Collaborative Research: Determining Functional Correlations Between Geochemical Factors and Microbial Metabolisms in Ultrabasic Serpentinizing Ecosystems

对极端环境的研究，尤其是那些与地球早期普遍存在的条件相似的极端环境，不仅能让我们了解生命是如何在今天地球上最恶劣的地方生存下来的，还能让我们了解在很久以前，也许是生命出现之初，生命是如何生存下来的。这项工作将研究这种极端环境下的生命。这是一个蛇纹石化的地方，液体从地球上冒出来，pH值非常高，氧化还原电位非常低，几乎没有有机物可以吃，几乎没有氧气或其他东西可以呼吸：地球上最具挑战性的环境之一。先前对两个地球化学不同的高碱性地下水来源的研究表明，基因组和系统发育上不寻常的生物体和微生物分离物具有高度适应蛇纹石化环境的生理和基因组特征。在这里，pi将扩展他们之前的研究，重点关注与该地点发生的地球化学和微生物代谢相互作用相关的问题：例如，1)每个主要的微生物群/参与者如何应对the Cedars的严格地球化学，2)这些微生物如何相互作用以维持the Cedars蛇形化环境的分类稳定群落，以及3)微生物活动如何潜在地促进发生的地球化学转变？为了回答这些问题，pi将使用几种方法测试一些概念，战略和代谢假设，包括：1)结合先进的显微镜观察来可视化每个生物的定位，2)稳定同位素探测来识别利用给定碳底物的生物，3)刺激诱导的亚转录组学来说明基因对特定地球化学化合物（条件）的反应，4)宏蛋白质组学来获得原位蛋白质谱，5)在地球上陆地蛇纹石化地点大量观察到的分离菌株的详细代谢能力。成功整合这五种策略的结果有望在极端环境条件下相对简单的微生物群落中产生地球化学因子与微生物代谢活动之间的功能相互作用模型。

The study of extreme environments, especially those that are similar to conditions thought to be prevalent on early Earth, provide insights not only into how life ekes out an existence in the most hostile places on our planet today, but how it might have done so long ago, perhaps at the dawn of life. This work will examine life in such an extreme environment. It is a serpentinization site where liquids emerge from the Earth at very high pH, very low redox potential, with almost no organics to eat, and virtually no oxygen or other things to respire: one of the most challenging environments on Earth.Previous studies of two geochemically-different highly-alkaline groundwater sources revealed genomically and phylogentically unusual organisms and microbial isolates having highly-adapted physiological and genomic features to the serpentinizing environments. Here the PIs will expand their previous studies, focusing on questions related to the geochemical and microbial metabolic interactions occurring at this site: e.g., 1) how do each of the major microbial groups/players cope with the stringent geochemistry of The Cedars, 2) how do these microbes interact with one another to sustain the taxonomically stable communities of The Cedars serpentinizing environments, and, 3) how do the microbial activities potentially contribute to the occurring geochemical transformations? To answer these questions the PIs will test a number of conceptual, strategic and metabolic hypotheses, using several approaches, including: 1) a combination of advanced microscopic observations to visualize the localization of each organism, 2) stable-isotope probing to identify organisms that utilize a given carbon substrate, 3) stimulus-induced metatranscriptomics to illustrate the gene responses to the specific geochemical compounds (conditions), 4) metaproteomics to obtain the in situ protein profiles, and 5) detailed metabolic capabilities of isolated strains that are abundantly observed in terrestrial serpentinizing sites on Earth. Successful integration of results from these five strategies is expected to produce a functional interaction-model between geochemical factors and microbial metabolic activities in a relatively simple microbial community, functioning under extreme environmental conditions.