Arcobacter anaerophilus sp. nov., isolated from an estuarine sediment and emended description of the genus Arcobacter

Two strains (JC83, JC84^T) of obligately anaerobic, H₂S-producing bacteria were isolated from estuarine sediment samples collected from Gangasagar, West Bengal, India. Cells were Gram-stain-negative, non-motile rods. Both strains were positive for oxidase, negative for catalase, hydrolysed casein, reduced nitrate and utilized citrate. Both strains grew chemoorganoheterotrophically with optimal pH of 7–8 (range 7–10) and at 30 °C (range 25–37 °C). C_16 : 1ω7c, C_18 : 1ω7c, C_16 : 0 and C_12 : 0 were the major fatty acids of both strains with minor amounts of C_14 : 0, C_12 : 0 3-OH and C_18 : 0. Polar lipids of both strains included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine, phosphatidylcholine, phosphatidylinositol, an unidentified aminolipid (AL2), an unidentified phospholipid (PL2) and an unidentified lipid (L3). MK-6 was the major respiratory quinone. The DNA G+C content of strains JC83 and JC84^T was 25.0 and 24.6 mol%, respectively. The strains showed DNA reassociation >85 % (86.0±0.5 %) (based on DNA–DNA hybridization). Based on 16S rRNA gene sequence analysis, both strains were identified as belonging to the family Campylobacteraceae of the class Epsilonproteobacteria with Arcobacter marinus CL-S1^T (95.4 % sequence similarity) as their closest phylogenetic neighbour. On the basis of morphological, physiological and chemotaxonomic characteristics as well as phylogenetic analysis, strains JC83 and JC84^T are considered to represent a novel species, for which the name Arcobacter anaerophilus sp. nov. is proposed. The type strain is JC84^T ( = KCTC 15071^T = MTCC 10956^T = DSM 24636^T). An emended description of the genus Arcobacter is provided.