Spirochaeta sphaeroplastigenens sp. nov., a halo-alkaliphilic, obligately anaerobic spirochaete isolated from soda lake Lonar

Abstract

Two helical-shaped bacteria (strains JC133Tand JC143), which stain Gram-negative, were isolated from an alkaline soda lake, Lonar, India. Both strains were obligate anaerobes, mesophilic and required halo-alkaline conditions for growth. Both strains were resistant to rifampicin and kanamycin, but sensitive to gentamicin, tetracycline, ampicillin and chloramphenicol. Both strains had phosphatidylglycerol (PG), diphosphotidylglycerol (DPG), glycolipid (GL) and four unidentified lipids (L1–4) as the major polar lipids. C18 : 1ω7cwas the predominant cellular fatty acid with significant proportions of C16 : 0, C18 : 1ω9c, C14 : 0, C18 : 0, C16 : 1ω5c, C18 : 1ω5cand C20 : 1ω9c. The DNA G+C contents of strain JC131Tand JC143 were 58.2 and 58.5 mol%, respectively, and the two strains showed DNA reassociation >85 % (based on DNA–DNA hybridization). Based on the 16S rRNA gene sequence analysis, both strains were identified as belonging to the genusSpirochaetawithSpirochaeta alkalicaZ-7491T(99.6 % sequence similarity),Spirochaeta americanaASpG1T(99 %) and other members of the genusSpirochaeta(<93 %) as their closest phylogenetic neighbours. However, strain JC133Tand JC143 displayed less than 53.5 % binding (based on DNA–DNA hybridization) withS. alkalicaZ-7491TandS. americanaASpG1T. On the basis of physiological, biochemical, chemotaxonomic and molecular properties, strains JC133Tand JC143 can be differentiated from other members of the genusSpirochaetaand represent a novel species of the genusSpirochaeta, for which the nameSpirochaeta sphaeroplastigenenssp. nov. is proposed. The type strain is JC133T( = KCTC 15220T = NBRC 109056T).