牛羊粪中纤维素降解菌的筛选鉴定及产酶条件优化

Screening,identification and enzyme production conditions optimization of cellulose-degrading bacteria from the cow and sheep manure

该研究采用刚果红染色法和滤纸条崩解法从青海天然牧场的牛羊粪中分离筛选纤维素降解菌,通过形态学观察及分子生物学技术对筛选菌株进行鉴定。以羧甲基纤维素(CMC)酶活性为筛选指标,采用单因素试验及响应面试验对其产酶条件进行优化,并评价其对不同秸秆的降解效果。结果表明,筛选获得一株具有较高产纤维素酶活性的菌株BC-4,其被鉴定为索诺拉沙漠芽孢杆菌(Bacillus sonorensis)。单因素及响应面试验结果表明,该菌株最优产酶条件为发酵初始pH8,接种量2%,发酵温度35℃。在此优化条件下,菌株BC-4产羧甲基纤维素酶活性为93.7 U/mL。该菌株对不同秸秆均具有较好的降解效果,其中对菊芋秸秆降解率最高为26.3%。

The cellulose-degrading bacteria were isolated and screened fromthe cowand sheep manure in Qinghai natural pasturehe by Congo red staining method and filter paper strip disintegration method,and the screened strains were identified by morphological observation and molecular biological technique.Using carboxymethyl cellulose(CMC)activity as the screening index,the enzyme production conditions were optimized by single factor tests and response surface tests,and its degradation effect on different stalks was evaluated.The results showed that a strain BC-4 with high cellulase activity was identified as Bacillus sonorensis.The results of single factor and response surface tests showed that the optimal enzyme production conditions of the strain BC-4 were initial pH 8,inoculum2%and fermentation temperature 35℃.Under these optimal conditions,the activity of carboxymethyl cellulose produced by the strain BC-4 was 93.7 U/ml.The strain BC-4 had good degradation effect on different stalks,and the degradation rate of Jerusalemartichoke straw was 26.3%.