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

Two methanogenic strains, 8Ac^T and 6Ac, were isolated from an upflow anaerobic sludge blanket reactor treating beer-manufacture wastewater in Beijing, China. Cells of strains 8Ac^T and 6Ac were rod-shaped (0·81·0x35 µm) 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 8Ac^T was 0·030 h¹ when growing in acetate (20 mM) at 37 °C. The temperature range for growth was 2545 °C, with the fastest growth at 3437 °C. The pH range for growth and methane production was 6·59·0, with the fastest growth at pH 7·27·6. 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 3013 and Methanosaeta thermophila DSM 6194 were 92·5 and 87·3 %, respectively. The sequence similarity levels of mcrA, the gene encoding the α-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.