Antifungal Activity, Biodegradation and Production Inhibition of Aflatoxins B1 and G1 by a Soil Isolate of Bacillus subtilis against Aspergillus parasiticus NRRL 2999

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.

Abstract     

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.