Characterisation of a newly isolated member of a candidatus lineage, Marispirochaeta aestuarii gen. nov., sp. nov.

Metagenome analysis of coastal marine habitats of Gujarat, India indicated the presence of twelve novel putative lineages of spirochaetes. Out of which a strain designated JC444 representing a novel putative lineage seven was isolated and characterized based on a polyphasic taxonomic approach. Strain JC444 was helical, Gram-stain-negative, obligate anaerobe, catalase and oxidase negative. Strain JC444 was able to grow at 15-45 °C (optimum at 30-35 °C), pH 6.5-8.6 (optimum at 7.5-8.0) and 0.6-5 % (optimum at 1.5-2.0 %) of NaCl concentration. The major end products of glucose fermentation were acetate, formate, hydrogen and carbon dioxide. C14 : 0, iso-C15 : 0, C16 : 0, C18 : 0, iso-C15 : 1H/C13 : 03OH (summed feature 1), iso-C13 : 0, anteiso-C15 : 0 and iso-C17 : 0 were present as fatty acids. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and unidentified lipids (L1-4) were the polar lipids. G+C mol% of strain JC444 was 53.6 %. 16S rRNA gene sequence comparisons indicated that strain JC444 represents a member of the family Spirochaetaceae in the order Spirochaetales. Strain JC444 has a sequence similarity of 97.1 % with 'Candidatus Marispirochaeta associata' JC231 and <90.1 % with other members of the family Spirochaetaceae. Distinct morphological, physiological and genotypic differences from the previously described taxa support the classification of strain JC444 as a representative of a new genus and species in the family Spirochaetaceae, for which the name Marispirochaeta aestuarii gen. nov., sp. nov. is proposed. Type strain is JC444 (=KCTC 15554=DSM 103365).