Blastococcus colisei sp. nov, isolated from an archaeological amphitheatre.

The taxonomic position of an actinobacterial isolate, designated strain BMG 822, isolated from limestone from the Amphitheater of El Jem (Coliseum Thysdrus), Tunisia, was established using a polyphasic approach. Strain BMG 822 was found to grow well at 30 °C and pH 6.5-8.0, and to be coral-coloured, Gram-positive, catalase and oxidase negative. Whole cell hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid, glucose, galactose and ribose. The phospholipids detected were diphosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine, hydroxy-phosphatidylethanolamine, an unidentified glycophospholipid and six unidentified phospholipids. MK-9(H) was found to be the predominant menaquinone, followed by MK-9(H) and MK-9. The major cellular fatty acids were identified as iso-C, C ω9c, C ω8c and iso-H-C. The G+C content of the DNA (73.2%) is typical of the genus. High degrees of 16S rRNA gene sequence similarity were found with the type strains of the genus Blastococcus (97.1-98.3%) followed by the type strains of Modestobacter (96.8-97.8%). Based on the above data and the phenotypic differences from the type strains of Blastococcus species, it is proposed that the isolate BMG 822 (=DSM 46837=CECT 8823) should be classified as the type strain of a novel species, Blastococcus colisei sp. nov.