Methanosaeta harundinacea sp. nov., a novel acetate-scavenging methanogen isolated from a UASB reactor

Abstract

Two methanogenic strains, 8AcT and 6Ac, were isolated from an upflow anaerobic sludge blanket reactor treating beer-manufacture wastewater in Beijing, China. Cells of strains 8Ac T and 6Acwere rod-shaped (0?8-1?063-5 mm) and non-motile, occurring singly or in pairs; however, at high cell density the cells were arranged in long chains within a common sheath. The two strains used acetate exclusively for growth and methane production. The specific growth rate of strain 8AcT was 0?030 h "1 when growing in acetate (20 mM) at 37 6C. The temperature range for growth was 25-45 6C, with the fastest growth at 34-37 6C. The pH range for growth and methane production was 6?5-9?0, with the fastest growth at pH 7?2-7?6. The G+C content of genomic DNA of strain 8Ac T was 55?7 mol%. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that the novel strains clustered with Methanosaeta species; the 16S rRNA gene sequence similarities between strain 8Ac T and Methanosaeta concilii DSM 3013and 'Methanosaeta thermophila' DSM 6194 were 92?5 and 87?3 %, respectively. The sequence similarity levels of mcrA, the gene encoding the a-subunit of methyl-coenzyme M reductase, and of the deduced amino acids of mcrA, between strain 8Ac T and Methanosaeta concilii DSM 3671 T were 36 and 78?9 %, respectively. Based on the phylogenetic and phenotypic analyses, the novel species Methanosaeta harundinacea sp. nov. is proposed, with strain 8Ac T (=JCM 13211 T =CGMCC 1.5026 T ) as the type strain.Acetate is an important substrate for methanogenesis in anaerobic bioreactors and two-thirds or more of the methane produced in anaerobic bioreactors is derived from acetate (Zinder, 1993). All described acetate-using methanogens belong to the order Methanosarcinales. Among these, Methanosaeta species can be distinguished from members of the other genera by their exclusive use of acetate as a substrate for producing methane and by their rod-shaped cells, instead of coccoid or pseudosarcinal cells such as those of Methanosarcina species. In addition, in contrast to Methanosarcina species, Methanosaeta strains are favoured in environments with low concentrations of acetate (Huser et al., 1982). To date, only two species have been described in the genus Methanosaeta, Methanosaeta concilii (Patel & Sprott, 1990) and 'Methanosaeta thermophila ' (Kamagata et al., 1992;Boone & Kamagata, 1998), although investigations based on culture-independent approaches have indicated that Methanosaeta strains occur widely (Lueders et al., 2001; Zengler et al., 1999). Ultrastructural analysis of granules from upflow anaerobic sludge blanket (UASB) reactors using scanning and transmission electron microscopy has also shown numerous Methanosaeta-like cells, implying that they could play important roles in methanogenesis (Guiot et al., 1992;MacLeod et al., 1990; GonzalezGil et al., 2001).During a survey of the microbial community of a mesophilic methane-producing UASB reactor in Beijing, China, we isolated two strains of rod-shaped methanogens that produced meth...

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

“…For example, probe MMX1273 could not target M. harundinacea (single MM in targeted 16S rRNA sequence) and related clones (Figure 3; accession no. AB266892), which were recently isolated or obtained from UASB process treating beer-processing wastewater (Ma et al, 2006). Hence, further improvement of scissor probes for Methanosaetaceae group is necessary to better quantify their abundance in anaerobic environments.…”

Acyl homoserine lactone-based quorum sensing in a methanogenic archaeon

“…Methanogen strain and growth conditions M. harundinacea 6Ac was maintained in our laboratory and routinely cultured in a pre-reduced basal medium containing 50 mM sodium acetate, yeast extract (0.05%, w/v) and peptone (0.05%, w/v) as described previously (Doddema and Vogels, 1978;Ma et al, 2006). To promote the formation of filaments, the acetate in growing cultures was replenished up to three times with 50 mM sodium acetate.…”

“…We previously isolated an obligate aceticlastic methanogenic archaeon, Methanosaeta harundinacea 6Ac, from the up-flow anaerobic sludge bed granules in an anaerobic digester (Ma et al, 2006). Intriguingly, this methanogen shows a cell densitydependent cell assembly (as described below), making it a good model system for the study of quorum sensing behaviour in archaea.…”

Methermicoccus shengliensis gen. nov., sp. nov., a thermophilic, methylotrophic methanogen isolated from oil-production water, and proposal of Methermicoccaceae fam. nov.

“…Methanimicrococcus blatticola is unusual in the family because it requires both a methyl compound and H 2 , similar to members of the genus Methanosphaera (Sprenger et al, 2000). Members of the family Methanosaetaceae that ferment acetate as the sole source of energy include Methanosaeta concilii (Patel & Sprott, 1990), Methanothrix thermophila (Boone & Kamagata, 1998;Kamagata & Mikami, 1991) and Methanosaeta harundinacea (Ma et al, 2006). Work in our laboratory has focused on the study of anaerobes, especially methanogens, of petroleum reservoirs.…”