Clostridium indicum sp. nov., a novel anaerobic bacterium isolated from the sludge of an industrial effluent.

A strictly anaerobic bacterial strain, designated as PI-S10-A1B, was isolated from a sludge sample collected from an industrial effluent dump site at Hyderabad, India. Cells stained Gram-positive and contained terminal endospores. Optimal growth was observed at 30 °C and pH 7.0. It showed negative reactions to catalase and oxidase activities. Phylogenetic analysis of the 16S rRNA gene led to strain PI-S10-A1B ^T being assigned to the genus Clostridium. It displayed high sequence similarity to species of cluster XIVa including Clostridium amygdalinumBR-10 ^T (99.84 %), Clostridium saccharolyticum WM1 ^T (98.93 %) and Clostridium indolis DSM 755 ^T (98.31 %). It formed a coherent cluster with members of cluster XIVa. Despite high 16S rRNA gene sequence similarity, strain PI-S10-A1B ^T displayed only 25.3 % identity in DNA-DNA hybridization tests with C. amygdalinum BR-10 ^T . A draft genome exhibited low values for average nucleotide identity and in silico DNA-DNA hybridization with strains of cluster XIVa. The DNA G+C content was 42.3 mol%. Major lipids were phosphatidylglycerol and diphosphatidylglycerol, with an abundance of phosphoglycolipids. Further, analysis of the draft genome revealed genomic insights against functional aspects. Considering the phenotypic differences and low genomic identity with phylogenetic relatives, strain PI-S10-A1B ^T is concluded to represent a new species of the genus Clostridium, for which the name Clostridiumindicum sp. nov. is proposed with type strain PI-S10-A1B ^T (=MTCC 12282 ^T =DSM 24996 ^T =JCM 32788 ^T ).