Cryobacterium tepidiphilum sp. nov., isolated from rhizosphere soil of lettuce (var. ramosa Hort.)

Abstract

A Gram-stain positive, aerobic, rod-shaped bacterium, designated strain NEAU-85T, was isolated from rhizosphere soil of lettuce and characterised using a polyphasic approach. Strain NEAU-85T was found to be catalase positive, motile and able to grow at between 10 and 30 °C. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain NEAU-85T belongs to the genus Cryobacterium and is closely related to the type strain Cryobacterium psychrotolerans JCM 13925T (98.5%) and also to Leifsonia kafniensis NCCB 100216T (97.6%). Multilocus sequence analysis using the concatenated gene sequences of the atpD, dnaK, recA, rpoB, sevY and ychF genes showed that strain NEAU-85T belongs to the genus Cryobacterium. The digital DNA–DNA hybridization values revealed that strain NEAU-85T is distinct from its close phylogenetic neighbour C. psychrotolerans. The menaquinones were identified as MK-10 and MK-11. The phospholipid profile was found to consist of diphosphatidylglycerol, phosphatidylglycerol, phospholipid, an unidentified glycolipid and an unidentified lipid. The major fatty acids were identified as anteiso-C15:0, anteiso-C15:1 and iso-C16:0. The genomic DNA G + C content of strain NEAU-85T was determined to be 68.9 mol%. The DNA–DNA hybridization value between them was less than 70%. On the basis of phenotypic, genotypic and phylogenetic data, strain NEAU-85T can be concluded to represent a novel species of the genus Cryobacterium, for which the name Cryobacterium tepidiphilum sp. nov. is proposed. The type strain is NEAU-85T (= CCTCC AA 2018035T = JCM 32545T).