Study On The Detoxificaion Conditions And Screening Of Highly Effective Strains For Degrading Toxins Of Castor Bean Meal

Castor bean meal (CBM) with high concentration of protein is a very good resource of plant protein feedstuff. However, the potential of castor bean meal for animal feed is limited by the presence of harmful components:an alkaloid called ricinine and a group of allergens (protein polysaccharides) known as CB-1A. The purpose of this research is proceed from improving the added value of agricultural by products and enlarging sources of animal feed protein to investigate a microbial fermentation method to detoxification of castor bean meal. In the present study, three strains with high efficiency of ricinine and allergen detoxification was screened out; the composition of culture medium and process parameters for fermentation detoxification was optimized; the mixed cultures fermentation and its process parameters were also investigated.Through the single-factor and orthogonal experiment, the optimum condition for ricinine extraction with microwave extraction technology was determined:ratio of solid to liquid was1:30, extraction time was28minutes, microwave power was595W. The speed of microwave extraction is quicker, but extraction rate is lower compared with chloroform extraction.The medium containing ricinine and allergen were used for plate screening. Castor bean meal was employed for practically biological fermentation. Through these methods, two gram negative bacterium named BF, BC and a Candida utilis named SJM with high efficiency of ricinine and allergen detoxification were screened out. The cell shape of Candida utilis SJM was oval, and its reproduction was by budding. Cultured by malt extract medium, yeast body was usually sunk to the bottom of test tube. Cultured by malt extract solid medium, plate colony surface is smooth and could from pseudomycelium. The optimum time of inoculation of SJM and BF were20hours and BC was18hour.Through the single-factor and orthogonal experiment, the optimum composition of culture medium of SJM were as follows:castor bean meal85%, wheat bran15%. MgSO4·7H2O0.4%, CaCl20.2%, KH2PO40.4%. The optimal fermentation conditions for ricinine and allergen detoxification are incubation period of5days, incubation temperature at30℃. inoculum level10%, moisture content of solid substrate60%and pH in nature. Under such conditions the degradation rate of ricinine and allergen could be up to90.30%and93.78%. Crude protein content in fermented castor bean meal was increased by31.82%, up to44.53%.Optimize the process parameters for detoxification of ricinine and allergen in castor bean meal by BF and BC during solid substrate fermentation. The maximum detoxification efficiency of ricinine and allergen was achieved by employing the substrate which consists of80%of castor bean meal,8%of corn flour, and12%of wheat bran. The optimum fermentation conditions for ricinine and allergen detoxification are incubation period of4days, incubation temperature at39℃, inoculum level15%, moisture content of solid substrate70%and pH in nature. Under such conditions the degradation rate of ricinine and allergen could be up to91.47%and83.79%. Crude protein content in fermented castor bean meal was33.27%. It basically the same compared to non-fermented castor bean meal.