# Oleispirillum naphthae gen. nov., sp. nov., a bacterium isolated from oil sludge, and proposal of Oleispirillaceae fam. nov

## TL;DR

Scientists discovered a new spiral-shaped bacterium from oil sludge and classified it as a new species, genus, and family.

## Contribution

The discovery and classification of a novel bacterium, Oleispirillum naphthae, and its placement in a new family Oleispirillaceae.

## Key findings

- Strain Y-M2T has unique growth conditions and fatty acid composition.
- The bacterium possesses a nitrogen-fixation cluster similar to methanogens.
- Phylogenetic and genomic analyses confirmed it belongs to a new family in Rhodospirillales.

## Abstract

A microaerophilic, Gram-negative, motile, and spiral-shaped bacterium, designated Y-M2T, was isolated from oil sludge of Shengli oil field. The optimal growth condition of strain Y-M2T was at 25 °C, pH 7.0, and in the absence of NaCl. The major polar lipid was phosphatidylethanolamine. The main cellular fatty acid was iso-C17  :  0 3-OH. It contained Q-9 and Q-10 as the predominant quinones. The DNA G+C content was 68.1 mol%. Strain Y-M2T showed the highest 16S rRNA gene sequence similarity to Telmatospirillum siberiense 26-4bT (91.1 %). Phylogenetic analyses based on 16S rRNA gene and genomes showed that strain Y-M2T formed a distinct cluster in the order Rhodospirillales. Genomic analysis showed that Y-M2T possesses a complete nitrogen-fixation cluster which is phylogenetically close to that of methanogene. The nif cluster, encompassing the nitrogenase genes, was found in every N2-fixing strain within the order Rhodospirillales. Phylogeny, phenotype, chemotaxonomy, and genomic results demonstrated that strain Y-M2T represents a novel species of a novel genus in a novel family Oleispirillaceae fam. nov. in the order Rhodospirillales, for which the name Oleispirillum naphthae gen. nov., sp. nov. was proposed. The type strain is Y-M2T (=CCAM 827T=JCM 34765T).