Alcanivorax borkumensis gen. nov., sp. nov., a new, hydrocarbon-degrading and surfactant-producing marine bacterium

TLDR

The authors propose the new genus and species *Alcanivorax borkumensis* to encompass these hydrocarbon‑degrading, biosurfactant‑producing marine bacteria. Six heterotrophic strains were isolated from sea‑water/sediment samples near Borkum by screening enriched cultures with C14–C15 n‑alkanes as the sole carbon source. The isolates are Gram‑negative, aerobic rods that metabolize aliphatic hydrocarbons, volatile fatty acids, pyruvate and its methyl ether, produce novel glucose‑based glycolipids that reduce water surface tension from 72 to 29 mN m⁻¹, and 16S rRNA sequencing places them in the γ‑Proteobacteria, distinct from known species, with strain SK2⁰ designated as the type.

Abstract

During screening for biosurfactant-producing, n-alkane-degrading marine bacteria, six heterotrophic bacterial strains were isolated from enriched mixed cultures, obtained from sea water/sediment samples collected near the Isle of Borkum (North Sea), using Mihagol-S (C14,15-n-alkanes) as principal carbon source. These Gram-negative, aerobic, rod-shaped bacteria use a limited number of organic compounds, including aliphatic hydrocarbons, volatile fatty acids, and pyruvate and its methyl ether. During cultivation on n-alkanes as sole source of carbon and energy, all strains produced both extracellular and cell-bound surface-active glucose lipids which reduced the surface tension of water from 72 to 29 mNm-1(16). This novel class of glycolipids was found to be produced only by these strains. The 16S rRNA gene sequence analysis showed that these strains are all members of the γ-subclass of the Proteobacteria. Their phospholipid ester-linked fatty acid composition was shown to be similar to that of members of the genus Halomonas, although they did not demonstrate a close phylogenetic relationship to any previously described species. On the basis of the information summarized above, a new genus and species, Alcanivorax borkumensis, is described to include these bacteria. Strain SK2Tis the type strain of A. borkumensis.