Kinetics of Polychlorinated Biphenyl Dechlorination and Growth of Dechlorinating Microorganisms

Abstract

The present study has investigated a correlation between the kinetics of polychlorinated biphenyl (PCB) dechlorination and the growth of dechlorinating microbial populations. Microorganisms were eluted from Aroclor 1248-contaminated St. Lawrence River (NY, USA) sediments and inoculated into clean sediments spiked with Aroclor 1248 at 10 concentrations ranging from 0 to 3.12 micromol/g sediment (0-900 ppm). The time course of PCB dechlorination and population growth were concurrently determined by congener-specific analysis and the most probable number technique, respectively. The specific growth rate was a saturation function of PCB concentrations above the threshold concentration (0.14 micromol/g sediment, or 40 ppm), below which no dechlorination or growth of dechlorinations were observed. The maximum growth rate was 0.20/d with a half-saturation constant of 1.23 micromol/g sediment. The yield of dechlorinating microorganisms showed a peak at 0.70 micromol/g sediment (200 ppm), with a value of 10.3 x 10(12) cells/mol Cl removed, and decreased below and above this concentration. The dechlorination rate (micromol Cl removed/g sediment/d) was a linear function of Aroclor concentration. Both the log of this rate and the maximum level of dechlorination were significantly correlated with growth rate. The biomass-normalized dechlorination rate (micromol Cl removed/g sediment/cell/d) was first order because of the exponential manner of the population growth. The first-order rate constant was a saturation function of Aroclor concentrations, with a maximum of 0.24/d (a half-life of 2.9 d) and a half-saturation constant of 1.18 micromol/g sediment, which are similar to the constants for growth. These results indicate that the dechlorination rate is tightly linked to the population growth of dechlorinating microorganisms.

Molecular characterization of polychlorinated biphenyl-dechlorinating populations in contaminated sediments

“…Quantitative analysis of Aroclor 1248 was performed by using a gas chromatograph (Hewlett-Packard 5890II, Agilent, USA) equipped with a 63 Ni electron capture detector and a HP-5 fused silica capillary column (Agilent). The gas chromatography conditions used were described elsewhere (Rhee et al, 2001). The PCB congeners in the Aroclor 1248 extract were identified and quantitated using a calibration standard containing a 1:1:1:1 mixture of Aroclors 1016, 1221, 1254, and 1260 (0.2 ȝg/ml of each in hexane).…”

Life cycle assessment comparison of substrates for the bioremediation of pentachloroaniline under acidogenic/methanogenic conditions

“…recommended. Moreover, the reductive dechlorination rate of haloorganic compounds is generally proportional to biomass concentration (Rhee et al 2001;Pavlostathis and Prytula 2000;Tas 2006), indicating that the population size of dechlorinating microorganisms is crucial to the PCA transformation rate. In addition, Fig.…”

Evaluation of the Eological Management and Enhancement Alernative for Remediation of the K1007-P1 Pond

“…Most ofthese factors affect the composition and activities of the microbial community, and therefore, the rate and extent of decholorination (Wiegel and Wu 2000). Rates of dechlorination have been observed to be a linear function of PCB concentrations in sediment (Rhee et al 2001, Cho et al 2002, at least above the threshold concentrations described below. The presence of residual petroleum in sediments often provides a nonaqueous phase analogous to organic matter that lowers solution concentrations of PCBs and rates of dechlorination (Zwiemik et al 1999).…”

“…The presence of residual petroleum in sediments often provides a nonaqueous phase analogous to organic matter that lowers solution concentrations of PCBs and rates of dechlorination (Zwiemik et al 1999). The rate of dechlorination is closely related to the population growth of dechlorinating microorganisms (Rhee et al 2001). Although aging sometimes affects the bioavailability and transformation rates of organic compounds, the dechlorination of PCBs aged in sediments occurs at rates similar to those in freshly spiked sediments (Abramowicz et al 1993).…”

“…PCB dechlorination at Lake Hartwell, SC, apparently occurs at sediment concentrations much lower than 50 mg/kg (Magar et al 2005b). It has also been suggested that the yields of PCB-dechlorinating microorganisms are reduced at very high concentrations of PCBs (e.g., above 200 mglkg, Rhee et al 2001). …”