一株纤维素降解细菌的筛选、鉴定及产酶条件分析

目的筛选高活性的纤维素降解细菌,并进行初步鉴定和产纤维素酶条件分析。方法采集吉首旗帜山松树林的土壤样品,通过富集培养和刚果红平板染色法筛选分离纤维素降解细菌;通过形态观察、生理生化特性检测和基于16S rRNA基因序列的系统发育分析对分离的菌株进行初步鉴定。利用单因素实验对产纤维素酶条件进行优化。结果分离获得1株高活性纤维素降解细菌JDM11,初步鉴定其为Bacillus velezensis;菌株JMD11产纤维素酶最佳培养温度、最适初始pH和培养时间分别为28℃、7.0～7.5和32h,在该条件下其滤纸酶(FPase)和羧甲基纤维素酶(CMCase)活力分别为260.32U/ml和651.75U/ml。结论菌株JDM11是1株高活性纤维素降解的Bacillus velezensis。

Isolation and identification of a cellulose-decomposing bacterium and its cellulase-producing conditions

Objective To screen highly active cellulose-decomposing bacteria,identify the isolated strains preliminarily and optimize their cellulase-producing conditions. Method Highly active cellulose-decomposing bacteria were isolated from the soil of pine forest in Qi-zhi mountain,Jishou by enrichment culture and Congo red staining test. The isolated strains were identified by bacterial morphological,physiological and biochemical characteristics,and phylogenetic relationships based on 16S rRNA gene sequences. The cellulase-producing conditions of these bacteria were analyzed by single factor experiments. Result A highly active cellulose-decomposing strain JDM11 was isolated from the soil samples,and identified as Bacillus velezensis by morphological,physiological and biochemical characteristics,as well as the phylogenetic analysis of 16S rRNA gene. The optimal cellulase-producing conditions of JMD11 were as follows：cultivation temperature at 28 ℃,initial pH of cultural medium 7.0-7.5 and cultivation time of 32 h,under which the activities of filter paper enzyme （FPase） and carboxymethyl cellulase （CMCase） reached 260.32 U/ml and 651.75 U/ml respectively. Conclusion The JDM11 strain is an efficiently cellulose-decomposing Bacillus velezensis.