产纤维素酶放线菌的筛选鉴定及其对玉米秸秆的降解

Screening and identification of a cellulase-producing actinomycete and its degradation of corn straw

从寒地黑土中筛选得到一株对纤维素具有降解能力的菌株,观察该菌株的形态特征并对其进行分子生物学鉴定。采用响应曲面法对该菌株降解玉米秸秆的条件进行优化,并对玉米秸秆降解前后的结构变化、主要成分变化进行观察和测定。结果表明:该菌编号为GS-4-21,其透明圈与菌落直径的比值(D/d)为5.54±0.20,滤纸酶活、纤维素外切酶活、纤维素内切酶活和β-糖苷酶酶活分别为11.94±0.51、12.07±0.43、32.94±0.83和30.87±1.04 U/mL。经鉴定菌株GS-4-21属于链霉菌属。当以体积分数3%接种至pH为6的发酵培养基中,28℃、160 r/min发酵5 d时,玉米秸秆的降解率可达23.54%。SEM结果表明:菌株GS-4-21具有较好的纤维素降解能力。玉米秸秆中纤维素、半纤维素、木质素的降解率分别为30.33%、31.95%、18.91%。

A strain with the ability to degrade cellulose was selected from the black soil in the cold region.The morphological characteristics of the strain were observed and molecular biological identification was carried out.The response surface method was used to optimize the conditions of corn straw degradation by the strain,and the changes of structure and main component of corn straw before and after degradation were observed and determined.The results showed that the strain number was GS-4-21,and the ratio of the transparent circle to colony diameter(D/d)was 5.54±0.20.The enzyme activities of filter paper,exocellulase,endocellulase andβ-glycosidase were 11.94±0.51,12.07±0.43,32.94±0.83 and 30.87±1.04 U/m L,respectively.The identified strain GS-4-21 belonged to the genus Streptomyces.The degradation rate of corn straw reached 23.54%when the inoculation amount was 3%(volume fraction),initial pH of the culture medium was 6,fermentation time was 5 d,fermentation temperature was 28℃,and rotating speed was 160 r/min.SEM results demonstrated that strain GS-4-21 had better cellulose degradation ability.The degradation rates of cellulose,hemicellulose and lignin in corn straw were 30.33%,31.95%and 18.91%,respectively.