RESUMO
Two helical-shaped bacteria (strains JC133(T) and 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. C18:1ω7c was the predominant cellular fatty acid with significant proportions of C16:0, C18:1ω9c, C14:0, C18:0, C16:1ω5c, C18:1ω5c and C20:1ω9c. The DNA G+C contents of strain JC131(T) and 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 genus Spirochaeta with Spirochaeta alkalica Z-7491(T) (99.6% sequence similarity), Spirochaeta americana ASpG1(T) (99 %) and other members of the genus Spirochaeta (<93%) as their closest phylogenetic neighbours. However, strain JC133(T) and JC143 displayed less than 53.5 % binding (based on DNA-DNA hybridization) with S. alkalica Z-7491(T) and S. americana ASpG1(T). On the basis of physiological, biochemical, chemotaxonomic and molecular properties, strains JC133(T) and JC143 can be differentiated from other members of the genus Spirochaeta and represent a novel species of the genus Spirochaeta, for which the name Spirochaeta sphaeroplastigenens sp. nov. is proposed. The type strain is JC133(T) ( = KCTC 15220(T) = NBRC 109056(T)).
