Thauera sinica sp. nov., a phenol derivative-degrading bacterium isolated from activated sludge.

A bacterial strain, K11, capable of degrading phenol derivatives was isolated from activated sludge of a sewage treatment plant in China. This strain, which can degrade more than ten phenol derivatives, was identified as a Gram-stain negative, rod-shaped, asporogenous, facultative anaerobic bacterium with a polar flagellum. The strain was found to grow in tryptic soy broth in the presence of 0-2.5% (w/v) NaCl (optimum 0-1%), at 4-43 °C (optimum 30-35 °C) and pH 4.5-10.5 (optimum 7.5-8). Comparative analysis of nearly full-length 16S rRNA gene sequences showed that this strain belongs to the genus Thauera. The 16S rRNA gene sequence was found to show high similarity (97.5%) to that of Thauera chlorobenzoica 3CB-1, with lesser similarity to other recognised Thauera strains. The G+C content of the DNA of the strain was determined to be 67.8 mol%. The DNA-DNA hybridization value between K11 and Thauera aromatica DSM6984 was 10.4 ± 4.5%. The genomic OrthoANI values of K11 with the other nine type strains of genus Thauera were less than 81.1%. Chemotaxonomic analysis of strain K11 revealed that Q-8 is the predominant quinone; the polar lipids contain phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and five uncharacterised lipids; the major cellular fatty acid was identified as summed feature 3 (C ω7c and/or iso-C 2-OH; 45.9%), followed by C (20.5%) and C ω7c (15.8%). Based on the phenotypic and phylogenetic evidence, DNA-DNA hybridisation, OrthoANI, chemotaxonomic analysis and results of the physiological and biochemical tests, a new species named Thauera sinica sp. nov. is proposed with strain K11 (= CGMCC 1.15731 = KACC 19216) designated as the type strain.