Gordonia metallireducens sp. nov., a tellurite- and selenite-resistant bacterium isolated from the sediment of an acid mine drainage stream

Abstract

A polyphasic taxonomic study was carried out on strain TSed Te1T, 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 Te1T revealed genetic differences at the species level, which were further substantiated by differences in several physiological characteristics. The dominant fatty acids were C16 : 0, C18 : 1, C16 : 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(H2) was the only menaquinone found. Mycolic acids of C56–C60 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 Te1T (=NRRL B-65678T=DSM 114093T).