Marichromatium indicum sp. nov., a novel purple sulfur gammaproteobacterium from mangrove soil of Goa, India.

A reddish-brown bacterium was isolated from photoheterotrophic enrichments of mangrove soil from the western coast of India, in a medium that contained 10 % (w/v) NaCl. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA100(T) clusters with species of the genus Marichromatium of the class 'Gammaproteobacteria'. Cells of strain JA100(T) are Gram-negative, motile rods with monopolar single flagella; they require NaCl, the optimum concentration being 1-4 %, and tolerate concentrations up to 13 %. The strain has vesicular internal membrane structures, bacteriochlorophyll a and, most probably, carotenoids of the spirilloxanthin series. No growth factors are required. A reduced sulfur source is required for growth, and, during growth on reduced sulfur sources as electron donors, sulfur is intermediately deposited as a single large granule within the cell. Strain JA100(T) could not grow at the expense of other tricarboxylic acid cycle intermediates, except malate. On the basis of 16S rRNA gene sequence analysis and its morphological and physiological characteristics, strain JA100(T) is sufficiently different from other Marichromatium species to justify its designation as a novel species, for which the name Marichromatium indicum sp. nov. is proposed. The type strain is JA100(T) (=DSM 15907(T)=ATCC BAA-741(T)=JCM 12653(T)).