The influence of ultramafic rocks on microbial communities at the Logatchev hydrothermal field, located 15°N on the Mid-Atlantic Ridge

Abstract

The ultramafic-hosted Logatchev hydrothermal field (LHF) on the Mid-Atlantic Ridge is characterized by high hydrogen and methane contents in the subseafloor, which support a specialized microbial community of phylogenetically diverse, hydrogen-oxidizing chemolithoautotrophs. We compared the prokaryotic communities of three sites located in the LHF and encountered a predominance of archaeal sequences affiliated with methanogenic Methanococcales at all three. However, the bacterial composition varied in accordance with differences in fluid chemistry between the three sites investigated. An increase in hydrogen seemed to coincide with the diversification of hydrogen-oxidizing bacteria. This might indicate that the host rock indirectly selects this specific group of bacteria. However, next to hydrogen availability further factors are evident (e.g. mixing of hot reduced hydrothermal fluids with cold oxygenated seawater), which have a significant impact on the distribution of microorganisms.

Culture dependent and independent analyses of 16S rRNA and ATP citrate lyase genes: a comparison of microbial communities from different black smoker chimneys on the Mid-Atlantic Ridge

“…While ANME-2 related 490 sequences have been previously recovered from marine hydrothermal sediments (Teske 491 et al 2002) and, more recently, one sequence was recovered from hydrothermal 492 emissions at Logatchev (Perner et al 2007), this is the first report of abundant ANME 493 sequences detected in a 16S rRNA gene library derived from a microbial community 494 associated with a black smoker. Interestingly, no sequences related to SRB were detected 495 in the Logatchev chimneys (Fig.…”

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“…OCCs incorporate highly reactive olivine-rich rocks that interact with seawater over a range of temperatures to produce both high-and low-temperature hydrothermal systems (Douville et al, 1997(Douville et al, , 2002Charlou et al, 1998Charlou et al, , 2002Sagalevich et al, 2000;Kelley et al, 2005;McCaig et al, 2007). Chemical exchange between the mantle and the hydrosphere supports abundant microbial communities in regions of focused fluid discharge in both types of systems (Schrenk et al, 2004;Takai et al, 2004;Nercessian et al, 2005;Brazelton et al, 2006;Campbell et al, 2006;Perner et al, 2007). However, it is unknown whether active microbial communities are also sustained by fluid-rock interaction in mantle-derived host rocks or in diffusely venting areas that surround focused-flow sites.…”

Microbial Ecology of the Dark Ocean above, at, and below the Seafloor

“…75,2011 MICROBIAL ECOLOGY OF THE DARK OCEAN 395 on May 11, 2018 by guest http://mmbr.asm.org/ and mantle rock-hosted hydrothermal sulfide chimney material has microbial communities that resemble, at the phylum level, those found on basalts (520, 581; Toner et al, submitted). Hydrothermal fluids, both vent fluids and plume waters, tend to be dominated by either Gammaproteobacteria or Epsilonproteobacteria (232,442,443,518). The phylum Acidobacteria, which is very common in soils (202), is rarely present in dark ocean habitats, with the notable exception of oxic surficial sediments (213,333,447,448,592).…”

“…Many hydrothermally influenced habitats have archaeal communities dominated by members of the phyla Archaeoglobus, Thermococcales, and Methanococcales (A/T/M in Fig. 8 and 13) (206,290,392,397,407,408,442,467,535,581). Basalt crust-related samples (135,163,232,354; B. N. Orcutt, K. J. Edwards, and E. Banning, unpublished data) have archaeal communities dominated by members of the MGI clade, which currently has only two cultivated representative genera, "Candidatus Nitrosopumilus" and Cenarchaeam (200,288).…”