Isolation of a novel acidiphilic methanogen from an acidic peat bog

Abstract

Acidic peatlands are among the largest natural sources of atmospheric methane and harbour a large diversity of methanogenic Archaea. Despite the ubiquity of methanogens in these peatlands, indigenous methanogens capable of growth at acidic pH values have resisted culture and isolation; these recalcitrant methanogens include members of an uncultured family-level clade in the Methanomicrobiales prevalent in many acidic peat bogs in the Northern Hemisphere. However, we recently succeeded in obtaining a mixed enrichment culture of a member of this clade. Here we describe its isolation and initial characterization. We demonstrate that the optimum pH for methanogenesis by this organism is lower than that of any previously described methanogen.

Trophic status impacts both the magnitude and stable carbon isotope composition of methane flux from peatlands

“…Equally plausible is that acidiphilic or acid tolerant aceticlastic methanogens are absent from bogs or may not exist. The most acid tolerant methanogen isolated to date from an ombrogenous mire was a hydrogenotroph belonging to the order Methanomicrobiales [Bräuer et al, 2006]. Under in situ conditions mixed populations of peatland methanogens have a broader pH response and are able to function at lower pH than this isolate but a predominance of H 2 /CO 2 methanogens in high latitude ombrogenous mires appears to be more common than within other types of freshwater systems.…”

Methanogens in Human Health and Disease

“…Although some archaea, such as the halophiles and thermophiles, are restricted to extreme environments, the methanogens are widespread and are found in nearly every habitat in which anaerobic biodegradation of organic compounds occurs, including the human and animal intestinal tracts ( 4,5 ), freshwater and marine sediments, and anaerobic waste digesters ( 4 ). Acidophilic methanogens are ubiquitous in peatlands, which are among the largest natural sources of atmospheric methane ( 6 There is growing evidence that host / microbial interactions within the gut can have a profound impact on human health and disease; in fact, the intestinal microfl ora have been shown to infl uence the innate physiology, biochemistry, immunology, maturation of the vasculature, and gene expression in a host. Although most research has focused on gut bacteria, current evidence suggests that the Archaea -an ancient domain of single-celled organisms -are resident within the gut in high numbers, and have direct and indirect effects on the host.…”

Quantitative detection of culturable methanogenic archaea abundance in anaerobic treatment systems using the sequence-specific rRNA cleavage method

“…Methane-producing archaea (methanogens) are known to proliferate in natural anaerobic ecosystems (Brauer et al, 2006;Mehta and Baross, 2006;Miyata et al, 2007;Sakai et al, 2007;Nunoura et al, 2008) and anaerobic biological systems , where external electron accepters (for example, oxygen, sulfate or ferric iron) other than carbon dioxide are relatively limited. These methanogens closely interact with anaerobic syntrophs (that is, fermentative heterotrophs and proton-reducing bacteria) by converting important intermediates such as hydrogen, formate and acetate, which are derived from the breakdown of complex organic matter, to methane and carbon dioxide (Schink, 1997;Hattori, 2008).…”