Characterization of arsenic-resistant bacteria isolated from water wells in Tucumán, Argentina

Abstract

The growth of eighteen bacterial strains, previously isolated from arsenic contaminated water wells at "Los Pereyra", Tucumán was tested in the presence of different concentrations of arsenite and arsenate. An arsenic-tolerance assay in Petri-dishes with LB agar medium at 25% of concentration (LB25) was performed to determine the resistance of the isolates to As(III) and As(V). The concentrations tested went from 5 to 20 mM for As(III) and 50 to 200 mM for As(V). All the isolates showed to be resistant to all the concentrations tested for As(V), but only seven isolates were able to grow at the maximum concentration of 20 mM for As(III). Growth curves in LB25 broth, LB25+As(III) 5 mM and LB25+As(III) 10 mM were conducted for the seven high-resistant isolates. PCR 16S amplifications were performed on total DNA from each isolate and were sequenced. The resulting sequences showed α-, β-, γ- Proteobacteria and Actinobacteria as the main members of the bacterial communities.