Discriminative signatures of methanotrophic communities according to the chemosynthetic habitats at the active mud volcano of the Canadian Beaufort Sea

Abstract

To obtain knowledge on the spatial variations of methanotrophic guilds along the methane flux regimes, we performed geochemical and microbiological analyses within a mud volcano (MV420) of the Canadian Beaufort Sea. Sediments were collected from visually discriminative chemosynthetic fields, bare of organisms (BO) with the naked eye, covered with bacterial mats (BM), or siboglinid tubeworms (ST) of MV420 and reference site. The methane flux decreased in the order of the BO, BM and ST sites. With the down core stratification of biogeochemical and microbial profiles within each site of MV420, lpid biomarker and 16S rRNA analyses revealed the spatial difference of aerobic methane oxidation (MOx)- and anaerobic methane oxidation (AOM)-related groups along the sites of MV420, which were distinctly different with the reference site. MOx-related bacteria, Methlyococcales dominated the surface layer of BO site whilst AOM-related archaea, mostly ANME-3 and sulfate reducing bacteria of Desulfobacteraceae and Desulfobulbaceae were predominant in the sediments of BO and ST sites. Accordingly, our results suggest that a niche diversification within this MV system has shaped distinct methanotrophic communities due to the availability of electron acceptors in association with varying degree of methane fluxes and bioirrigation activity.