Exploring the Microbial Geobiological Pattern Across the Serpentinization Sites through Metagenomic and Elemental Composition Analyses

It is well-known that ultramafic rocks can continuously generate hydrogen through the serpentinization process associated with dynamic geochemical and geobiological interactions. This study aims to gain an improved understanding of these dynamic processes through the understanding of diverse microbial populations in order to maximize the geologic hydrogen production potential. The water samples were collected from a near surface serpentinite site in Northern California, USA. Elemental analyses of these water samples revealed the presence of essential dissolved minerals such as magnesium, calcium, and potassium, along with trace elements including iron, cobalt, and nickel. These elements act as cofactors for enzymes involved in microbial metabolic processes and Non-metric Multidimensional Scaling analysis supports this corelation. Furthermore, the analysis of total organic carbon (TOC) showed significant levels of organic carbon, suggesting a link with biological carbon cycling processes. Metagenomic analysis uncovered a diverse microbial community of hydrogen-fueled microbial consortia at the sampling sites, encompassing hydrogenogenic and hydrogenotrophic microorganisms. We examine hydrogen-metabolizing communities, including sulfate-reducing bacteria, acetogens, and methanogens, supported by diversity in hydrogenase enzymes across various sampling sites. These observations are corroborated by genomic accession data and abundance profiling of genes associated with acetogenesis, methanogenesis, and carbon monoxide metabolism. These investigations provide new insights into hydrogen-metabolizing microorganisms in northern California and propose frameworks for optimizing hydrogen production through the inhibition of hydrogen metabolism.