Cycloclasticus pugetii gen. nov., sp. nov., an Aromatic Hydrocarbon-Degrading Bacterium from Marine Sediments

TLDR

The closest known relatives of these Puget Sound bacteria are the methane‑oxidizing genera Methylobacter and Methylomonas, uncultured sulfur‑oxidizing symbionts from marine invertebrates, and clone FL5 from environmental 16S rRNA sequences. Based on these observations, the authors propose a new genus and species, Cycloclasticus pugetii, with strain PS‑1 as the type strain. Three heterotrophic strains were isolated from Puget Sound using biphenyl as the sole carbon source. The aerobic, gram‑negative, motile rods grow on aromatic hydrocarbons such as naphthalene, phenanthrene, anthracene, and toluene, belong to the γ‑Proteobacteria, do not metabolize methane or reduced sulfur compounds, and their 16S rRNA sequences are sufficiently divergent to justify a new genus, Cycloclasticus pugetii.

Abstract

Three heterotrophic bacterial strains were isolated from different locations in Puget Sound, Washington, by using biphenyl as the principal carbon source. These strains grow by using a limited number of organic compounds, including the aromatic hydrocarbons naphthalene, phenanthrene, anthracene, and toluene, as sole carbon sources. These aerobic, gram-negative rods are motile by means of single polar flagella. Their 16S rRNA sequences indicate that they are all members of the γ subdivision of the Proteobacteria. Their closest known relatives are the genera Methylobacter and Methylomonas (genera of methane-oxidizing bacteria), uncultured sulfur-oxidizing symbionts found in marine invertebrates, and clone FL5 containing 16S ribosomal DNA amplified from an environmental source. However, the Puget Sound bacteria do not use methane or methanol as a carbon source and do not oxidize reduced sulfur compounds. Furthermore, a 16S rRNA base similarity comparison revealed that these bacteria are sufficiently different from other bacteria to justify establishment of a new genus. On the basis of the information summarized above, we describe a new genus and species, Cycloclasticus pugetii, for these bacteria; strain PS-1 is the type strain of C. pugetii.