Thiomonas bhubaneswarensis sp. nov., an obligately mixotrophic, moderately thermophilic, thiosulfate-oxidizing bacterium

1 Department of Biotechnology, Institute of Life Sciences, Nalco Square, Bhubaneswar 751 023, India 2 Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India 3 Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA Correspondence Subrata K. Das subratkdas{at}hotmail.com A novel aerobic, obligately mixotrophic, moderately thermophilic, thiosulfate-oxidizing bacterium, S10 T , was isolated from hot-spring sediment samples collected from Atri, Bhubaneswar, India. The cells of this isolate stained Gram-negative and were strictly aerobic, non-sporulating, rod-shaped and motile with a single polar flagellum. Strain S10 T was positive for oxidase and catalase activities. It was capable of utilizing thiosulfate under mixotrophic growth conditions. Mixotrophic growth was observed at pH 6.0–8.5 and 25–45 °C; optimum growth occurred at pH 7.5–8.0 and 30–37 °C. The major cellular fatty acids were C 12 : 0 3-OH, C 16 : 1 7 c , C 16 : 0 , C 17 : 0 cyclo, C 18 : 1 7 c and C 19 : 0 cyclo 8 c . The DNA G+C content of strain S10 T was 64.8 mol%. 16S rRNA gene sequence analysis indicated that the bacterium clustered within the radiation of the genus Thiomonas and showed 98.0 % similarity with Thiomonas perometabolis ATCC 23370 T and Thiomonas intermedia ATCC 15466 T . However, DNA–DNA reassociation values of strain S10 T with Thiomonas perometabolis JCM 20426 T and Thiomonas intermedia JCM 20425 T , its nearest phylogenetic relatives, were 46 and 39 %, respectively. On the basis of phenotypic, physiological and chemotaxonomic properties, 16S rRNA gene sequence analysis and DNA–DNA reassociation studies, it is proposed that strain S10 T represents a novel species of the genus Thiomonas , Thiomonas bhubaneswarensis sp. nov.; the type strain is S10 T (=DSM 18181 T =JCM 14806 T ). The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain S10 T is DQ092334 .