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 cellulase-producing actinomycetes and degradation of corn straw

摘要:

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%。

Abstract:

A strain that has the ability to degrade cellulose was selected from the cold region and black glebe, and 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 for the degradation of corn stalk by this strain, and the structural changes and the main component changes of corn stalk before and after degradation were observed and determined. The results showed that the strain number was GS-4-21, and the ratio (D/d) of the transparent circle of the colony diameter was 5.54 ± 0.20. The enzyme activities of filter paper, exocellulase, endocellulase and β-glycosidase were 11.94±0.51, 12.07±0.43, 32.94±0.83 and 30.87±1.04 U/mL, respectively. The identified strain GS-4-21 belongs to the genus Streptomyces. When inoculated into the fermentation medium with pH 6 at a volume fraction of 3% and fermented at 28 ℃ and 160 r/min for 5 d, the degradation rate of corn stover reached 23.54%. SEM results show that the strain GS-4-21 had better cellulose degradation ability. The degradation rates of cellulose, hemicellulose and lignin in corn stover were 30.33%, 31.95% and 18.91%, respectively.