Williamsia marianensis sp. nov., a novel actinomycete isolated from the Mariana Trench.

The taxonomic status of an actinomycete isolated from sediment collected from the Mariana Trench was established using a combination of genotypic and phenotypic data. Isolate MT8T had chemotaxonomic and morphological properties consistent with its classification in the genus Williamsia, and formed a distinct phyletic line in the 16S rRNA gene tree together with the type strain of Williamsia muralis. The isolate was readily distinguished from the latter, and from representatives of other Williamsia species, using DNA-DNA relatedness and phenotypic criteria. Predominant cellular fatty acids were oleic, palmitic and tuberculostearic acids and a hexadecenoic acid. The DNA G+C content was 65.2 mol%. It is apparent that the isolate belongs to a novel species of Williamsia. Strain MT8T (=DSM 44944T=NCIMB 14085T) was thus considered to be the type strain of a novel species in the genus Williamsia, for which the name Williamsia marianensis sp. nov. is proposed.