Chromobacterium indicum sp. nov., a Pigment-Producing Bacterium Isolated from Soil

A purple colony, designated as TRC1.1.SA was isolated from a tea garden soil sample. It was a Gram-negative, rod-shaped, non-spore-forming and motile bacterium. The strain TRC1.1.SA^T grew aerobically at temperatures 15-37 ℃ and pH levels 5.0-9.0. It showed both oxidase and catalase activity. The 16S rRNA gene sequence blast analysis revealed identity with the members of the genus Chromobacterium. The maximum identity was with the type strains of species Chromobacterium piscinae CCM 3329^T (99.8%), C. vaccinii MWU205^T (99.7%), and C. violaceum ATCC 12472^T (98.7%). However, the average nucleotide identity (ANI) of the genome sequence showed less than 96% similarity with all species of the genus Chromobacterium. Further, digital DNA-DNA hybridization (dDDH) revealed the highest identity of 63.4% with its phylogenetic relative C. piscinae CCM 3329^T. The G + C content of the strain was 63.9%. The major polar lipids identified were phosphatidylethanolamine (PE), diphosphatidylglycerol (DPG), and phosphoglyceraldehyde (PG). Fatty acid analysis showed C_16:0, C_16:1ω7c, C_17:0 cyclo, and C_18:1ω7c as the major fatty acids. RAST and antiSMASH analyses of the genome revealed the presence of a biosynthetic gene cluster (BGC) involved in the production of violacein pigment, as observed for type species C. violaceum ATCC 12472^T. Considering the phenotypic differences and genomic identity, strain TRC1.1.SA^T is assigned as a novel species of the genus Chromobacterium, for which the name Chromobacterium indicum is proposed. The type strain of prospective species is designated as TRC1.1.SA^T (= MTCC 13391^T; JCM 36723^T; = KCTC 8324^T).