Labilibaculum antarcticum sp. nov., a novel facultative anaerobic, psychrotorelant bacterium isolated from marine sediment of Antarctica.

A novel facultative anaerobic and facultative psychrophilic bacterium, designated SPP2T, was isolated from an Antarctic marine sediment. Cells of the isolate were observed to be long rods (0.5 × 5-10 μm), Gram-stain negative and to have gliding motility. For growth, the optimum NaCl concentration was found to be 2-3% and the optimum temperature to be 18-22 °C. Strain SPP2T cannot use sulfate and nitrate as electron acceptors in the presence of lactate. The G+C content of the genomic DNA was determined to be 36.0 mol%.. The major cellular fatty acids were identified as anteiso-C15:0 and iso-C15:0. MK-7 was found to be the predominant respiratory quinone. Phylogenetic analysis based on the 16S rRNA gene revealed that the novel strain belongs to the family Marinifilaceae and to be closely related to Labilibaculum manganireducens 59.10-2MT with 16S rRNA gene sequence identity of 98%. The OrthoANI and dDDH values between the genome sequences of strain SPP2T and its close relative were 84% and 27.3%, which are lower than the threshold values for species delineation. On the basis of phylogenetic and phenotypic characterisation, Labilibaculum antarcticum sp. nov. is proposed with the type strain SPP2T (= NBRC 111151T = CECT 9460T).