一株可利用二甲基巯基丙酸内盐生长的北极海洋细菌的分类鉴定及表型特征分析

IDENTIFICATION AND PHENOTYPIC CHARACTERIZATION OF AN ARCTIC MARINE BACTERIUM GROWN ON DIMETHYLSULFONIOPROPIONATE

二甲基巯基丙酸内盐(DMSP)是一种主要由海洋浮游植物生成的含硫化合物,在海洋中含量丰富,同时也是海洋细菌的重要营养物之一。采用生长选择性培养基从北极王湾海水中分离到一株细菌DMSP-1。基于16S rRNA基因序列及基因组平均核苷酸一致性(Average Nucleotide Identity,ANI)分析,将该菌鉴定为乳酸假单胞菌。该菌细胞呈杆状,有极生鞭毛;具有耐冷(可在5℃较快生长,适宜生长温度范围为22~29℃,最高生长温度为38℃)、耐盐(适宜生长盐度范围为0~4%NaCl、最高生长盐度为8%NaCl)等特性,表明该菌能较好地适应其所处的北极近岸环境。碳源生长实验证实该菌能以DMSP为唯一碳源进行生长。该菌具有乳酸假单胞菌的许多生理生化特征,但也存在差异,如色氨酸脱氨酶与脲酶为阳性、不能利用鼠李糖产酸等。对假单胞菌DMSP-1开展进一步的研究,将推动人们对于海洋细菌降解DMSP的代谢机制及其在北极海洋环境中生态功能的深入认识。

Dimethylsulfoniopropionate(DMSP) is a highly abundant sulfur-containing compound in marine environments. It is mainly produced by marine phytoplankton, and can act as a key nutrient for marine microorganisms. Strain DMSP-1 was isolated from Arctic seawater of Kongsfjorden using a selective growth medium. Based on the 16 S rRNA gene sequence and genomic ANI(Average Nucleotide Identity) analyses, the bacterium was classified and identified as the species Pseudomonas lactis. The bacterial cells were rods with polar flagella. The strain was psychrotrophic(growing well between 22 and 29℃ with an upper temperature limit at 38℃) and halotrophic(growing well between 0 and 4% NaCl with an upper salinity limit at 8% NaCl), indicating adaptation to the local habitat. A carbon source for growth experiment confirmed that strain DMSP-1 could grow with DMSP as the sole carbon source. The bacterium showed many genotypic characteristics similar to the type strain Pseudomonas lactis WS 4992T. At the same time, in contrast with P. lactis WS 4992 T, strain DMSP-1 showed tryptophan deaminase and urease activity, and was unable to produce acid from rhamnose. Further research on Pseudomonas sp. DMSP-1 will provide deep insight into the mechanism of marine bacteria degrading DMSP and their ecological functions in the Arctic marine environment.