Bio-adsorption and Bio-transformation of Arsenic by Acidithiobacillus ferrooxidans BY3

Arsenic, a toxic element in the environment, has seriously threatened the health of hundreds of millions of people in the world. Meanwhile, microorganisms play an important role in the adsorption and bio-transformation of arsenic. Here, we compared the biological characteristics of Acidithiobacillus ferrooxidans BY3 in different media systems, such as arsenic bio-adsorption and bio-transformation capacities. We show that arsenic stress significantly affected the pH and Eh of the culture systems, as well as the oxidation rates of Fe2+ and bacteria numbers. Furthermore, arsenic influenced bacterial structure and composition of the cell membrane, caused volume decreased and changed the vibration conditions of characteristic peaks of surface groups (-CH2, -NH, and -OH) on cell membranes. In addition, At. f-BY3 shows high bio-adsorption abilities and certain bio-transformation abilities for iAs(III). Bio-adsorption and conversion efficiency was also shown to be significantly affected by Fe2+ concentrations in the reaction systems. Statistic analysis revealed 10.07-fold increase of the transformation ability of iAsIII into iAs(V) in the 9 K growth media containing 1600 mg/L NaAsO2 compared with that in the 1 K growth media. Our findings contribute to understand the applications and microbiological mechanisms of Acidithiobacillus ferrooxidans in arsenic pollution.