Macroscopic Biofilms in Fracture-Dominated Sediment That Anaerobically Oxidize Methane

Abstract

Methane release from seafloor sediments is moderated, in part, by the anaerobic oxidation of methane (AOM) performed by consortia of archaea and bacteria. These consortia occur as isolated cells and aggregates within the sulfate-methane transition (SMT) of diffusion and seep-dominant environments. Here we report on a new SMT setting where the AOM consortium occurs as macroscopic pink to orange biofilms within subseafloor fractures. Biofilm samples recovered from the Indian and northeast Pacific Oceans had a cellular abundance of 10 7 to 10 8 cells cm ؊3 . This cell density is 2 to 3 orders of magnitude greater than that in the surrounding sediments. Sequencing of bacterial 16S rRNA genes indicated that the bacterial component is dominated by Deltaproteobacteria, candidate division WS3, and Chloroflexi, representing 46%, 15%, and 10% of clones, respectively. In addition, major archaeal taxa found in the biofilm were related to the ANME-1 clade, Thermoplasmatales, and Desulfurococcales, representing 73%, 11%, and 10% of archaeal clones, respectively. The sequences of all major taxa were similar to sequences previously reported from cold seep environments. PhyloChip microarray analysis detected all bacterial phyla identified by the clone library plus an additional 44 phyla. However, sequencing detected more archaea than the PhyloChip within the phyla of Methanosarcinales and Desulfurococcales. The stable carbon isotope composition of the biofilm from the SMT (؊35 to ؊43‰) suggests that the production of the biofilm is associated with AOM. These biofilms are a novel, but apparently widespread, aggregation of cells represented by the ANME-1 clade that occur in methane-rich marine sediments.

Data report: microbial diversity in sediment near Grizzly Bare Seamount in Holes U1363B and U1363G

“…Similar to the samples described above, candidate bacterial phyla BHI80-139 and JS1 and lineages within the phylum Chloroflexi (i.e., Napoli-4B-65, Sh765B-AG-111, and vadinBA26) were shared between these samples, and all groups were phylogenetically related to gene clones that have previously been identified from marine sediment (e.g., Li et al, 1999;Reed et al, 2002;Newberry et al, 2004;Inagaki et al, 2006;Takeuchi et al, 2009;Briggs et al, 2011;Durbin and Teske, 2011;Hoshino et al, 2011). Candidate bacterial phylum JS1 formed the most abundant group detected (3 of 17 clones) in the near-surface squeeze cake sample from Hole U1363G (Fig.…”

“…F4A). Candidate bacterial phylum JS1 formed the most abundant group detected in the surface raw sediment Sample 1363B1H1_RS (7 of 19 clones), where it was also most closely related to environmental gene clones recovered from other samples described here and in marine sediment worldwide (e.g., Li et al, 1999;Newberry et al, 2004;Briggs et al, 2011) (Fig. F4B).…”

Anaerobic methane oxidation in low-organic content methane seep sediments

“…2b; 11 from Riedel et al, 2006b; 1 from Briggs et al, 2011; and 7 from this study), only Core 5 from this study contained methane near the sediment-seawater interface. Thus, despite a large accumulation of gas and gas hydrate within meters of the seafloor (dashed grey line in Fig.…”

“…(b) Coring locations from PGC01-03 ( ) and PGC02-08 ( ). Other piston cores taken in the area of Bullseye vent from previous studies are shown as black circles (Novosel et al, 2005;Riedel et al, 2006b) and black triangles (Briggs et al, 2011). The solid black line outlines the seafloor depression that defines the seep (Thomas et al, 2009).…”

A Generalized Model for Complex Wastewater Treatment with Simultaneous Bioenergy Production Using the Microbial Electrochemical Cell

“…4b) decrease from interface to the anode surface. Moreover, as it has been proved by experiments [45,46] the major biofilm microorganisms are electrogens and for this simulation the mean value of electrogens to methanogens ratio is 5.94. The biofilm thickness varied dynamically from 11 micron to 14.6 micron over time (Fig.…”