Geodermatophilus siccatus sp. nov., isolated from arid sand of the Saharan desert in Chad

A novel Gram-positive, aerobic, actinobacterial strain, CF6/1^T, was isolated in 2007 during environmental screening of arid desert soil in the Sahara near to Ourba, Chad. The isolate was found to grow best in a temperature range of 20–37 °C and at pH 6.0–8.5 and showed no NaCl tolerance, forming black-coloured and nearly circular colonies on GYM agar. Chemotaxonomic and molecular characteristics determined for the isolate match those previously described for members of the genus Geodermatophilus. The DNA G + C content of the novel strain was determined to be 74.9 mol %. The peptidoglycan was found to contain meso-diaminopimelic acid as the diagnostic diamino acid. The main phospholipids were determined to be phosphatidylethanolamine, phosphatidylinositol, phosphatidylcholine, diphosphatidylglycerol and traces of phosphatidylglycerol; MK-9(H₄) was identified as the dominant menaquinone and galactose as the diagnostic sugar. The major cellular fatty acids were found to be the branched-chain saturated acids iso-C_16:0 and iso-C_15:0, as well as C_17:1ω8c. The 16S rRNA gene sequence shows 97.5–97.9 % sequence identity with the four validly named or at least effectively published members of the genus: Geodermatophilus obscurus (97.5 %), Geodermatophilus arenarius (97.7 %), Geodermatophilus ruber (97.9 %) and Geodermatophilus nigrescens (97.9 %). Based on the results from this polyphasic taxonomic analysis and DNA–DNA hybridizations with all type strains of the genus, we propose that strain CF6/1^T represents a novel species, Geodermatophilus siccatus, with the type strain CF6/1^T = DSM 45419^T = CCUG 62765^T = MTCC 11414^T.