Dissolved organic carbon compounds in deep-sea hydrothermal vent fluids from the East Pacific Rise at 9°50′N

Abstract

Deep-sea hydrothermal vents are unique ecosystems that may release chemically distinct dissolved organic matter to the deep ocean. Here, we describe the composition and concentrations of polar dissolved organic compounds observed in low and high temperature hydrothermal vent fluids at 9°50'N on the East Pacific Rise. The concentration of dissolved organic carbon was 46 µM in the low temperature hydrothermal fluids and 14 µM in the high temperature hydrothermal fluids. In the low temperature vent fluids, quantifiable dissolved organic compounds were dominated by water-soluble vitamins and amino acids. Derivatives of benzoic acid and the organic sulfur compound 2,3-dihydroxypropane-1-sulfonate (DHPS) were also present in low and high temperature hydrothermal fluids. The low temperature vent fluids contain organic compounds that are central to biological processes, suggesting that they are a byproduct of biological activity in the subseafloor. These compounds may fuel heterotrophic and other metabolic processes at deep-sea hydrothermal vents and beyond.

Dissolved Organic Radiocarbon in the Eastern Pacific and Southern Oceans

“…Additionally, molecular techniques are needed to identify the source or sources of DOC to the deep Pacific. Optical analyses, Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR‐MS), and untargeted metabolomics have been used to analyze vent fluid DOC to find evidence of organic sulfur compounds and amino acids that have been interpreted as evidence of chemosynthesis (Grandy et al., 2020; Longnecker et al., 2018; Rossel et al., 2015). In situ analysis of vent fluid has been accomplished with Raman spectroscopy and liquid chromatography mass spectrometry (LC‐MS) (Camilli et al., 2009; White et al., 2006).…”

Soothsaying DOM: A Current Perspective on the Future of Oceanic Dissolved Organic Carbon

“…Based upon data collected from DOC isolated by solid phase extraction, which is presumed to represent the less biologically labile fraction of marine DOC, high temperature fluids remove an estimated 0.02 Tg-C of refractory DOC per year (Hawkes et al, 2015). However, this flux estimate only considers the extractable portion of DOC, which becomes smaller with increased temperature (Hawkes et al, 2015(Hawkes et al, , 2016 and largely excludes low molecular weight compounds (Klevenz et al, 2010;Lang et al, 2010;Fuchida et al, 2014;Reeves et al, 2014;McDermott et al, 2015;Longnecker et al, 2018). Hydrothermal vent-derived DOC may be a source of carbon for the deep ocean microbial communities (Winkel et al, 2014;Rossel et al, 2015), but fluxes have not yet been determined.…”

Marine dissolved organic matter: a vast and unexplored molecular space

“…Other studies proposed that putative amino acid–like and other compound classes were modified by bacterioplankton (Stephens et al 2020 ), significant release of peptides by viral lysis of Synechococcus (Ma et al 2018 ), and an association between elevated microbial community richness and DOM composition of temperate lake DOM (Muscarella et al 2019 ). Furthermore, via such metabolite profiling, dozens of metabolites (e.g., guanine, glutamic acid, phenylalanine, and ectoine) have also been determined in a variety of marine samples and as intracellular metabolites within marine microorganisms (Johnson et al 2020 ; Longnecker et al 2018 ; Longnecker and Kujawinski 2020 ).…”