Genomic and metagenomic analysis of microbes and microbial communities involved in biogeochemical cycling of arsemic

Arsenic contamination of drinking water is a global problem causing chronic health problems in affected populations. Symptoms range from skin discolouration, nausea, diarrhoea and vascular problems to cancer. In countries such as Bangladesh it is estimated that over 30 million people are exposed to high levels of arsenic, and localised areas with high arsenic levels have been found in Canada, the USA and throughout the world. Methods have been developed to remove arsenic-containing compounds from drinking water supplies, but these are limited by cost especially in developing countries. Bacteria have been identified which use arsenic-containing compounds as an energy source. These arsenic degrading bacteria are known to play a role in the mobilisation of arsenic in the environment. Bacteria have also been tested in strategies to convert arsenic containing compounds into less soluble forms, facilitating their removal from drinking water supplies. However, the genes and pathways involved are not well understood - some of the genes involved in oxidation or reduction of arsenic containing compounds have been identified, but much work remains to be done. Recently, the DNA sequence for several of these bacteria has been determined. The information from these genomes could allow the identification of new genes involved in arsenic metabolism. This study will use the genomic sequence information as a starting point for developing new strategies to identify bacteria involved in arsenic cycling within the environment. We will look for genes and microbes that can act as markers for arsenic-contamination. The methods employed will involve sequencing DNA isolated directly from environments known to have high levels of arsenic, such as contaminated wells, or areas downstream from mining operations. This information will be used to develop high-throughput diagnostic tools for use in the study of regions contaminated with arsenic. Tools and methods developed through this initiative could potentially be applied in the analysis of other environmental contaminants.