Clostridium huakuii sp. nov., an anaerobic, acetogenic bacterium isolated from methanogenic consortia

A Gram-staining-positive, spore-forming, obligately anaerobic, acetogenic bacterium, designated LAM1030T, was isolated from methanogenic consortia enriched from biogas slurry collected from the large-scale anaerobic digester of Modern Farming Corporation in Hebei Province, China. Cells of strain LAM1030T were motile, straight or spiral-rod-shaped. Strain LAM1030T could utilize glucose, fructose, maltose, galactose, lactose, sucrose, cellobiose, mannitol, pyruvate, succinic acid and tryptophan as the sole carbon source. Acetic acid, isovaleric acid and butanoic acid were the main products of glucose fermentation. Sodium sulfite was used as an electron acceptor. Growth of strain LAM1030T was completely inhibited by the addition of ampicillin, tetracycline, gentamicin or erythromycin at a concentration of 20 µg ml−1. The main polar lipids of strain LAM1030T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, 11 unknown glycolipids and two unknown phospholipids. No respiratory quinone was detected. The major fatty acids of strain LAM1030T were C16 : 0 (21.1 %), C14 : 0 (10.3 %), summed feature 9 (including C16:0 10-methyl and/or iso-C17:1 ω9c) (11.3% ), summed feature 3 (including C16:1 ω7c and/or C16:1 ω6c) (10.6% ) and iso-C15 : 0 (6.6 %). Analysis of the 16S rRNA gene sequence indicated that strain LAM1030T belonged to the genus Clostridium and was most closely related to Clostridium subterminale DSM 6970T, Clostridium thiosulfatireducens DSM 13105T and Clostridium sulfidigenes DSM 18982T, with 97.0, 96.9 and 96.8 % similarity, respectively. The G+C content of the genomic DNA of strain LAM1030T was 31.2±0.3 mol%. On the basis of its phenotypic, phylogenetic and chemotaxonomic characterization, strain LAM1030T is suggested to represent a novel species of the genus Clostridium , for which the name Clostridium huakuii sp. nov. is proposed. The type strain is LAM1030T ( = ACCC 00698T = JCM 19186T).