National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 2016

Hydrogen and thiosulfate limits for growth of a thermophilic, autotrophic Desulfurobacterium species from a deep-sea hydrothermal vent

Stewart, L.C., J.G. Llewellyn, D.A. Butterfield, M.D. Lilley, and J.F. Holden

Environ. Microbiol., 8, 196–200, doi: 10.1111/1758-2229.12368 (2016)

Hydrothermal fluids (341°C and 19°C) were collected < 1 m apart from a black smoker chimney and a tubeworm mound on the Boardwalk edifice at the Endeavour Segment in the northeastern Pacific Ocean to study anaerobic microbial growth in hydrothermal mineral deposits. Geochemical modelling of mixed vent fluid and seawater suggests the mixture was anoxic above 55°C and that low H2 concentrations (79 μmol kg−1 in end-member hydrothermal fluid) limit anaerobic hydrogenotrophic growth above this temperature. A thermophilic, hydrogenotrophic sulfur reducer, Desulfurobacterium strain HR11, was isolated from the 19°C fluid raising questions about its H2-dependent growth kinetics. Strain HR11 grew at 40–77°C (Topt 72–75°C), pH 5–8.5 (pHopt 6–7) and 1–5% (wt vol−1) NaCl (NaClopt 3–4%). The highest growth rates occurred when S2O32− and S° were reduced to H2S. Modest growth occurred by NO3 reduction. Monod constants for its growth were Ks of 30 μM for H2 and Ks of 20 μM for S2O32− with a μmax of 2.0 h−1. The minimum H2 and S2O32− concentrations for growth were 3 μM and 5 μM respectively. Possible sources of S2O32− and S° are from abiotic dissolved sulfide and pyrite oxidation by O2.

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