Pseudomonas neustonica sp. nov., isolated from the sea surface microlayer of the Ross Sea (Antarctica)

Gram- stain-negative, aerobic and rod-shaped bacterial strains, designated SSM26T and SSM44, were isolated from a sea surface microlayer sample from the Ross Sea, Antarctica. Analysis of the 16S rRNA gene sequences of strains SSM26T and SSM44 revealed a clear affiliation with the genus Pseudomonas. Based on the results of phylogenetic analysis, strains SSM26(T) and SSM44 showed the closest phylogenetic relationship with the species Pseudomonas sabulinigri KCTC 22137(T) with the 16S rRNA gene sequence similarity level of 98.5 %. Strains SSM26(T) and SSM44 grew optimally at 30 degrees C, pH 7.0-7.5 and 0.5- 10.0 % NaCl (w/v). The major cellular fatty acids were C-18: 1 omega 7c (31.3-34.9 %), C-16:0(15.5-20.2 %), summed feature 3 (C-16:1 omega 7c/ C-16:1 omega 6c; 19.5-25.4 %) and C-12:0 (6.0-9.3 %). The genomic DNA G+C content of each strain was 56.2 mol%. Genomic related-ness analyses based on the average nucleotide identity and the genome- to-genome distance showed that strains SSM26(T) and SSM44 constituted a single species that was clearly distinguishable from its phylogenetically close relatives. The combined phenotypic, chemotaxonomic, genomic and phylogenetic data also showed that strains SSM26(T) and SSM44 could be distin-guished from validly published members of the genus Pseudomonas. Thus, these strains should be classified as representing a novel species in the genus Pseudomonas, for which the name Pseudomonas neustonica sp. nov. is proposed with the type strain SSM26(T) (=KCCM 43193(T)=JCM 31284(T)=PAMC 28426(T)) and a sister strain SSM44 (=KCCM 43194=JCM 31285=PAMC 28427).