Maribacter antarcticus sp. nov., a novel psychrophilic bacterium isolated from a culture of the Antarctic green alga Pyramimonas gelidicola

Abstract

A psychrophilic, Gram-negative, dark-orange-pigmented bacterium, designated CL-AP4T, was isolated from a culture of a green alga Pyramimonas gelidicola from the Antarctic ocean. Strain CL-AP4T grew optimally at temperature of 10°C, in the presence of 3？4% sea salts and pH 8. The 16S rRNA gene sequence analysis revealed that strain CL-AP4T belonged to the family Flavobacteriaceae with Maribacter arcticus as its closest relative (similarity of 97.2%). The following chemotaxonomic characteristics support the affiliation of strain CL-AP4 with the members of the genus Maribacter: iso-C15:0 (17.2%), isoG-C15:1 (16.8%) and iso-C17:0 3-OH (14.9%) as the dominant fatty acids. MK-6 is the major menaquinone. DNA G+C content is 37.1 mol%. Phylogenetic analyses of the 16S rRNA gene sequences showed that strain CL-AP4T formed a robust clade with M. arcticus. However, the DNA-DNA relatedness between CL-AP4T and M. arcticus was 10%, suggesting that they are genomically distinct species. In addition, strain CL-AP4T differed phenotypically from M. arcticus by optimum growth temperature, hydrolysis of starch, Tweens 40 and 80 and productions of certain enzymes. On the basis of the results of the polyphasic analysis, strain CL-AP4T was classified in the genus Maribacter as a novel species, for which the name Maribacter antarcticus sp. nov. is proposed. The type strain is CL-AP4T (= KCCM 90069T = JCM 15445T).