AbstractThe study of bacteria has been an ongoing process for hundreds of years. While the field itself covers broad areas, one of the cornerstones is accurate and definitive classification of individual isolates. Through a polyphasic approach, including classical physiology and biochemical testing along with 16S rRNA gene analysis and genome sequencing, a vast number of bacteria have been officially identified, however, in spite of our best efforts, less than 1% of all bacteria have actually been properly taxonomically classified. Over the past several decades, the field of microbiology has made significant advances in the area of molecular analysis which have resulted in much more accurate classification methods. A polyphasic taxonomic study was carried out on strain TSed Te1T, isolated from sediment of a stream contaminated with acid mine drainage. Nearly complete 16S rRNA gene sequence homology related the strain to Gordonia, with 99.52 % and 99.36 % similarity to G. namibiensis and G. rubripertincta, respectively. Computation of average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) with the closest phylogenetic neighbor of TSed Te1T revealed genetic differences at the species level, further substantiated by differences in several physiological characteristics. The dominant fatty acids were C16:0, C18:1 w9c,, and 10 methyl C18:0, very characteristics of the genus Gordonia, as was the DNA G + C content of 67.6 mol %. This isolate was also resistant to very high levels of tellurite, selenite, and vanadate, a unique ability possessed by limited bacterial species. On the basis of results obtained, this bacterium was assigned to the genus Gordonia as a new species with the name Gordonia metalliredigo.
