Marichromatium fluminis sp nov., a slightly alkaliphilic, phototrophic gammaproteobacterium isolated from river sediment

An anoxygenic, phototrophic gammaproteobacterium designated strain JA418(T) was isolated from a sediment sample collected from the Baitarani River, Orissa, India. The bacterium was a Gram-negative, motile rod with a single polar flagellum. Bacteriochlorophyll a and rhodopin were the major photosynthetic pigments. The organism grew best at slightly alkaline pH (8-8.5) and lacked chemotrophic growth. The major fatty acids were C-16:0, C-16:1 omega 7c/C-16:1 omega 6c and C-18:1 omega 7c. A phylogenetic tree based on 16S rRNA gene sequence analysis showed that strain JA418(T) clusters with species of the genus Marichromatium belonging to the class Gammaproteobacteria. The highest 16S rRNA gene sequence similarities of strain JA418(T) were found with the type strains of Marichromatium gracile (95.9 %), Marichromatium indicum (95.6 %), Marichromatium purpuratum (95.5%) and Marichromatium bheemlicum (95.6%). The DNA base composition of strain JA418(T) was 71.4 mol% G+C (by HPLC). Based on the 16S rRNA gene sequence analysis and physiological and chemotaxonomic characteristics, strain JA418(T) is sufficiently different, from other Marichromatium species to merit the description of a novel species, Marichromatium fluminis sp. nov., to accommodate it. The type strain is JA418(T) (=KCTC 5717(T) =NBRC 105221(T)).