深海嗜冷希瓦氏菌Shewanella psychrophila WP2的基因组学分析

Genomic analysis of the psychrophilic deep-sea bacterium Shewanella psychrophila WP2

嗜冷希瓦氏菌Shewanella psychrophila WP2分离自深海沉积物,其拥有目前希瓦氏菌属(Shewanella)中最大的基因组,为6.4 Mb。通过对S.psychrophila WP2的完整基因组进行系统发育和代谢潜能分析,并与相近菌株进行比较,探究WP2拥有较大基因组的生理和生态意义,深化对Shewanella菌在环境适应性方面的认识。基于串联保守蛋白对WP2基因组进行系统发育分析,根据注释结果对WP2进行代谢通路重建。系统发育进化树显示,WP2属于Group 1分支,和其它嗜冷嗜压Shewanella菌相同,非嗜冷嗜压Shewanella菌株都属于Group 2分支。WP2基因组中与DNA修复、次级代谢产物合成、转运分泌相关的基因数明显多于Shewanella piezotolerans WP3。WP2拥有较多水平转移来源的基因组岛(17个),岛内包含了与嘌呤代谢、氨基糖代谢、运动趋化、群体感应等功能相关的基因。结果表明,通过潜在的水平基因转移,WP2获得了大量的辅助功能基因,增强了它的氮源利用能力、运动和趋化能力,以及应对复杂环境的群体感应能力和抗生素合成功能,从而更加适应生活在寡营养和复杂极端的深海环境。本研究针对S.psychrophila WP2的代谢潜力进行了深入的探索和研究,为将来关于Shewanella菌和微生物的环境适应机制的研究提供了更多数据参考和理论基础。

The psychrophilic and barotropic bacterium Shewanella psychrophila WP2 was previously isolated from deep-sea sediments.Intriguingly,S.psychrophila WP2 possesses the largest genome(6.4 Mb)among Shewanella genus.In this study,the phylogenetic and metabolic potentials of S.psychrophila WP2 were investigated to deepen the understanding of the environmental adaptability of benthic microbes.The phylogenetic tree shows that psychrophilic/piezotolerant(including S.psychrophila WP2)and mesophilic pressure-sensitive Shewanella strains belong to the Group 1 and Group 2 branches,respectively.The number of genes involved in DNA repair,secondary metabolite synthesis and transport secretion in the S.psychrophila WP2 genome are significantly higher than that of S.piezotolerans WP3.Besides,S.psychrophila WP2 harbors 17 genomic islands which contain a variety of genes related to purine metabolism,amino sugar metabolism,motility,chemotaxis and quorum sensing as well as antibiotic secretion.Moreover,the results demonstrate that deep-sea bacterium acquires a large number of functional genes which have enhanced its abilities of nitrogen source utilization,moving and chemotaxis,as well as group sensing to the complex environment and synthesis of antibiotics for more adaptation in oligotrophic and complex extreme deep sea environment.This study has conducted profound exploration and research on the metabolic potential of S.psychrophila WP2.It provides additional data reference and theoretical basis for future research on the environmental adaptation mechanism of Shewanella and microorganisms.