Hopanoid inventory of Rhodoplanes spp.

Hopanoids are pentacyclic triterpenoid lipids and are important for bacterial membrane stability and functioning. These pentacyclic triterpenoids of hopane series are biomarkers for eubacteria and can be used as chemotaxonomic markers. Anoxygenic phototrophic bacteria are good producers of hopanoids, and their inventory to date is restricted to a few members. Rhodoplanes spp. are phototrophic prokaryotes which grow and thrive in subsurface and sediment environments. A study on the diversity of hopanoids of several species of Rhodoplanes revealed a rich diversity of hopanoids with carbon length of C30/C31 and C35. Hop-22(29)-ene (II), diplopterol (V), tetrahymanol (VII), 2-methyldiplopterol (VI), 2-methyltetrahymanol (VIII), bacteriohopanetetrol (IX), bacteriohopaneaminotriol (X) and bacteriohopanepolyols [BHP-492 (XIII), BHP-550 (XIV), BHP-508 (XII)] are the major hopanoids of the genus Rhodoplanes. Tetrahymanol (VII) content is high (38-60 %) among all the members, except for Rhodoplanes elegans. Hopanoid fingerprints allowed differentiation of species of the genus Rhodoplanes. Statistical analyses also indicate hopanoids as good chemotaxonomic markers to distinguish species of the genus Rhodoplanes.

Salinicoccus halitifaciens sp. nov., a novel bacterium participating in halite formation.

Strain JC90(T) was isolated from a soda lake in Lonar, India. Strain JC90(T) maintains its external pH to 8.5 and participates in halite formation. Based on 16S rRNA gene sequence similarity studies, strain JC90(T) was found to belong to the genus Salinicoccus and is most closely related to "Salinicoccus kekensis" K164(T) (99.3 %), Salinicoccus alkaliphilus T8(T) (98.4 %) and other members of the genus Salinicoccus (<96.5 %). However Strain JC90(T) is <36 % related (based on DNA-DNA hybridization) with the type strains of "S. kekensis" K164(T) and S. alkaliphilus T8(T). The DNA G+C content of strain JC90(T) was determined to be 46 mol %. The cell-wall amino acids were identified as lysine and glycine. Polar lipids were found to include diphosphatidylglycerol, phosphatidylglycerol, phosphatidyl ethanolamine, an unidentified glycolipid and unidentified lipids (L1,2). Major hopanoids of strain JC90(T) were determined to be bacterial hopane derivatives (BHD1,2), diplopterol, diploptene and two unidentified hopanoids (UH1,2). The predominant isoprenoid quinone was identified as menaquinone (MK-6). Anteiso-C15:0 was determined to be the predominant fatty acid and significant proportions of iso-C14:0, C14:0, iso-C15:0, C16:0, iso-C16:0, iso-C17:0, anteiso-C17:0 and C18:02OH were also detected. The results of physiological and biochemical tests support the molecular evidence and allowed a clear phenotypic differentiation of strain JC90(T) from all other members of the genus Salinicoccus. Strain JC90(T) is therefore considered to represent a novel species, for which the name Salinicoccus halitifaciens sp. nov. is proposed. The type strain is JC90(T) (=KCTC 13894(T) =DSM 25286(T)).