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 SSM26T and SSM44 showed the closest phylogenetic relationship with the species Pseudomonas sabulinigri KCTC 22137T with the 16S rRNA gene sequence similarity level of 98.5 %. Strains SSM26T 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 C18 : 1 ω7c (31.3-34.9 %), C16 : 0 (15.5-20.2 %), summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c; 19.5-25.4 %) and C12 : 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 SSM26T 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 SSM26T 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 SSM26T (=KCCM 43193T=JCM 31284T=PAMC 28426T) and a sister strain SSM44 (=KCCM 43194=JCM 31285=PAMC 28427).

Shewanella psychromarinicola sp. nov., a psychrophilic bacterium isolated from pelagic sediment of the Ross Sea (Antarctica), and reclassification of Shewanella arctica Kim et al. 2012 as a later heterotypic synonym of Shewanella frigidimarina Bowman et al. 1997.

Two Gram-stain-negative, rod-shaped, facultatively anaerobic, iron-reducing bacterial strains, designated M2T and R106, were isolated from pelagic surface-sediment of the Ross Sea, Antarctica. The 16S rRNA gene sequence analysis revealed that strains M2T and R106 were affiliated to the genus Shewanellaand formed a distinct subline in a robust clade encompassing Shewanella vesiculosa, Shewanella livingstonensis, Shewanella arcticaand Shewanella frigidimarinawith a range of sequence similarities of 98.1-98.9 %. Overall genome relatedness indices indicated that M2T and R106 represented a single genomic species, which was clearly distinguishable from the phylogenetically close relatives with lower values of species delineation thresholds. Cells of M2T grew optimally at 10-15 °C and pH 6.5 in the presence of 3.0-4.0 % (w/v) sea salts. The polar lipids of M2T comprised phosphatidylglycerol, phosphatidylethanolamine, two unidentified aminophospholipids, an unidentified aminolipid and an unidentified phospholipid. Quinones were Q-7, Q-8, MK-7 and MMK-7. The major cellular fatty acids (>10 %) were C16 : 1ω7c and/or C16 : 1ω6c, C16 : 0 and C17 : 1ω8c. The DNA G+C content was 42.2 mol%. On the basis of the phenotypic, phylogenetic, genomic and chemotaxonomic features, we propose the name Shewanellapsychromarinicola sp. nov. with the type strain M2T (=KCCM 43257T =JCM 32090T) and the reclassification of S. arcticaas a later heterotypic synonym of S. frigidimarina.

Pseudoalteromonas neustonica sp. nov., isolated from the sea surface microlayer of the Ross Sea (Antarctica), and emended description of the genus Pseudoalteromonas.

A Gram-stain-negative, facultatively anaerobic, rod-shaped and motile strain, designated PAMC 28425T, was isolated from a sea surface microlayer sample from the Ross Sea, Antarctica. Analysis of the 16S rRNA gene sequence of strain PAMC 28425T showed an affiliation with the genus Pseudoalteromonas. Phylogenetic analyses revealed that strain PAMC 28425T formed a clade with Pseudoalteromonas prydzensis MB8-11T and Pseudoalteromonas mariniglutinosaKMM 3635T with 16S rRNA gene sequence similarities of 98.3-98.6 %. Genomic relatedness analyses based on the average nucleotide identity and the genome-to-genome distance showed that strain PAMC 28425T is clearly distinguished from the phylogenetically close relatives. Cells of strain PAMC 28425T grew optimally at 25 °C and pH 7.5-8.5 in the presence of 1.0-3.0 % (w/v) sea salts. The major cellular fatty acids (>10 %) were C16 : 1ω6c and/or C16 : 1ω7c, C16 : 0, and C18 : 1ω6c and/or C18 : 1ω7c. The genomic DNA G+C content was 39.7 mol%. On the basis of the phylogenetic, genomic, chemotaxonomic and phenotypic data presented, we propose the name Pseudoalteromonas neustonica sp. nov. with the type strain PAMC 28425T (=KCCM 43187T=JCM 31286T).