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

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

Rubrivivax benzoatilyticus sp.nov., an aromatic hydrocarbon-degrading purple betaproteobacterium

A brown-coloured bacterium was isolated from photoheterotrophic (benzoate) enrichments of flooded paddy soil from Andhra Pradesh, India. On the basis of 16S rRNA gene sequence analysis, strain JA2(T) was shown to belong to the class Betaproteobacteria, related to Rubrivivax gelatinosus (99 % sequence similarity). Cells of strain JA2(T) are Gram-negative, motile rods with monopolar single flagella. The strain contained bacteriochlorophyll a and most probably the carotenoids spirilloxanthin and sphaeroidene, but did not have internal membrane structures. Intact cells had absorption maxima at 378, 488, 520, 590, 802 and 884 nm. No growth factors were required. Strain JA2(T) grew on benzoate, 2-aminobenzoate (anthranilate), 4-aminobenzoate, 4-hydroxybenzoate, phthalate, phenylalanine, trans-cinnamate, benzamide, salicylate, cyclohexanone, cyclohexanol and cyclohexane-2-carboxylate as carbon sources and/or electron donors. The DNA G+C content was 74.9 mol%. Based on DNA-DNA hybridization studies, 16S rRNA gene sequence analysis and morphological and physiological characteristics, strain JA2(T) is different from representatives of other photosynthetic species of the Betaproteobacteria and was recognised as representing a novel species, for which the name Rubrivivax benzoatilyticus sp. nov. is proposed. The type strain is JA2(T) (=ATCC BAA-35(T)=JCM 13220(T)=MTCC 7087(T))

Rhodovulum marinum sp. nov., a novel phototrophic purple non-sulfur alphaproteobacterium from marine tides of Visakhapatnam, India

A yellowish-brown bacterium was isolated from enrichment cultures inoculated with seawater samples from the eastern coast of India (Visakhapatnam) under photoheterotrophic conditions. Enrichment and isolation in a medium containing 2 % NaCl (w/v) yielded strain JA128T, which has ovoid to rod-shaped cells, also forms chains and is non-motile. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA128T clusters with the Alphaproteobacteria and the sequence similarity with its closest relatives, Rhodovulum iodosum and Rhodovulum sulfidophilum, was 95 %. Strain JA128T contained vesicular intracytoplasmic membranes, bacteriochlorophyll a and carotenoids of the spheroidene series. Strain JA128T was mesophilic, slightly acidophilic, slightly halophilic and grew photoheterotrophically with a number of organic compounds as carbon source and electron donor. It was unable to grow photoautotrophically, chemoautotrophically or by fermentative modes. It did not utilize sulfide, thiosulfate or hydrogen as electron donors. Thiamine was required as a growth factor. Based on the 16S rRNA gene sequence analysis, morphological and physiological characteristics, strain JA128T was significantly different from other species of the genus Rhodovulum and was recognized as a novel species for which the name Rhodovulum marinum sp. nov. is proposed. The type strain is JA128T (=ATCC BAA 1215T=CCUG 52183T=JCM 13300T)

Selective enrichment of Green Sulfur Bacteria in the presence of 4- Amino benzenesulfonate (Sulfanilate)

A novel selective enrichment method is described for phototrophic green sulfur bacteria even in the presence of purple sulfur and purple nonsulfur bacteria using sulfanilate, which was discovered during efforts to selectively isolate sulfanilate-metabolizing anoxygenic phototrophic bacteria from marine habitats. Samples for these experiments were obtained from beaches, saltpans, subsurface mangrove soils, fish and prawn aquaculture ponds and backwaters of the East and West coasts of India. Photoorganoheterotrophic and photolithoautotrophic enrichments in the absence of sulfanilate predominantly yielded purple bacterial enrichments. In contrast, photolithoautotrophic enrichments in the presence of sulfanilate yielded green-colored enrichments from the same samples. Whole cell absorption spectra of the enrichment cultures revealed the presence of bacteriochlorophyll c and thus green phototrophic bacteria. Microscopic observation demonstrated the presence of sulfur globules outside the bacterial cells and the presence of non-motile cells, some of which had prosthecae. 16S rDNA sequences obtained from green sulfur bacterial strains isolated from enrichment cultures confirmed the presence of representatives of the green sulfur bacterial genera Prosthecochloris and Chlorobaculum. The selective pressure of sulfanilate exerted through inhibition of phototrophic purple sulfur bacteria was demonstrated by inhibition studies using the purple sulfur bacteria Marichromatium indicum JA100 and Marichromatium sp. JA120 (JCM 13533) and the green sulfur bacterium Prosthecochloris sp. JAGS6 (JCM 13299)