GENETIC & METABOLIC ADAPTATION BY SALMONELLA TO THE NATURAL ENVIRONMENT

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。沙门氏菌通常被认为是一种低频率、共生和低级别的病原体，在宿主生物以外的环境中长期生存的能力非常有限。最近的研究发现了一系列相互作用的代谢功能，这些功能在所有沙门氏菌中都是共享的，但在其最近的近亲大肠杆菌中却不存在。沙门氏菌特有的功能包括从头合成钴胺(B12)，利用B12降解乙醇胺和丙二醇，将四硫酸盐厌氧呼吸转化为硫代硫酸盐(TTR基因)，以及随后还原为亚硫酸盐(PHS基因)和硫化物(ASR基因)。当沙门氏菌在乙醇胺或丙二醇上厌氧生长时，在存在可还原硫化物的情况下，所有这些功能都将被使用。在这些条件下，沙门氏菌形成矿物质硫颗粒，它(但不是大肠杆菌)可以在以后通过需要PHS基因的过程来还原这些颗粒。虽然这些功能在发病机制中可能很重要，但我们认为它们更有可能表明沙门氏菌在特定的土壤环境中具有重要的生活方式。我们的工作旨在了解沙门氏菌是否存在环境生态位，以及这种生态位对我们理解这种生物的发病机制将产生的潜在影响。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Salmonella is generally considered a low-frequency commensal and low-grade pathogen with very limited ability to survive long term in the environment outside of a host organism. Recent work has identified a constellation of interactive metabolic functions shared by all Salmonellae, but absent from its nearest relative E. coli. The constellation of Salmonella-specific functions includes de novo synthesis of cobalamin (B12), use of B12 in degradation of ethanolamine and propanediol, anaerobic respiration of tetrathionate to thiosulfate (ttr genes), and subsequent reduction to sulfite (phs genes) and sulfide (asr genes). All these functions would be used when Salmonella grows anaerobically on ethanolamine or propanediol in the presence of reducible sulfur compounds. Under these conditions, Salmonella forms granules of mineral sulfur, which it (but not E. coli) can later reduce by a process that requires the phs genes. While these functions may be important to pathogenesis, we think it more likely that they suggest a significant lifestyle for Salmonella in particular soil environments. Our work has been geared to understanding whether there is an environmental niche for Salmonella and the potential impact that such an ecological niche will have on our understanding of the pathogenesis of this organism.