Marichromatium bheemlicum sp. nov., a non-diazotrophic, photosynthetic gammaproteobacterium from a marine aquaculture pond

1 Bacterial Discovery Laboratory, Centre for Environment, Institute of Science and Technology, JNT University, Kukatpally, Hyderabad 500 085, India 2 Department of Plant Sciences, School of Life Sciences, University of Hyderabad, PO Central University, Hyderabad 500 046, India 3 Leibniz-Institut für Meereswissenschaften, IFM-GEOMAR, Marine Mikrobiologie, Düsternbrooker Weg 20, 24105 Kiel, Germany Correspondence Ch. Sasikala r449{at}sify.com A rod-shaped, phototrophic, purple sulfur bacterium, strain JA124 T , was isolated in pure culture from a marine aquaculture pond, located near Bhimunipatnam, in a medium that contained 3 % NaCl (w/v). Strain JA124 T is a Gram-negative, motile rod with a single polar flagellum. Strain JA124 T has a requirement for NaCl, with optimum growth at 1.5–8.5 %, and tolerates up to 11 % NaCl. Intracellular photosynthetic membranes are of the vesicular type. Bacteriochlorophyll a and probably carotenoids of the spirilloxanthin series are present as photosynthetic pigments. Strain JA124 T was able to utilize sulfide, sulfate, thiosulfate, sulfite, thioglycollate and cysteine as sulfur sources. Strain JA124 T was able to grow photolithoautotrophically, photolithoheterotrophically and photo-organoheterotrophically. Chemotrophic and fermentative growth could not be demonstrated. Strain JA124 T lacks diazotrophic growth and acetylene reduction activity. Pyridoxal phosphate is required for growth. During growth on reduced sulfur sources as electron donors, sulfur is deposited intermediately as a number of small granules within the cell. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA124 T clusters with species of the genus Marichromatium belonging to the class Gammaproteobacteria . The highest sequence similarities of strain JA124 T were found with the type strains of Marichromatium indicum (98 %), Marichromatium purpuratum (95 %) and Marichromatium gracile (93 %). However, DNA–DNA hybridization with Marichromatium indicum DSM 15907 T revealed relatedness of only 65 % with strain JA124 T . The DNA base composition of strain JA124 T was 67 mol% G+C (by HPLC). Based on 16S rRNA gene sequence analysis, morphological and physiological characteristics and DNA–DNA hybridization studies, strain JA124 T (=ATCC BAA-1316 T =JCM 13911 T ) is sufficiently different from other Marichromatium species to merit its description as the type strain of a novel species, Marichromatium bheemlicum sp. nov. The GenBank/EMBL