Guaymas Basin hydrothermal sediments Targeted loci environmental
In the recent past we have gained substantial insights into the diversity and ecophysiology of autotrophic organisms inhabiting cold seeps and hydrothermal sediments. Yet, little is known about the heterotrophs that thrive in these ecosystems, and their role in the carbon cycle. Since organic carbon input to the deep-sea is very low, some heterotrophic organisms at seeps likely use the autochthonous organic carbon that was fixed by the autotrophs, thereby passing deep subsurface derived energy and carbon along the food chain. We hypothesize that seeps and vents harbor heterotrophs that are specialized on the degradation of dead microbial biomass and cell components. We incubated samples from two hydrothermal sediments and one reference site at Guaymas Basin obtaining over 100 enrichment cultures. The production of hydrogen, methane or both shows that, we enriched communities that specialized on the degradation of specific cellular components such as proteins, nucleic acids, lipids, or polysaccharides, using different electron acceptors under different temperature regimes. 16S rRNA gene amplicons, metagenomes and metaproteomes will reveal the involved populations and pathways, and elucidate trophic networks that are used to funnel deep carbon into ecosystems at the seafloor surface. Our research addresses an important gap in the understanding of cold seeps and hydrothermal vents, which are windows to the deep biosphere. The expected insights have implications not only for surface ecosystems, but also for communities and the carbon cycle in the deep marine subsurface. PI S. Emil Ruff, Marine Biological Laboratory. See also PRJNA635695.