碱性果胶酶产生菌Bacillus claussi XJU-8的分离鉴定及酶学特性分析

Isolation and Identification of Bacillus claussi XJU-8 and Enzymatic Properties of Its Slkaline Pectinase

从新疆石河子市一处工业污水(pH11.0)中分离到一株碱性果胶酶产生菌,编号XJU-8。应用形态学检测、生理生化实验、16S rDNA序列分析、系统进化分析对菌株进行多相鉴定。XJU-8可在pH5.0～13.0的LB培养基上生长,最适生长温度37℃。16S rDNA序列构建的系统进化树表明XJU-8与Bacillus claussi类聚在一起,而且序列同源性高达99%以上。XJU-8与B.claussi GMBAE 42在氧化酶,柠檬酸盐利用和水解Tween-40、Tween-60上有差异,且XJU-8有宽范围pH值耐受性,被认为是B.claussi的一个新品系。该菌产生的碱性果胶酶最适pH10.0,最适温度50℃,在pH9.0～12.0有较高活性和稳定性。酶活性可被Ca2+盐激活。XJU-8所产碱性果胶酶特性良好,工业应用潜能巨大。

A bacterial strain designated as XJU-8 was isolated from alkaline sewage samples from Shihezi city,Xinjiang.This bacterial strain was a gram-positive,spore-forming,aerobic bacillus.It could grow in LB medium with a broad range of pH（5.0-13.0）.The optimal growth conditions for this bacterial strain were 37 ℃ and pH 10.5.Its tolerance to NaCl was up to 15%.The 16S rRNA gene sequence analysis showed that the strain XJU-8 was highly related to B.claussi with 99% similarity.The G＋C content in its genomic DNA was 43.67%.The strain XJU-8 was confirmed as B.claussi by comparing its physiological,biochemical and genetic characteristics with those of B.claussi GMBAE 42.Due to its excellent pH tolerance and several phenotypic characteristics,this strain was further confirmed and classified as a new member of B.claussi species.This strain also could produce an extracellular alkaline pectinase with the maximum enzyme activity at 50 ℃ and pH 10.0.More than 80% activity of this alkaline pectinase was remained at pH value ranging from 9.0 to 12.0.The activity of the alkaline pectinase could be enhanced in the presence of Ca2＋.These properties demonstrated that this enzyme might be suitable for paper-making,coffee and tea fermentation,textile industries and other industrial applications.