慕士塔格冰芯细菌的生理特征以及葡萄球菌Muzt-D84 cspA基因序列分析

Physiological characteristics of isolates from the Muztag Ata ice core and sequence analysis of Staphylococcus equorum MuztD84 cspA gene

为了解冰川微生物的生理生长特征及其在极端寒冷环境条件下的冷适应特性,从慕士塔格冰芯分离菌株中选取了5个代表菌株,分别对这些菌株的生长温度和酸度范围进行了观测,并利用微生物冷诱导蛋白的保守氨基酸序列,设计了1对冷诱导基因csp的特异引物,并对其进行了PCR扩增.结果表明:慕士塔格冰芯中存在3种类型的微生物,其中嗜冷菌为Muzt-D8,其生长温度范围为0～23℃,最适生长温度为15℃;耐冷菌为Muzt-D7,Muzt-G32和Muzt-F01,其生长温度范围为0～40℃,最适生长温度为23℃;宽温菌为Muzt-D84,其生长温度范围为0～45℃,最适生长温度为30℃.研究还表明,Muzt-D84菌株在偏酸性条件下生长较好,而Muzt-G3菌株则适宜在中性环境中生长;且从Muzt-D84菌株中成功地克隆出了cspA基因片段.

In order to understand the adaptation of the microorganisms under the extreme cold environment conditions,the physiological characteristics of the 5 bacterial isolates from the Muztag Ata ice core under the different temperatures were investigated. The csp gene was also amplified by PCR technique and the specific primer targeted for the cold shock protein. The observation results showed that there were three phenotypes of microorganisms, psychrophiles growing from 0-23 ℃（the optimum temperature at 15 ℃）,psychrotolerant with growth range at 0-40 ℃ （the optimum temperature at 23 ℃）,and the ther-mophile with growth range at 0-45℃ （the optimum temperature at 30 ℃）. The observation also indicated the important influence of pH on the growth of the bacterial population,and their quantitative distribution on the glacier surface. The sequence analysis indicated that the obtained DNA fragment from the thermophile isolate Staphylococcus equorum Muzt-D84 belonged to the partial of cspA gene sequence. This is very helpful to the further molecular study of the mechanisms of the microbial adaptation to the cold condition. This study provided an evidence of the adaptation of the microorganisms to the extreme environments at molecular level.