深海嗜冷细菌中原噬菌体的诱导机理及其功能研究

As the most abundant biological entities on the planet, bacteriophages significantly influence the life cycle of microbial hosts and the global biogeochemical cycles. Emerging evidences have indicated that benthic bacteriophages play an important role in the overall functioning of the deep-sea ecosystem. Nevertheless, little is known about how benthic phages are regulated and how they affect the extreme environmental adaptation of their bacterial hosts. As prophages are widespread in the genome of deep-sea microorganisms, it was speculated to regulate the micriobial physiology and function, thus influence the environmental adaptation of these microorganisms. To verify this hypothesis, the deep-sea psychrophilic bacterium Shewanella psychrophila WP2 and its integrated 3 prophages which belong to different virus families, will be used as the modal system in this study. The genomics, transcriptomics and proteomics methods, as well as the classic microbiology and molecular biology analysis will be conducted to characterize the lysogenic-lytic switch mechanism and its biological feature. The influence of prophages on the extreme environmental adaptation of WP2 will be our focus and the model of phage-host interaction will be constructed based on the above data. Moreover, in order to investigate the phage and host co-evolution, the in situ environmental simulation and comparative genomics analysis will be performed. Taken together, this study will contribute to the better understanding of the regulatory mechanism and ecological function of benthic bacteriophages in the deep-sea environment.

噬菌体是地球上丰度最高的生物体，它们显著地影响微生物宿主的生命活动和生物地球化学循环。已有研究表明深海噬菌体在深海生态系统中扮演着非常重要的角色，但是目前对深海噬菌体如何被调控以及它们如何影响宿主的极端环境适应性等科学问题尚未阐明。原噬菌体在深海微生物基因组中普遍存在，推测其具有调节宿主生理功能而影响其环境适应性的作用。为验证这一假设，本项目将以本实验室已有的深海嗜冷细菌Shewanella psychrophila WP2及其3个不同家族的整合型原噬菌体为材料，综合利用各种组学及经典的微生物学、分子生物学等手段，来系统研究原噬菌体的溶源-裂解转换的调控机制及其生物学特征，并将重点关注其对宿主细菌在深海极端环境下的作用和影响，构建噬菌体与宿主的相互作用模型。此外，还将通过原位环境模拟和比较基因组学对噬菌体-宿主的共进化进行分析，为阐明深海噬菌体对宿主的作用机理和生态学意义提供有用的参考。

噬菌体是地球上丰度最高的生物体，它们显著地影响微生物宿主的生命活动和生物地球化学循环。已有研究表明深海噬菌体在深海生态系统中扮演着非常重要的角色，但是目前对深海噬菌体如何被调控以及它们如何影响宿主的极端环境适应性等科学问题尚未阐明。原噬菌体在深海微生物基因组中普遍存在，推测其具有调节宿主生理功能而影响其环境适应性的作用。在本项目中，我们分析了深海嗜冷细菌Shewanella psychrophila WP2中原噬菌体的基本特征，发现其中一个原噬菌体SP1具有稳定的高切离频率，表型检测和转录组学分析表明SP1对宿主的氨基酸代谢和环境适应性具有显著影响。同时，我们还研究了深海丝状噬菌体SW1中自身调控因子FpsR的作用方式，发现其通过“空间位阻”和“路障”两种机制调节噬菌体基因的转录。进一步分析表明SW1的基因开关存在温度阈值，且可能广泛分布于海洋环境中。此外，通过对海洋希瓦氏菌基因组的分析，发现了其从表层到深渊的演化可分为两个不同的阶段。总体而言，以上研究成果将有助于更好地从微观角度阐明深海生态系统的组成以及物质能量循环过程，特别是噬菌体在其中的贡献及作用机制。