-phenylethanol was shown to inhibit spore germination and aflatoxin production of A. flavus. Epigenetic control in down regulation of aflatoxin biosynthetic genes was elucidated. Future research is needed to determine the specific mechanisms by which aflatoxin production is controlled by epigenetic regulation and the complex network of cellular response to volatiles. It is also important to characterize different patterns of transcripts of HAT and HDAC genes evoked by volatiles. This could create the potential to combine volatiles for effective control of aflatoxin production.
Technical Abstract: Aspergillus flavus is a globally distributed fungus and an important food contaminant because it produces the most potent natural carcinogenic compound known as aflatoxin (AF) B1. The major volatile from a yeast strain, Pichia anomala WRL-076 was identified by SPEM-GC/MS analysis to be 2-phenylethanol. The compound was shown to inhibit spore gemination and aflatoxin production of A. flavus. Fourteen of the genes in aflatoxin biosynthetic pathways including aflR, pksA, nor1 and omtB were down regulated significantly by 2-phenylethanol in the range from several fold to more than 10,000 fold. Epigenetic control was demonstrated for the first time in A. flavus to play a role in down regulation of aflatoxin biosynthetic genes. We detected transcripts of MYST1, MYST2, MYST3, gcn5, and hdaA in A. flavus NRRL3357 grown for 24, 48 and 72 h in nutrient medium. The transcripts of MYST2 and hdaA were shown to decrease by10 and 5 fold respectively in the presence of 2-phenylethanol.