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.