Arcobacter pernae sp. nov. and Arcobacter rhizosphaerae sp. nov., two novel bacterial species isolated from the seagrass bed

Three bacterial strains, YIC-464 T (isolated from the intestinal tract of Perna mussels), YIC-310 T and YIC-80 (both isolated from rhizosphere soil), were obtained from a seagrass bed in Weihai, PR China. A polyphasic taxonomic study revealed that strains YIC-464 T and YIC-310 T represent two novel species within the genus Arcobacter . Phylogenetic analysis based on the 16S rRNA gene sequence showed that the closest relative of strains YIC-464 T , YIC-310 T and YIC-80 is Arcobacter roscoffensis KCTC 52423 T , with sequence similarities of 96.8, 98.0 and 98.0%, respectively. Furthermore, multilocus phylogenetic analysis based on five concatenated housekeeping genes ( atpA , gyrB , hsp60 , rpoB and gyrA ) demonstrated that strains YIC-464 T and YIC-310 T form distinct branches separate from other Arcobacter species. Average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between these strains and their closely related species were below the species delineation thresholds. Specifically, the ANI and dDDH values between YIC-464 T and YIC-310 T were 85.7 and 30.0%, respectively, while those between YIC-310 T and YIC-80 were 99.0 and 90.9%, respectively. These results confirm that strains YIC-464 T and YIC-310 T represent two novel species, whereas YIC-310 T and YIC-80 belong to the same species. Menaquinone-6 was identified as the sole respiratory quinone in all strains. The major fatty acids (>10.0%) included C 16 : 0 , summed feature 3 (C 16 : 1 ω7 c and/or C 16 : 1 ω6 c) and summed feature 8 (C 18 : 1 ω7 c and/or C 18 : 1 ω6 c). Phenotypic characterization further differentiated these strains from other species. Therefore, we propose two new species: Arcobacter pernae sp. nov. and Arcobacter rhizosphaerae sp. nov., with type strains YIC-464 T (=MCCC 1K09442 T =KCTC 102325 T ) and YIC-310 T (=MCCC 1K09441 T =KCTC 102324 T ), respectively.