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SALTIKOV LAB

Strains of Shewanella sp. ANA-3 that can (yellow tubes) or cannot (clear tubes) respire arsenate. The yellow mineral (orpiment) is formed by the reaction of As(III) with sulfide to yield As2S3.

Chad W. Saltikov
495 Physical Sciences Building (PSB)
Phone: (831) 459-5520

My research group studies molecular mechanisms of microbial redox transformation of toxic metals, specifically arsenic. Contamination of drinking water supplies with arsenic is a worldwide public health concern. Microbes play a key role in arsenic contamination by altering the redox state of arsenic through oxidation and reduction reactions. These redox reactions can significantly influence the fate and transport of arsenic in sediments and aquifers. The anaerobic reduction of arsenate to arsenite is known to liberate arsenic from contaminated sediments under certain environmental conditions. Populations that rely on these types of ground waters may be at risk for developing cancer associated with the consumption of arsenic contaminated water. This is the current situation in Bangladesh where nearly 60 million people rely on aquifers contaminated with arsenic well above the WHO standard of 10 µg/l.

Research in my lab focuses on the use of model organisms and genetic approaches to investigate mechanisms for arsenic biotransformations. The model organism that we have been using is the bacterium Shewanella sp. strain ANA-3. This bacterium is a facultative anaerobe and can respire arsenate, insoluble minerals such as manganese oxides and ferric (hydr)oxides, and a variety of other organic and inorganic electron acceptors. The recent completion of the genome sequence has been a valuable resource in our research and is allowing us to probe deeply into the molecular mechanisms for arsenic respiration and detoxification.

Here are some current research topics in my lab:

• Regulation of arsenate respiration (dissimilatory arseante reduction) in Shewanella sp. ANA-3.
• What are the roles of c-type cytochromes in anaerobic respiration of arsenic and iron(III) (hydr)oxides?
• Genetic and geochemical mechanisms underlying arsenic mobilization.
• Investigating the microbial ecology of arsenate respiring and arsenite oxidizing microbes.
• How does the hyperthermophilic archaeon Pyrobaculum arsenaticum respire arsenic?

List of arsenate respiring microbes
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