Microbial transformations of arsenic : potential applications in decontamination actions

Arsenic occurs in water and soil either as a consequence of human activities or from natural leaching or dissolution of arsenic-rich minerals. The toxicological effects of arsenic are related to its chemical form and oxidation state: arsenite [As(III)] is about 100-times more toxic and mobile than arsenate [As(V)]. Human exposure to arsenic typically occurs through drinking water. The World Health Organization recommends 10 \u3bcgL-1 as a maximum arsenic concentration in drinking water. Groundwater of several Italian Regions, including Lombardia, Lazio, Puglia and Sardegna, have been found to contain As concentrations higher than 10 \u3bcg L-1 (D.Lgs. 31/2001) due to the complexity of the geological history and to substratum rock types of the regions. Arsenic can be removed from contaminated waters by physico-chemical as well as biological techniques. The former, however, have some limitations, such as the use of chemicals with environmental impact, the production of large amount of sludge, the need of secondary treatment, high costs and in some cases a low efficiency. The bacterial oxidation of As(III) to As(V) is being a promising technology for effective removal of As from ground water by decreasing its bioavailability. From contaminated water it can be converted into an insoluble compound and co-precipitated with the hydro-oxides of Fe and Mn. The aim of this project is to study the indigenous microbial communities of some As-rich groundwaters from Lombardia, to investigate the relationships between microbial populations and water characteristics (e.g., chemical composition and redox status), and to utilize As-oxidising bacteria as new agents for biological decontamination of drinking water. The multidisciplinary approach adopted in the solution of the problem sees environmental chemists and microbiologists interacting with molecular biologists, with the objective to add knowledge and to complement the research on arsenic already carried out by the Environmental Microbiology Group of DiSTAM and by the Soil Chemistry group of DiProVe. Prof. Muyzer, who will coordinate the research together with Prof. Andreoni, is an internationally recognised molecular ecologist that will teach the Italian scientists to gain new laboratory skills and to deal with the management of research, from scientific data interpretation to technology transfer. The scientific collaboration with an internationally recognised researcher will enable the Italian team to create a new research network at international level, and to stimulate mobility through joint research partnerships in co-operation programmes between different organisations. The specific scientific impact of this proposal is to increase the knowledge of the quality of ground water in Lombardia with regard to the presence of As, one of the most toxic contaminant in drinking water, and to the development of an environment-harmless biological treatment. The aims of the project fit with the general objectives of Fondazione CARIPLO, which finances this exchange program within the call \u201cPromote the formation of human capital of excellence. Promoting international projects aimed at recruiting young researchers\u201d