ABSTRACT
Five environmental sites in Bulgaria were sampled for bacterial isolates that could transform different arsenic forms. In total, 108 bacterial strains that could grow in the presence of high concentrations of arsenic species were isolated. Only 27 from all strains show the transforming abilities. These isolates were enriched from the sediment samples, the performed classical taxonomy and analysis of the 16S rDNA gene sequence revealed them to belong to β- and γ-Proteobacteria and in particular in genera Pseudomonas, Azoarcus and Alcaligenes.