Clostridium beihaiense sp. nov., an anaerobic bacterium isolated from activated sludge.

A Gram-positive, strictly anaerobic, rod-shaped bacterium, designated YB-7, was isolated from activated sludge of an anaerobic baffled reactor pond in Weizhou terminal wastewater treatment plant, Beihai, Guangxi, China. Strain YB-7 grew at pH 5.0-12.0 (optimum, pH 7.0), 20-45 °C (37 °C) and NaCl concentration of 0-5 % w/v (optimum, 5 %). 16S rRNA gene sequence analysis results showed that strain YB-7 belonged to the genus Clostridium and it was most closely related to Clostridium tetanomorphum DSM 4474 (96.9 % similarity). The DNA-DNA relatedness of strain YB-7 to Clostridium tetanomorphum DSM 4474 was 47.4 %. The DNA G+C content of strain YB-7 was determined to be 32.3 mol%, and the predominant cellar fatty acid (>10 %) was C16 : 0. Polar lipids of strain YB-7 included diphosphatidylglycerol, phosphatidylethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, two unidentified aminophospholipids, two unidentified phospholipids and unidentified lipids. The results of this study supported the conclusion that strain YB-7 should be assigned to a new member of the genus Clostridium, for which the name Clostridium beihaiense sp. nov. is proposed. The type strain is YB-7 (=CICC 24109=KCTC 15555).