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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 8AcT and 6Ac were rod-shaped (0·8–1·0×3–5 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 8AcT was 0·030 h−1 when growing in acetate (20 mM) at 37 °C. The temperature range for growth was 25–45 °C, with the fastest growth at 34–37 °C. 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 8AcT 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 8AcT 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 8AcT and Methanosaeta concilii DSM 3671T were 36 and 78·9 %, respectively. Based on the phylogenetic and phenotypic analyses, the novel species Methanosaeta harundinacea sp. nov. is proposed, with strain 8AcT (=JCM 13211T=CGMCC 1.5026T) as the type strain.
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