参与DMSP/DMS循环的极地细菌初步筛选及其多样性研究

Preliminary Screening of Polar Bacteria Participating in DMSP/DMS Cycle and the Diversity Analysis

为解决目前对极地环境中参与二甲基巯基丙酸内盐/二甲基硫(DMSP/DMS)循环的细菌类群多样性的认知仍十分有限的问题,本文作者依托本实验室建立的极地微生物资源库,利用气相色谱法对南北极来源的174株细菌进行了DMSP降解和合成活性初步筛选,并对获得的活性菌株进行多样性分析。研究发现具有DMSP降解活性的极地细菌有57种、103株,占总细菌种数约59.2%,以γ-变形菌纲、α-变形菌纲为主,其中43.7%的潜在DMSP降解菌兼具脱甲基和裂解途径;具有DMSP合成能力的极地细菌有25种、28株,占总细菌种数16.1%,以γ-变形菌纲的假单胞菌属、嗜冷杆菌属、海杆菌属和黄杆菌纲的黄杆菌属等为主,其中17株合成菌兼有降解DMSP的脱甲基和裂解途径,2株细菌的DMSP合成能力较强,分别是成都假单胞菌(Pseudomonas chengduensis)和栖藻黄杆菌(Flavobacterium algicola)。研究还发现在可培养菌株样品中,南、北极来源的功能细菌类群在属水平上存在较大差异。研究结果表明参与DMSP/DMS循环的细菌种类繁多,且在极地环境中广泛存在。

DMSP/DMS plays an important role in driving the global sulfur cycle and climate regulation, while marine bacteria are important producers and decomposers of DMSP. In addition, as an important cryoprotectant, the DMSP/DMS produced by polar microorganisms may be higher than other sea areas. In order to solve the problem that the diversity of bacterial groups participating in the DMSP/DMS cycle in the polar environment was unknown, the study was conducted relying on the polar microbial resource bank established by our laboratory, 174 strains isolated from Arctic and Antarctic were preliminarily screened for DMSP degradation and synthesis activity by gas chromatography, then analyzed for diversity of the obtained active strains. The results showed that a total of 103 strains within 57 species of polar bacteria with DMSP degradation activity were obtained, accounting for about 59.2% of the total number of bacteria estimated. These active strains were mainly composed of gammaproteobacteria and alphaproteobacteria, of which 43.7% were concurrently with demethylation and cleavage pathways. 28 strains within 25 species showed the ability to synthesize DMSP, accounting for 16.1% of the total number of bacteria, including Pseudomonas, Psychrobacter, Marinobacter of gammaproteobacteria, Flavobacterium of Flavobacteriia, and so on. Among them, 17 DMSP synthetic strains have both demethylation and cleavage pathways to degrade DMSP, and two other strains have strong DMSP synthesis ability, which were identified as Pseudomonas chengduensis and Flavobacterium algicola. It was also found that in the culturable bacteria samples, there were significant differences in the functional bacterial groups from the north and south poles at the genus level. The study showed that a variety of groups of bacteria involved in the DMSP/DMS cycle were widespread in the polar environment.