Kinetics of a Perchlorate-Reducing Bacterium that Accumulates High Levels of Chlorate

Perchlorate (ClO4-) is found in potable water sources across the United States. Dissimilatory reduction to chloride by perchlorate-reducing bacteria (PCRB) is an effective treatment strategy, but little is known about the kinetics of PCRB. Two novel PCRB isolates accumulate high levels of chlorate during batch perchlorate reduction. Dechloromonas sp. HCAP-C and Dechloromonas sp. HCAP-1 accumulate chlorate at around 20 % and 13 % of the initial perchlorate concentration, respectively; conventional PCRB accumulate less than 3% chlorate. The kinetic parameters for HCAP-C were determined and found to be distinct from conventional PCRB. HCAP-C had low qmax values (qmax for perchlorate = 4.6 mgVSS/mgVSS-day; qmax for chlorate = 6.5 mgVSS/mgVSS-day) and high K values (K for perchlorate = 40 mg/L; K for chlorate = 20 mg/L). Perchlorate reduction rates appear to increase and chlorate accumulation appears to decrease with co-cultures of HCAP-C with conventional PCRB and chlorate-reducing bacteria.