Thermal Structuring and Functional Perseverance of Microbial Communities in Guaymas Basin Hydrothermal Sediments

The Guaymas Basin in the Gulf of California is characterized by active seafloor spreading, hydrothermal activity and organic matter accumulation at high deposition rate. The microbial community composition and their coexistence pattern in its hydrothermal sediments are influenced by thermal and geochemical gradients, for example the availability of energy and carbon sources such as methane, sulfate, hydrocarbons, and volatile organic acids. GC percentage analysis reveals that the entire microbial community in every sediment sample adapts to its local temperature regime, by adjusting its composition between and also within major phylogenetic lineages, as shown by analyses of the Atribacteria and Bathyarcheia. While the microbial communities change continuously in composition along the thermal spectrum of Guaymas Basin sediment cores, they consistently maintain their biogeochemical functions, for example in sulfur and methane cycling. This functional redundancy across different microbial lineages enables the microbial community to tolerate environmental changes along hydrothermal gradients.