Taxonomic study of the genus Tepidiphilus: transfer of Petrobacter succinatimandens to the genus Tepidiphilus as Tepidiphilus succinatimandens comb. nov., emended description of the genus Tepidiphilus and description of Tepidiphilus thermophilus sp. nov., isolated from a terrestrial hot spring

Abstract

Comparative phenotypic, chemotaxonomic and genetic analysis revealed significant similarities among strains of the genera Tepidiphilus and Petrobacter . Analysis of 16S rRNA gene sequences and DNA–DNA relatedness of the type strains Tepidiphilus margaritifer N2-214T and Petrobacter succinatimandens 4BONT showed sequence similarity of 98.9 % and less than 40 % relatedness, indicating that these strains represent different species of same genus. Both strains had phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and diphosphatidylglycerol as major polar lipids. Their fatty acid profiles were almost identical, with the predominant fatty acids C16 : 0, C17 : 0 cyclo and C19 : 0 cyclo ω8c. In view of this, we propose to transfer the member of the genus Petrobacter to the genus Tepidiphilus as Tepidiphilus succinatimandens comb. nov. and to emend the description of the genus Tepidiphilus . Further, a novel bacterium, strain JHK30T, was isolated from a terrestrial hot spring located at Jharkhand, India, and was identified following a polyphasic approach. Cells were non-sporulating, aerobic, Gram-stain-negative rods and motile by a single polar flagellum. Optimum temperature for growth was 50–55 °C at pH 6.5–7.0. 16S rRNA gene sequence analysis revealed 99.71 % similarity with P. succinatimandens 4BONT ( = DSM 15512T) and 98.71 % with T. margaritifer N2-214T ( = DSM 15129T). However, DNA–DNA relatedness of strain JHK30T with these two type strains was well below 70 %. The DNA G+C base composition was 66.1 mol%. Strain JHK30T represents a novel species of the genus Tepidiphilus for which the name Tepidiphilus thermophilus sp. nov. is proposed. The type strain is JHK30T ( = JCM 19170T = LMG 27587T= DSM 27220T).