Study On The Solid State Fermentation Of Rapeseed Meal And Microbial Degradation Of Glucosinolate

Rapeseed meal(RSM) was widespread, and was an important vegetable protein raw material in feed. But some of the anti-nutritional factors, especially the glucosinolate, limited its use in feed. In order to increase the proportion of RSM in animal feed, it was focus on degrading the anti-nutritional factors and improving the utilized rate of rapeseed meal protein in the feed industry by microbial fermentation. The main contents and results were as follows:1. Through preliminary screening by transparent circle method and re-screening by determining the protease activity and the degradation rate of glucosinolate, the strains were screened out. The strains of BL-1、JEK-X、ND-3-D and JM3were high ability of protease activity, and the strains of ND-1-1、BSK-BL-2-D、BL-1、Candida lipolyticaand BS were better in degrading glucosinolate. The result of the combination experiment of mixed strains in RSM extract medium showed that the fermentation strains combination was BL-1+BS, and the degradation rate of glucosinolate was77%.2. The result of the solid-state fermentation with RSM as substrate showed that the optimum combination was BL-1+BS+Candida lipolytica, and the degradation rate of glucosinolate was64.6%, the glucosinolate residual volume was12.96μmol/g, the degradation rate of tannin was64.6%, acid soluble protein content (TCA-N) was increased from2.0%to21.8%.3. Considering the balanced of all kinds of amino acids,50%soybean meal was added to the solid-state fermentation on the basis of pure RSM in this study, it means the fermentation substrate was a mixture mixed with RSM and soybean in1:1. By using TCA-N, protein degree of hydrolysis (DH) as well as the enzyme cutting site effective value (EV), glucosinolate degradation rates as the main evaluation indicator, the best combination(BL-1+BS+Candida lipolytica)was obtained.The result of the orthogonal experiment of four factors and three levels showed that the optimal fermentation conditions such as material-water ratio, inoculant amount, incubating temperature and fermentation time were1:1.1,9%,37℃and48h,respectively. After fermentation under this conditions, the crude protein content was increased from49.5%to53.1%, the TCA-N content was increased from2.5%to27.2%, the degradation rate of glucosinolate was65.2%. The results of SDS-PAGE showed that the large molecular protein were degraded into the smallers lower thanl2KD.