Oxidation of arsenite by Thiomonas strains and characterization of Thiomonas arsenivorans sp. nov.

Abstract

A novel bacterium, strain b6(T) (T=type strain), was isolated from a disused mine site by growth using arsenite [As(III)] as energy source in a simple mineral medium. Cells of strain b6(T) were rod-shaped, Gram-negative, non-sporulating and motile. Optimum growth occurred at temperatures between 20 and 30 degrees C, and at pH between 4.0 and 7.5. Strain b6(T) grew chemoautotrophically on As(III), sulphur and thiosulphate, and also heterotrophically on yeast extract and a variety of defined organic compounds. Several other Thiomonas strains, including the type species Thiomonas (Tm.) intermedia, were able to oxidize As(III), though only strain b6(T) and strain NO115 could grow using As(III) as sole energy source in the absence of any organic compound. The G+C content of the DNA of strain b6(T) was 65.1 mol %. Comparative small subunit (SSU) ribosomal RNA (rRNA) analysis indicated that strain b6(T) belongs to the genus Thiomonas in the beta-subdivision of the Proteobacteria. It was closely related to an unnamed Thiomonas strain (NO115) isolated from a Norwegian mining site, though sequence identities between strain b6(T) and characterized Thiomonas species were less than 95%. DNA-DNA hybridization between strain b6(T) and the type species of the genus Tm. intermedia showed less than 50% homology. On the basis of phylogenetic and phenotypic characteristics, strain b6(T) (DSM 16361(T), LMG 22795(T)) is proposed as the type strain of the new species Thiomonas arsenivorans, sp. nov.

Population Structure and Abundance of Arsenite-Oxidizing Bacteria along an Arsenic Pollution Gradient in Waters of the Upper Isle River Basin, France

“…The highest divergence (only 7% similarity) occurred between the surface waters and the groundwater PZR10, which showed the highest As concentration (1,846 g ⅐ liter Ϫ1 ). This level of As may not be the only explanation for the divergent structure, since all the As(III) oxidizers isolated up to now are capable of oxidizing the highest As concentrations (3,5,8,25,38). The low dissolved oxygen concentration (1.2 mg ⅐ liter Ϫ1 ) and a negative E h (Ϫ131 mV) measured in the PZR10 groundwater could impact the structure of this aerobic aoxB-carrying bacterial group.…”

“…Many As(III) oxidizers have been isolated from various environments, especially mesophilic ecosystems (3,5,8,16,25,27,32,38). They belong to more than 25 genera, mainly of the Proteobacteria phylum (3,32,38), and are related to organisms unable to oxidize As(III) based on 16S rRNA phylogeny.…”

“…Many As(III) oxidizers have been isolated from various environments, especially mesophilic ecosystems (3,5,8,16,25,27,32,38). They belong to more than 25 genera, mainly of the Proteobacteria phylum (3,32,38), and are related to organisms unable to oxidize As(III) based on 16S rRNA phylogeny. Diverse primer sets have been successfully developed to specifically target the functional aoxB gene (9,14,17,25,26), encoding the large molybdenum-bearing catalytic subunit of As(III)-oxidase (EC 1.20.98.1), an enzyme of the dimethyl sulfoxide (DMSO) reductase family.…”

Reassessment of the phylogenetic relationships of Thiomonas cuprina

“…Six species of Thiomonas have been described Battaglia-Brunet et al, 2006;Katayama et al, 2006): some comparative properties are summarized in Table 1. Thiomonas intermedia (the type species of the genus) and Thiomonas perometabolis share 99.7 % 16S rRNA gene sequence identity (1376/1380 aligned nucleotides) and 100 % identity (116/116 nucleotides) of their 5S rRNA gene sequences, but are recognized as distinct species, both physiologically and by DNA hybridization (KatayamaFujimura et al, 1983).…”

Confirmation of Thiomonas delicata (formerly Thiobacillus delicatus) as a distinct species of the genus Thiomonas Moreira and Amils 1997 with comments on some species currently assigned to the genus

“…However, proposed that Thiobacillus delicatus should also be transferred to the genus Thiomonas as Thiomonas delicata, on the basis of its physiological and biochemical properties (Table 1), subject to its phylogenetic relationship being confirmed by 16S rRNA gene sequencing . This has now been done and we report that Thiobacillus delicatus should henceforth be known as Thiomonas delicata sequences for other Thiomonas species using the BLAST algorithm (http://www.ncbi.nlm.nih.gov/blast/; Altschul et al, 1997) showed 99?9 % similarity of the Thiomonas delicata sequence with that of 'Thiomonas arsenivorans' (Battaglia-Brunet et al, 2006) and with those of Thiomonas sp. strain RCASK1 (AJ879998), Thiomonas sp.…”