Oleispira antarctica gen. nov., sp. nov., a novel hydrocarbonoclastic marine bacterium isolated from Antarctic coastal sea water

TLDR

The authors propose a new genus and species, Oleispira antarctica, based on ecophysiological traits, G+C content, 16S rRNA sequences, and fatty acid profiles. They characterized two Antarctic marine strains, RB‑8T and RB‑9, by determining their taxonomic traits, ecophysiology, G+C content, 16S rRNA gene sequences, and fatty acid composition. The psychrophilic, aerobic, Gram‑negative strains grow only with NaCl (optimal 3–5 % w/v), possess monounsaturated straight‑chain fatty acids, synthesize eicosapentaenoic acid at low temperatures, have 41–42 % G+C DNA, form a distinct γ‑Proteobacteria lineage (<89.6 % 16S identity), and preferentially degrade aliphatic hydrocarbons, with strain RB‑8T designated as the type.

Abstract

The taxonomic characteristics of two bacterial strains, RB-8T and RB-9, isolated from hydrocarbon-degrading enrichment cultures obtained from Antarctic coastal marine environments (Rod Bay, Ross Sea), were determined. These bacteria were psychrophilic, aerobic and Gram-negative with polar flagella. Growth was not observed in the absence of NaCl, occurred only at concentrations of Na+ above 20 mM and was optimal at an NaCl concentration of 3–5 % (w/v). The major cellular fatty acids were monounsaturated straight-chain fatty acids. The strains were able to synthesize the polyunsaturated fatty acid eicosapentaenoic acid (20 : 5ω3) at low temperatures. The DNA G+C contents were 41–42 mol%. The strains formed a distinct phyletic line within the γ-Proteobacteria, with less than 89·6 % sequence identity to their closest relatives within the Bacteria with validly published names. Both isolates exhibited a restricted substrate profile, with a preference for aliphatic hydrocarbons, that is typical of marine hydrocarbonoclastic micro-organisms such as Alcanivorax, Marinobacter and Oleiphilus. On the basis of ecophysiological properties, G+C content, 16S rRNA gene sequences and fatty acid composition, a novel genus and species within the γ-Proteobacteria are proposed, Oleispira antarctica gen. nov., sp. nov. nov.; strain RB-8T (=DSM 14852T=LMG 21398T) is the type strain.