Geodermatophilus arenarius sp nov., a xerophilic actinomycete isolated from Saharan desert sand in Chad

A novel Gram-positive, aerobic, actinobacterial strain, CF5/4(T), was isolated in 2007 during an environmental screening of arid desert soil in Our, Cassoni, Chad. The isolate grew best in a temperature range of 28-40 degrees C and at pH 6.0-8.5, with 0-1 % (w/v) NaCl, forming brown-coloured and nearly circular 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 75.9 mol %. The peptidoglycan contained meso-diaminopimelic acid as diagnostic diaminoacid. The main phospholipids were phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, diphosphatidylglycerol and a small amount of phosphatidylglycerol; MK-9(H-4) was identified as the dominant menaquinone and galactose as diagnostic sugar. The major cellular fatty acids were branched-chain saturated acids: iso-C-15:0 and iso-C-16:0. The 16S rRNA gene showed 96.2-98.3 % sequence identity with the three members of the genus Geodermatophilus: G. obscurus (96.2 %), G. ruber (96.5 %), and G. nigrescens (98.3 %). Based on the chemotaxonomic results, 16S rRNA gene sequence analysis and DNA-DNA hybridization with the type strain of G. nigrescens, the isolate is proposed to represent a novel species, Geodermatophilus arenarius (type strain CF5/4(T) = DSM 45418(T) = MTCC 11413(T) = CCUG 62763(T)).