蓖麻饼粕脱毒菌株的筛选及发酵条件的研究

目的]为了降低蓖麻饼粕中蓖麻碱和变应原的含量。方法]从自然霉变的蓖麻饼粕中分离对蓖麻碱和变应原具有较好脱毒效果的霉菌,命名为ZF-4,采用显微形态、特殊结构观察对分离菌株进行初步鉴定,并以蓖麻碱和变应原降解率为指标,采用单因素单因子法研究蓖麻饼粕与麦麸的比例、葡萄糖、KH2PO4添加量、固水比、发酵温度、初始pH、接种量、发酵时间等因素对蓖麻碱和变应原降解率的影响。在此试验结果的基础上,选择对蓖麻碱和变应原降解率影响较大的固水比、发酵温度、初始pH和接种量4个因素进行正交优化。结果]ZF-4被初步鉴定为根霉属。适宜的发酵培养基组成为:蓖麻饼粕与麦麸的比例为95∶5,葡萄糖1.5%,KH2PO40.25%,CaCO30.4%;适宜的发酵条件为:固水比1.0∶0.8,发酵温度28℃,初始pH 7.0,接种量10%,发酵时间6 d。在此条件下,蓖麻碱和变应原的降解率分别达到89.56%和96.79%。结论]该研究为蓖麻饼粕的微生物脱毒提供了理论依据。

Studies on Isolation of Degrading Strains of Castor Bean Meal and Its Fermentation Conditions

Objective ] The research aimed to decrease the content of ricinine and allergen of castor bean meal. Method ] A fungus with the de- toxification effect of ricinine and allergen was isolated from natural moldy castor bean meal,namecl as ZF-4, and was primarily identified by mi- cro-morphology and the special structure was observed. The effects of fermentation conditions such as the ratio of castor bean meal and wheat bran, glucose and KH2PO4 adding, the ratio of mateial to water, fermentation temperature, initial pH, and inoculum size and fermentation time on the degradation rate of ricinine and allergen were studied with the degradation rate of ricinine and allergen as index by using single-factor ex- periment. Then, the influence of the ratio of mateial to water, fermentation temperature, initial pH,and inoculum size on the degradation rate of ricinine and allergen was optimized by using orthogonal experiment. Result] The strain ZF-4 was primarily identified as Rhizopus. The optimal medium composition was as follows ： the ratio of castor bean meal and wheat bran was 95： 5, glucose 1.5%, KH2PO4 0.25% ,and CaCO3 0.4%. The optimal fermentation condition was as follows ： the ratio of mateial to water was 1.0： 0.8, fermentation temperature 28 ~C, initial pH 7.0, in- oculum size 10%, and fermentation time 6 d. Under these conditions, the degradation rate of ficinine and allergen reached 89.56% and 96.79% ,respectively. Conclusion] The study provided theoretical basis for the castor bean meal microbial detoxification.