Geodermatophilus telluris sp. nov., an actinomycete isolated from Saharan desert sand.

Abstract

A novel Gram-positive, multiloculated thalli-forming, aerobic, actinobacterial strain, CF9/1/1(T), was isolated in 2007 during environmental screening for xerophilic fungi in arid desert soil from the Sahara desert, Chad. The isolate grew best at a temperature range of 20-35 °C and at pH 6.0-8.5 and with 0-4% (w/v) NaCl, forming black-coloured and irregular colonies on GYM agar. Chemotaxonomic and molecular characteristics of the isolate matched those described for members of the genus Geodermatophilus. The DNA G+C content of the novel strain was 75.4 mol%. The peptidoglycan contained meso-diaminopimelic acid as a diagnostic diamino acid. The main phospholipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, a not yet structurally identified aminophospholipid and a small amount of phosphatidylglycerol; MK-9(H4) was identified as the dominant menaquinone and galactose was a diagnostic sugar. The major cellular fatty acids were branched-chain saturated acids: iso-C16:0 and iso-C15:0. The 16S rRNA gene sequence of the isolate showed 94.6-97.0% sequence similarities with those of five members of the genus: Geodermatophilus ruber DSM 45317(T) (94.6%), Geodermatophilus obscurus DSM 43160(T) (94.8%), Geodermatophilus siccatus DSM 45419(T) (96.2%), Geodermatophilus nigrescens DSM 45408(T) (96.7%) and Geodermatophilus arenarius DSM 45418(T) (97.0%). Based on the evidence from this polyphasic taxonomic study, a novel species, Geodermatophilus telluris sp. nov., is proposed; the type strain is CF9/1/1(T) (=DSM 45421(T)=CCUG 62764(T)).