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

A psychrophilic, Gram-negative, dark orange-pigmented bacterium, designated CL-AP4(T), was isolated from a culture of the green alga Pyramimonas gelidicola obtained from the Southern Ocean. Strain CL-AP4(T) grew optimally at 10 degrees C, in the presence of 3-4 % sea salts and at pH 8. 16S rRNA gene sequence analysis revealed that strain CL-AP4(T) belonged to the family Flavobacteriaceae, with Maribacter arcticus KOPRI 20941(T) as its closest relative (97.2 % similarity). A number of chemotaxonomic characteristics supported affiliation of strain CL-AP4(T) with the genus Maribacter, i.e. iso-C(15 : 0) (17.2 %), iso-C(15 : 1) (16.8 %) and iso-C(17 : 0) 3-OH (14.9 %) were the dominant fatty acids, MK-6 was the major menaquinone and the DNA G+C content was 37.1 mol%. DNA-DNA relatedness between CL-AP4(T) and M. arcticus KOPRI 20941(T) was only 10 %, suggesting that they are genomically distinct species. In addition, strain CL-AP4(T) differed phenotypically from M. arcticus in its optimum growth temperature, its ability to hydrolyse starch, Tween 40 and Tween 80, and production of certain enzymes. On the basis of the results of the polyphasic analysis, strain CL-AP4(T) was classified in the genus Maribacter as belonging to a novel species, for which the name Maribacter antarcticus sp. nov. is proposed; the type strain is CL-AP4(T) (=KCCM 90069(T)=JCM 15445(T)).