Transfer of Thiosphaera pantotropha to Paracoccus denitrificans

Comparative sequence analysis of in vitro-amplified 16S rRNA genes of Thiosphaera pantotropha GB17T (T = type strain) and Paracoccus denitrificans LMG 4218T revealed identical 16S rRNA primary structures for the two organisms. The level of overall DNA similarity of Thiosphaera pantotropha GB17T and P. denitrificans DSM 65T is 85%, as determined by quantitative DNA-DNA hybridization. Therefore, we propose the transfer of Thiosphaera pantotropha to P. denitrificans. The closest relative of Thiosphaera pantotropha and P. denitrificans is Thiobacillus versutus, as revealed by comparative 16S rRNA sequence analysis. These organisms are members of the alpha subclass of the Proteobacteria. Within this subclass, Thiosphaera pantotropha, P. denitrificans, and Thiobacillus versutus form a phylogenetic group with Rhodobacter sphaeroides, Rhodobacter capsulatus, and "Erythrobacter longus."