Fatemeh Siahmoshteh1,Zohreh Hamidi-Esfahani1* and Mehdi Razzaghi-Abyaneh2
1Department of Food Science and Technology, Faculty of Agriculture,
Tarbiat Modares University, Tehran, Iran.
2Department of Mycology, Pasteur Institute of Iran, Tehran – 13164, Iran.
Aflatoxins, the most potent carcinogenic mycotoxins, are mainly produced by Aspergillus flavus and Aspergillus parasiticus. Different strategies have been used to control aflatoxin-producing fungi in field and storage conditions. In this study, a field isolate of Bacillus subtilis examined for its ability to inhibit the growth, spore germination and aflatoxin production by A. parasiticus NRRL 2999. Aflatoxin degradation and cell wall adsorption were also tested. Aflatoxins B1 and G1, the most potent carcinogens, were measured qualitatively by HPLC. According to the results, B. subtilis culture filtrate suppressed fungal growth and spore germination by 0-100% and 0-38% at different concentrations, respectively. The bacterium inhibited aflatoxins B1 and G1 more than 90% in 750 µl concentration. In addition to the aflatoxin production inhibition, the bacterial cells degraded the aflatoxins B1 and G1 in liquid medium up to 60% but there was no aflatoxin which could be adsorbed by the cell wall of the bacterium. The inhibitory potentials of this isolate could be extended to direct use of this strain in the market or as a biological control agent in the field to prolong the shelf life of commodities.
Keywords: Biodegradation, Bacillus subtilis, Aspergillus parasiticus, Aflatoxin, Antifungal activity.