一株产纤维素酶的解淀粉芽孢杆菌的分离鉴定及其酶促反应适宜条件初步研究

摘要

In order to isolate and screen strain which can degrade corn stalk,and study its enzyme-reaction conditions,a cellulose-producing strain was isolated from corn silage by carboxymethyl cellulose-Na (CMC-Na)medium and Congo red.Morphological and 16S rDNA gene were analyzed to identify the taxonomic position of the strain.Meanwhile,the effects of culture time,pH and temperature on the activity of cellulase in the fermentation broth were studied.A strain which could degrade carboxymethyl cellulose-Na was obtained,with a clear hydrolysis circle around it.The morphological and Phylogenetic analysis based on 16S rDNA sequence showed that the strain was Bacillus amyloliquefacien.In the crude enzyme liquid,the filter paper enzyme activity was 1.5 U/mL,exoglucanases activity 1.3 U/mL,endoglucanases activity 6.4 U/mL,β-glucosidases activity 2.3 U/mL.The suitable conditions for enzymatic reactions were pH5.5 and 50 ℃,the crude enzyme liquid is the supernatant of the fermentation liquid of 3 days.The strain has cellulase-producing ability,and potential value in the biodegradation and utilization of corn stalk.%为了分离、筛选产纤维素酶益生菌,确定其酶促反应适宜条件,利用羧甲基纤维素钠等作为筛选培养基,结合刚果红染色法,从玉米青贮饲料样品中筛选产纤维素酶益生菌,并通过形态学和系统进化树方法鉴定分离菌.同时对培养时间、pH和温度等酶促反应条件进行了研究.结果表明,筛选出1株可降解羧甲基纤维素,并产生清晰透明圈的菌株.经形态学观察和16S rRNA基因序列分析,鉴定该菌为解淀粉芽孢杆菌(Bacillus amyloliquefaciens).粗酶液中滤纸酶活为1.5 U/mL,外切葡聚糖酶活为1.3 U/mL,内切葡聚糖酶活为6.4 U/mL,β-葡萄糖苷酶活为2.3 U/mL.酶促反应的适宜条件为pH 5.5,温度50℃,粗酶液为培养3d后发酵液上清.解淀粉芽孢杆菌分离株具有一定的产纤维素酶能力,在玉米秸秆生物降解与利用方面具有潜在的开发价值.