Deinococcus indicus sp. nov., an arsenic-resistant bacterium from an aquifer in West Bengal, India

Abstract

An arsenic- and radiation-resistant bacterium, strain Wt/1a^T, was isolated from water from an arsenic-contaminated aquifer located in the Chakdah district of West Bengal, India. The bacterium stains Gram-negative and is rod-shaped, non-motile, non-sporulating and red-pigmented. Cell-wall peptidoglycan contains ornithine as the diamino acid, MK-8 is the major menaquinone, C_15:1 and C_16:1 are the major fatty acids and the DNA G+C content of the organism is 65·8 mol%. Based on these phenotypic and chemotaxonomic characteristics, strain Wt/1a^T was identified as a member of the genus Deinococcus. Strain Wt/1a^T exhibited maximum 16S rRNA gene sequence similarity (95%) with Deinococcus grandis; however, strain Wt/1a^T exhibited only 14% similarity to D. grandis IAM 13005^T at the DNA-DNA level. Furthermore, strain Wt/1a^T (compared to D. grandis IAM 13005^T) is more resistant to arsenate and arsenite, is positive for arginine dihydrolase, utilizes a number of carbon sources and exhibits quantitative differences in fatty acid composition and qualitative differences in lipid composition. Strain Wt/1a^T is identified as a novel species of the genus Deinococcus, for which the name Deinococcus indicus sp. nov. is proposed. The type strain of Deinococcus indicus is Wt/1a^T (=MTCC 4913^T=DSM 15307^T).