Abstract
The discovery of deep-sea hydrothermal vents in the late 1970s widened the limits of life and habitability. The mixing of oxidizing seawater and reduction of hydrothermal fluids create a chemical disequilibrium that is exploited by chemosynthetic bacteria and archaea to harness energy by converting inorganic carbon into organic biomass. Due to the rich variety of chemical sources and steep physico-chemical gradients, a large array of microorganisms thrive in these extreme environments, which includes but are not restricted to chemolithoautotrophs, heterotrophs, and mixotrophs. Past research has revealed the underlying relationship of these microbial communities with the subsurface geology and hydrothermal geochemistry. Endolithic microbial communities at the ocean floor catalyze a number of redox reactions through various metabolic activities. Hydrothermal chimneys harbor Fe-reducers, sulfur-reducers, sulfide and H2-oxidizers, methanogens, and heterotrophs that continuously interact with the basaltic, carbonate, or ultramafic basement rocks for energy-yielding reactions. Here, we briefly review the global deep-sea hydrothermal systems, microbial diversity, and microbe–mineral interactions therein to obtain in-depth knowledge of the biogeochemistry in such a unique and geologically critical subseafloor environment.
Highlights
It has become increasingly apparent that microbial communities are not limited to shallow near-seafloor environments but could extend into the deep subsurface
We review, in brief, the dominant microbial diversity and community structure of deep-sea hydrothermal vents, microbe–mineral interactions, and the biogeochemistry involved in such unique ecosystems
Zetaproteobacteria Mariprofundus ferrooxydans [74,75] from the Loihi Seamount and Lau Basin [67], M. micogutta ET2 from the Izu-Ogasawara Arc [76], and several Alpha and gammaproteobacteria strains are reported as the chemoautotrophic Fe(II) oxidizers described from deep-sea vents [77] (Table 1)
Summary
It has become increasingly apparent that microbial communities are not limited to shallow near-seafloor environments but could extend into the deep subsurface. Hydrothermal vents form one such habitat, abundant in microbial communities that harbor energy through processes largely different from the surface photosynthetic biosphere These structures are formed when superheated, mineral-rich hot water percolate cracks, fissures, and comes into contact with cold seawater. The third type of energy source has been suggested to occur at high temperature hydrothermal vents [25,26,27] In this process, hydrogen acts as the primary energy source, generated by the reaction of seawater with reduced metals in basaltic glass or Fe-rich minerals. Hydrogen acts as the primary energy source, generated by the reaction of seawater with reduced metals in basaltic glass or Fe-rich minerals We review, in brief, the dominant microbial diversity and community structure of deep-sea hydrothermal vents, microbe–mineral interactions, and the biogeochemistry involved in such unique ecosystems
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