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Two dark pink pigmented bacterial strains (M3(T) and M11) were isolated from crude oil contaminated desert sand from Kuwait. Both strains were Gram-stain-negative and small-rod to oval-shaped bacteria. Strains M3(T) and M11 grew at 1342 degrees C (optimum, 30-35 degrees C) and pH 6.5-9.0 (optimum, 7.0-7.5). No additional NaCl was required for the growth of both strains. The genomic DNA G+C content of strains M3(T) and M11 were 69.5 and 69.0 mol%, respectively. Both strains were closely related and the mean DNA-DNA hybridization value was 92 +/- 1 %. 16S rRNA gene sequence comparisons of both strains indicated that they belong to the genus Roseomonas. Strains M3(T) and M11 had a sequence similarity of 97.3 and 97.4% with Roseomonas oryzae JC288(T), respectively. Both strains had <97% 16S rRNA gene sequence similarity with other members of the genus Roseomonas. Strain M3(T) showed 18 +/- 2 and 13 +/- 2% reassociation (based on DNA-DNA hybridization) with R. oryzae KCTC 42542(T) and Roseomonas cervicalis KACC 11686(T), respectively. The major cellular fatty acids (>5 %) were identified as C-18 : 1 omega 6c/C-18 : 1 omega 7c, C-16 : 1 omega 6c/C-16 : 1 omega 7c and C-16 : 0 in both strains. Both strains showed diphosphatidylglycerol, phosphatidylglycerol, phosphatidyl-ethanolamine, phosphatidylcholine and unidentified glycolipid as major polar lipids. Based on distinct phenotypic, genotypic and phylogenetic differences from the previously described taxa, we propose the classification of strains M3(T) and M11 as representative of a novel species in the genus Roseomonas, for which the name Roseomonas deserti sp. nov. is suggested. The type strain is M3(T) (= KEMB 2255-459(T)=JCM 31275(T)).