Chris Maltman

A polyphasic taxonomic study was carried out on strain TSed Te1 T , isolated from sediment of a stream contaminated with acid drainage from a coal mine. The bacterium forms pink-pigmented colonies and has a rod–coccus growth cycle, which also includes some coryneform arrangements. This bacterium is capable of growing in the presence of up to 750 μg ml −1 tellurite and 5000 μg ml −1 selenite, reducing each to elemental form. Nearly complete 16S rRNA gene sequence analysis associated the strain with Gordonia , with 99.5 and 99.3 % similarity to Gordonia namibiensis and Gordonia rubripertincta , respectively. Computation of the average nucleotide identity and digital DNA–DNA hybridization comparisons with the closest phylogenetic neighbour of TSed Te1 T revealed genetic differences at the species level, which were further substantiated by differences in several physiological characteristics. The dominant fatty acids were C 16 : 0 , C 18 : 1 , C 16 : 1 and tuberculostearic acid. The DNA G+C content was 67.6 mol%. Major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside, while MK-9(H 2 ) was the only menaquinone found. Mycolic acids of C 56 –C 60 were present. Whole-cell hydrolysates contained meso -diaminopimelic acid along with arabinose and galactose as the major cell-wall sugars. On the basis of the results obtained in this study, the bacterium was assigned to the genus Gordonia and represents a new species with the name Gordonia metallireducens sp. nov. The type strain is TSed Te1 T (=NRRL B-65678 T =DSM 114093 T ).