Description of Gemmobacter fontiphilus sp. nov., isolated from a freshwater spring, reclassification of Catellibacterium nectariphilum as Gemmobacter nectariphilus comb. nov., Catellibacterium changlense as Gemmobacter changlensis comb. nov., Catellibacterium aquatile as Gemmobacter aquaticus nom. nov., Catellibacterium caeni as Gemmobacter caeni comb. nov., Catellibacterium nanjingense as Gemmobacter nanjingensis comb. nov., and emended description of the genus Gemmobacter and of Gemmobacter aquatilis

Abstract

A light-yellow-pigmented bacterial strain designated JS43T was isolated from a freshwater spring in Taiwan and was characterized using a polyphasic taxonomic approach. Cells of strain JS43T were Gram-negative-staining, facultatively anaerobic, rod-shaped, non-motile and non-spore-forming. Growth occurred at 10–30 °C (optimum, 25 °C), at pH 7.0–10.0 (optimum, pH 7.0–8.0) and with 0–0.5 % (w/v) NaCl (optimum, 0 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain JS43T was a member of the family Rhodobacteraceae of the class Alphaproteobacteria . Sequence similarities to type strains of the genera Gemmobacter and Catellibacterium were between 94.6 and 98.1 %. The highest sequence similarity was found with Gemmobacter aquatilis DSM 3857T. Strain JS43T contained C18 : 1ω7c as the predominant fatty acid (74.4 %). The major isoprenoid quinone was Q-10 and the DNA G+C content was 69.3 mol%. The polar lipid profile consisted of a mixture of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, two uncharacterized aminolipids and three uncharacterized phospholipids. The DNA–DNA relatedness values of strain JS43T with respect to the phylogenetically related Gemmobacter aquatilis DSM 3857T, Catellibacterium aquatile A1-9T and Catellibacterium caeni DCA-1T were less than 70 %. The taxonomic relationship between members of the genera Gemmobacter and Catellibacterium was clarified by means of a direct experimental comparison. Based on phylogenetic, chemotaxonomic and phenotypic data, we propose that all species currently classified in the genus Catellibacterium should be transferred to the genus Gemmobacter . The following new combinations are proposed: Catellibacterium nectariphilum is reclassified as Gemmobacter nectariphilus comb. nov. (type strain, AST4T = DSM 15620T = JCM 11959T = NBRC 100046T), Catellibacterium changlense as Gemmobacter changlensis comb. nov. (type strain, JA139T = CCUG 53722T = DSM 18774T = JCM 14338T), Catellibacterium aquatile as Gemmobacter aquaticus nom. nov. (type strain, A1-9T = CGMCC 1.7029T = NBRC 104254T), Catellibacterium caeni as Gemmobacter caeni comb. nov. (type strain, DCA-1T = CGMCC 1.7745T = DSM 21823T) and Catellibacterium nanjingense as Gemmobacter nanjingensis comb. nov. (type strain, Y12T = CCTCC AB 2010218T = KCTC 23298T). Emended descriptions of the genus Gemmobacter and of Gemmobacter aquatilis are also presented. Strain JS43T could be distinguished from recognized species of the genera Gemmobacter and Catellibacterium . It is suggested, on the basis of genotypic and phenotypic characteristics, that strain JS43T ( = BCRC 80082T = LMG 25376T) represents a novel species for which the name Gemmobacter fontiphilus is proposed.