METHODS FOR DETECTION OF ARSENIC METABOLIZING BACTERIA

Microbial activities can directly impact the mobility and toxicity of arsenic species in the environment. In order to identify dissimilatory arsenate respiring prokaryotes (DARP), we have investigated enrichment culture media formulation and developed biochemical and molecular probes. Hydrogen appeared to be the best electron donor (with acetate as the carbon source) and 5 mM sodium arsenate the most affective for both growth and orpiment production. Polyclonal antibodies raised against a conserved region of ArrA (the catalytic subunit of the respiratory arsenate reductase) were shown to cross react with several species of arsenate respiring bacteria. Western blot and genomic analysis indicate that most but not all ArrA cross-react with the antisera. Degenerate oligonucleotide primers that amplify a portion of arrA were designed for use with Denaturing Gradient Gel Electrophoresis (DGGE). Preliminary results were successful in amplifying arrA from different enrichment cultures. These tools complement a growing arsenal available for detecting DARP in situ.