Abstract
The hydrothermal vent system is a typical chemosynthetic ecosystem in which microorganisms play essential roles in the geobiochemical cycling. Although it has been well-recognized that the inorganic sulfur compounds are abundant and actively converted through chemosynthetic pathways, the sulfur budget in a hydrothermal vent is poorly characterized due to the complexity of microbial sulfur cycling resulting from the numerous parties involved in the processes. In this study, we performed an integrated metagenomic and metatranscriptomic analysis on a chimney sample from Guaymas Basin to achieve a comprehensive study of each sulfur metabolic pathway and its hosting microorganisms and constructed the microbial sulfur cycle that occurs in the site. Our results clearly illustrated the stratified sulfur oxidation and sulfate reduction at the chimney wall. Besides, sulfur metabolizing is closely interacting with carbon cycles, especially the hydrocarbon degradation process in Guaymas Basin. This work supports that the internal sulfur cycling is intensive and the net sulfur budget is low in the hydrothermal ecosystem.
Highlights
Hydrothermal vents are often discovered in ocean ridges where hydrothermal fluid is emitted after the hydrothermal circulation and alteration of seawater entrained through geothermally heated subseafloor basalt (Von Damm, 1990)
We performed an integrated metagenomic and metatranscriptomic analysis on a chimney sample from Guaymas Basin to achieve a comprehensive study of each sulfur metabolic pathway and its hosting microorganisms and constructed the microbial sulfur cycle that occurs in the site
Since the discovery of the deep-sea hydrothermal ecosystem in 1977, it has been proposed that hydrogen sulfide-oxidizing chemoautotrophs may potentially sustain the primary production in these ecosystems (Kvenvolden et al, 1995), where hydrogen sulfide or sulfide is primarily supplied via the high temperatures of seawater-rock interactions in the subseafloor hydrothermal reaction zones (Jannasch and Mottl, 1985)
Summary
Hydrothermal vents are often discovered in ocean ridges where hydrothermal fluid is emitted after the hydrothermal circulation and alteration of seawater entrained through geothermally heated subseafloor basalt (Von Damm, 1990). In the Lau Basin hydrothermal vent field, sulfur-oxidizing Alphaproteobacteria, Gammaproteobacteria, and Epsilonproteobacteria have been suggested to be dominant in the exterior chimney, whereas putative sulfur-reducing Deltaproteobacteria are dominant in the interior of the chimney (Sylvan et al, 2013). In the Guaymas Basin hydrothermal vent field, sulfate-reducing microorganisms, e.g., Desulfobacterales, have been detected and are hypothesized to be involved in the anaerobic methane-oxidation process (Biddle et al, 2012). The sulfur cycling is alternated by the chemical reactions that occur during the emitting and growth of the hydrothermal vent. A better understanding of sulfur cycling is essential for describing the geobiochemistry and providing hints to identify the life status of a hydrothermal vent ecosystem
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