Bacillus pumilus XJU-13的分离鉴定及其碱性脂肪酶酶学特性分析

目的:对从新疆精河地区一处工业污水中分离得到的一株产碱性脂肪酶细菌进行研究.方法:通过生理生化检测,16SrDNA序列同源性分析和G+Cmol%含量的测定对命名为XJU-13的这株菌进行鉴定.结果:该菌株可在pH 3.0～12.5的广泛酸碱泛围的营养肉汤培养基中生长.最适生长温度为37℃.基于16S rDNA序列同源性构建系统进化树分析表明与Bacillus pumilus clone B257聚在同一亚分枝,序列相似性达100%.数据证明XJU-13属于Bacillus pumilus.由于在氧化酶反应及淀粉水解实验与伯杰氏鉴定手册有差异,具不可比拟的pH耐受性,且脂肪酸含量与参考菌株差异较大,认为这是Bacillus pumilus中的一个新品系.该菌株产生的脂肪酶最适pH为10,最适温度为35℃,且在广泛pH(pH4-10)范围具稳定性.酶活可被Mg2+、K+、Ba2+、Pb+盐强烈抑制,被Ca2+、Cu2+、Al+及Fe2+盐激活.Zn2+对酶活无影响.结论:实验表明,XJU-13应属于B.pumilus.B.pumilus XJu-13中分离到的碱性脂肪酶有很好的特性及潜能,以期为工业应用提供数据.

Isolation, Identification, and Characterization of Bacillus pumilus XJU-13, an Alkaline Lipase- producing Bacterium

Objectlve:An alkaline lipase- producing bacterial strain was studied originally isolated from an industrial sewage at Jinghe County of Xinjiang, China. Method:The strain designated as XJU-13 was characterized in terms of physiological and biochemical characteristics, 16S rD-NA sequence homology, and G+ C mol%. Result:The strain can grow in nutrient broth at a broad range of pH values (3.0-12.5). And the optimum temperature of growth was around 37℃. Phylogenetic analysis of the strain based on comparison of 16S rRNA sequence revealed that it is closely related to Baclllus pumilus clone B257 with 100% identity, and the G + C content of its genomic DNA is 41.57 mol%. Owing to the da-ta of oxidase reaction and starch hydrolysis test different from those of B. pwnilus KT1012,the excellent pH tolerance, and the discrepancy with reference strain in the Bergey's Manual of Systemaie Bacteriology, the strain was further classified as a new member of the species B. pumilus. The extracellular alkaline lipase isolated from the culture broth of the strain was stabile over a broad pH range (pH4-10), with the optimum pH and temperature being 10 and 35℃, respectively. It was inhibited strongly by Mg2+, K+, Ba2+and Pb+ , and enhanced by Ca2+ , Cu2+, Al3+and Fe2+ . Zn2+ has no effects on its activity. Conclusion:The results demonstrated that XJU-13 should be belonged to B. pumilus. Due to its excellent properties, the alkaline lipase may have great potential for biotechnological applications in the industry.