Thalassolituus oleivorans gen. nov., sp. nov., a novel marine bacterium that obligately utilizes hydrocarbons

Abstract

An aerobic, heterotrophic, Gram-negative, curved bacterial strain, designated MIL-1T, was isolated by extinction dilution from an n-tetradecane enrichment culture that was established from sea water/sediment samples collected in the harbour of Milazzo, Italy. In the primary enrichment, the isolate formed creamy-white, medium-sized colonies on the surface of the agar. The isolate did not grow in the absence of NaCl; growth was optimal at 2.7% NaCl. Only a narrow spectrum of organic compounds, including aliphatic hydrocarbons (C7-C20), their oxidized derivatives and acetate, were used as growth substrates. The isolate was not able to grow under denitrifying conditions. The DNA G+C content and genome size of strain MIL-1T were estimated to be 53.2 mol% and 2.2 Mbp, respectively. The major cellular and phospholipid fatty acids were palmitoleic, palmitic and oleic acids (33.5, 29.5 and 11.0% and 18, 32 and 31%, respectively). 3-hydroxy lauric acid was the only hydroxy fatty acid detected. Thirteen different compounds that belonged to two types of phospholipid (phosphatidylethylamine and phosphatidylglycerol) were identified. 16S rRNA gene sequence analysis revealed that this isolate represents a distinct phyletic lineage within the gamma-Proteobacteria and has about 94.4% sequence similarity to Oceanobacter kriegii (the closest bacterial species with a validly published name). The deduced protein sequence of the putative alkane hydrolase, AlkB, of strain MIL-1T is related to the corresponding enzymes of Alcanivorax borkumensis and Pseudomonas oleovorans (81 and 80% similarity, respectively). On the basis of the analyses performed, Thalassolituus oleivorans gen. nov., sp. nov. is described. Strain MIL-1T (=DSM 14913T=LMG 21420T) is the type and only strain of T. oleivorans.