Proposal that the arsenite-oxidizing organisms, Thiomonas cuprina and "Thiomonas arsenivorans" be reclassified as strains of Thiomonas delicata
Résumé
The three As(III)-oxidizing Betaproteobacteria Thiomonas delicata, Thiomonas cuprina and "Thiomonas arsenivorans" were isolated from mining sites in geographically distinct areas, namely Japan, Germany and France, respectively. They are all able to oxidize As(III), but only "T. arsenivorans" and T. cuprina show efficient autotrophic growth with As(III) and are able to grow on single carbon compounds. Those two organisms are motile, but T. delicata is not. Only T. cuprina can grow autotrophically on chalcopyrite. The three strains share more than 99% gene sequence similarities for their 16S rRNA genes and their 16S-23S ITS regions. DNA-DNA hybridization results are above or close to the suggested threshold value of 70% for the definition of bacterial species. They show very similar fatty acids profiles with differences only in five minor ones. They possess phylogenetic and chemotaxonomic similarities supporting their reclassification as a single species. We propose to reassign "T. arsenivorans" and T. cuprina as strains of T. delicata (type strain DSM 17897T).