Thalassospira lucentensis gen. nov., sp nov., a new marine member of the α-Proteobacteria

A novel bacterium from the Mediterranean Sea was isolated under oligotrophic conditions at in situ temperature after prolonged continuous culture. The isolates were initially characterized by partial 16S rRNA gene sequencing. Similarity searches of one of the isolates, QMT2(T), indicated high sequence identity to the well-characterized Rhodospirillum rubrum, [Aquaspirillum] itersonii and [oceanospirillum] pusillum micro-organisms, which are representatives of the alpha-subclass of the Proteobacteria. The highest level of similarity of the complete 16S rRNA gene with respect to these microorganisms was 89%. Features such as the low similarities of 16S rRNA of QMT2(T) with its phyllogenetically close neighbours, the distinct G+C content, and the differences in phenotypic features, including pigmentation, fatty acid composition, salt tolerance, the lack of bacteriochlorophyll a, and the capacity to use carbohydrates as carbon sources, are indicative of the novel nature of the isolate QMT2(T) among the alpha-Proteobacteria. This report describes the classification of strain QMT2(T) (= DSM 14000(T) = CECT 5390(T)) as a new genus and species, Thalassospira, lucentensis gen. nov, sp. nov., in the family Rhodospirillaceae.