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

饮用水砷污染是一个全球性问题，对受影响人群造成慢性健康问题。症状包括皮肤变色、恶心、腹泻、血管问题和癌症。在孟加拉国等国家，估计有超过3000万人暴露在高水平的砷中，加拿大、美国和世界各地都发现了高砷含量的局部地区。已经开发出从饮用水中去除含砷化合物的方法，但这些方法受到成本的限制，特别是在发展中国家。细菌已被确认使用含砷化合物作为能量来源。已知这些砷降解细菌在环境中的砷的动员中起作用。在将含砷化合物转化为较难溶形式的策略中，也对细菌进行了测试，以促进它们从饮用水供应中去除。然而，所涉及的基因和途径还没有得到很好的理解——一些与含砷化合物氧化或还原有关的基因已经被确定，但仍有许多工作要做。最近，已经确定了其中几种细菌的DNA序列。从这些基因组中获得的信息可以用来鉴定与砷代谢有关的新基因。本研究将利用基因组序列信息作为开发新策略的起点，以识别参与环境中砷循环的细菌。我们将寻找可以作为砷污染标记的基因和微生物。所采用的方法将涉及直接从已知砷含量高的环境中分离出的DNA测序，例如受污染的井或采矿作业下游地区。这些信息将用于开发高通量诊断工具，用于研究受砷污染的地区。通过这一举措开发的工具和方法有可能应用于分析其他环境污染物。

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.