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 SSM26^T and SSM44, were isolated from a sea surface microlayer sample from the Ross Sea, Antarctica. Analysis of the 16S rRNA gene sequences of strains SSM26^T 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 °C, pH 7.0–7.5 and 0.5– 10.0 % NaCl (w/v). The major cellular fatty acids were C_{18: 1} ω7c (31.3–34.9%), C_{16: 0} (15.5–20.2%), summed feature 3 (C_{16: 1} ω7c/ C_{16: 1} ω6c; 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 relatedness 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 distinguished 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).