A novel, non-motile, coccoid, Gram-stain-positive actinobacterium, designated BMG 862T, was isolated from a marble sample collected from the Bulla Regia monument, Northern Tunisia. Its taxonomic position was determined using a polyphasic approach. Results from chemotaxonomic analyses showed MK-9(H4), MK-8(H4) and MK-9(H2) as the predominant menaquinones. The major polar lipids comprised diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, glycophosphatidylinositol, hydroxy-phosphatidylethanolamine and three unidentified phospholipids. The fatty acids consisted of significant amounts (≥10 %) of iso-C16 : 0, C17 : 1ω8c, iso-C15 : 0 and C16 : 1ω7c. Phylogenetic analysis on the basis of 16S rRNA gene sequence comparisons showed that strain BMG 862T belongs to the genus Blastococcus, being most closely related to Blastococcus saxobsidens (=DSM 44509T) (99.5 %) and Blastococcus capsensis (=DSM 46835T=CECT 8876T) (99.3 %). The genomic DNA G+C content of the organism was 74.7 mol%. Results of DNA-DNA hybridization and physiological tests allowed differentiation of strain BMG 862T from related species. The strain was also characterized by its ability to hydrolyse xanthine. On the basis of phenotypic and molecular characteristics, strain BMG 862T (=DSM 46842T=CECT 8884T) represents the type strain of a novel species of the genus Blastococcus, for which the name Blastococcus xanthinilyticus sp. nov. is proposed.
Keywords: Geodermatophilaceae; polyphasic taxonomy; xanthine hydrolase.