Study On Degradation Of Bacillus Subtilis BS-02 To Aflatoxin In Corn

Aspergillus flavus is a pathogen of human, animal and plant. It can invade crops and produce AFTs during corn storage. AFTs can cause teratogenic, mutagenic and carcinogenic and threat the health and living environment of human being and animal, result huge economic losses to the feed industry and livestock. It is a matter of the utmost urgency to find out a microbiological detoxification method to remove the AFTs. At present, the studies on Aspergillus flavus and/or AFTs are focusing on pesticides and biological control, which include directly using synthetic antagonistic microbes and extracting antifungal compounds from Chinese Herbal Medicine(TCM) and microorganisms to inhibit and degrade Aspergillus flavus growth, spore germination and AFTs. Although many methods have been used to against Aspergillus flavus and/or AFTs up to now, it was not always effective. We found that the Bacillus subtilis BS-02 which have high degradation effect of AFTB1, the determination of degradation efficiency of AFTB1 and the optimized condition on how Bacillus subtilis BS-02 SSF to degrade AFTB1 were researched in this experiment.In the present study, single factor experiment and orthogonal experiment were used to study the degradation of aflatoxin B1 by Bacillus subtilis BS-02 solid state fermentation. Single factor experiment showed that the optimum condition is that the incubation temperature was 35℃, fermentation time was 60 h, the inoculation size ratio was 10%, meal to water was 1:1 and p H was 7.5. Orthogonal experiment was carried among the five principal factors. Result showed that the optimum condition of AFB1 degradation was obtained as follows: inoculation amount 15%, optimum temperature 40 ℃, p H 8.0, 48 h and meal to water was one to one point 1:1, with 81.4% degradation ration of the AFTB1.Bacillus subtilis BS-02 solid fermentation of corn flour and protein, sugar, fat and ash component changes the results showed that fermented crude protein content in corn flour increased, increased the amount of 15.95%. Total sugar content decreased, the decrease of 15.3%, ash and fat contents increased 5.05% and 3.5%.Determination of the saturated solution of ammonium sulfate as the crude extraction method from the comparison of ammonium sulfate precipitation and ethanol precipitation method. And through the Sephadex G-25 column chromatography separation and purification culture liquid of antibacterial protein, on the degradation of Aspergillus flavus toxin B1 and biological characteristics research, the results showed that the thermal stability of antibacterial protein better; p H in neutral or slightly alkaline conditions stable; in alkaline and neutral protease resistance is weak; the organic solvent with tolerance; ninhydrin and biuret reaction were positive. Separation and purification of antifungal protein has inhibitory effect on many kinds of pathogenic fungi, but on Escherichia coli, Staphylococcus aureus and Micrococcus luteus is invalid. UV analysis has 3 peaks, second peaks, followed by 3 drops, and has a strong role in the degradation of aflatoxin B1.