Characterization of Deinococcus sahariens sp. nov., a radiation-resistant bacterium isolated from a Saharan hot spring

An ultraviolet-radiation-resistant, Gram-positive, orange-pigmented, thermophilic and strictly aerobic cocci was isolated from Saharan water hot spring in Tunisia. The newly isolated bacterium, designated HAN-23^T, was identified based on polyphasic taxonomy including genotypic, phenotypic and chemotaxonomic characterization. Phylogenetic analysis based on 16S rRNA gene sequences placed this strain within Deinococcus genus. However, strain HAN-23^T is different from recognized species of the genus Deinococcus, showing less than 94.0% similarity values to its closest relatives. The predominant cellular fatty acids determined by gas chromatography were iso-C_15:0, iso-C_17:0 and iso C_17:1 ω9c. The major respiratory quinone was MK-8. The DNA G + C content was 66.9 mol%. DNA–DNA hybridization measurements revealed low DNA relatedness (6%) between the novel isolate and its closest neighbor, the type strain Deinococcus geothermalis DSM 11300. On the basis of the phenotypic, chemotaxonomic and phylogenetic data, strain HAN-23^T represents a novel species of the genus Deinococcus, for which the name Deinococcus sahariens sp. nov. is proposed, the type strain being HAN-23^T (=DSM 18496^T; LMG 23756^T).