Description of ‘Candidatus Marispirochaeta associata’ and reclassification of Spirochaeta bajacaliforniensis, Spirochaeta smaragdinae and Spirochaeta sinaica to a new genus Sediminispirochaeta gen. nov. as Sediminispirochaeta bajacaliforniensis comb. nov., Sediminispirochaeta smaragdinae comb. nov. and Sediminispirochaeta sinaica comb. nov.

Strain JC231 was isolated from a coastal saline habitat of Gujarat and was identified based on 16S rRNA gene sequence analysis as a member belonging to the genus Spirochaeta and showed highest sequence similarity (<91 %) with Spirochaeta bajacaliforniensis DSM 16054T and other members of the family Spirochaetaceae. Intensive attempts to culture strain JC231 in pure culture have failed and were associated with only one species of a Desulfovibrio. However, presence of fosmidomycin inhibited the growth of Desulfovibrio sp. and strain JC231 was characterized in its presence. Strain JC231 was an obligate anaerobe, helical shaped and Gram-stain-negative with catalase and oxidase negative. Draft genome sequence analysis of strain JC231 indicated the full complement of genes for both 2-C-methyl-d-erythritol 4-phosphate and 3-hydroxy-3-methylglutaryl-CoA pathways of terpenogenesis. C14 : 0, iso-C15 : 0, C16 : 0, iso-C15 : 1H/C13 : 0 3OH and iso-C14 : 0 are the major (>5 %) fatty acids. Strain JC231 contains diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and six unidentified lipids (L1-L6). G+C content of strain JC231 was 55.7 mol%. Distinct morphological, physiological and genotypic differences from the previously described taxa support the classification of strain JC231 as a representative of a new genus and species in the family Spirochaetaceae, for which the name 'CandidatusMarispirochaeta associata' is proposed. Strain JC231 is deposited as a defined co-culture with Desulfovibrio sp. JC271 to DSMZ (DSM 29857) and KCTC (KCTC 15472). Based on phenotypic, genotypic and phylogenetic analyses, we also propose the reclassification of Spirochaeta bajacaliforniensis as Sediminispirochaeta bajacaliforniensis gen. nov., comb. nov., Spirochaeta smaragdinae as Sediminispirochaeta smaragdinae comb. nov. and Spirochaeta sinaica as Sediminispirochaeta sinaica comb. nov.