title: 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.
authors.affiliation: Wadsworth Center, New York State Department of Health, Albany 12201, USA. rhee@wadsworth.org
authors.forename: G Y
authors.initials: GY
authors.lastname: Rhee
authors.forename: R C
authors.initials: RC
authors.lastname: Sokol
authors.forename: C M
authors.initials: CM
authors.lastname: Bethoney
authors.forename: Y C
authors.initials: YC
authors.lastname: Cho
authors.forename: R C
authors.initials: RC
authors.lastname: Frohnhoefer
authors.forename: T
authors.initials: T
authors.lastname: Erkkila
mesh_terms: D001140:Aroclors / Q000378:metabolism*; D001673:Biodegradation, Environmental; D018533:Biomass; D002138:Calibration; D002713:Chlorine / Q000378:metabolism; D005618:Fresh Water; D019015:Geologic Sediments; D007700:Kinetics; D009518:New York; D010084:Oxidation-Reduction; D011078:Polychlorinated Biphenyls / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D001140:Aroclors; D014874:Water Pollutants, Chemical; C028617:aroclor 1248; D002713:Chlorine; D011078:Polychlorinated Biphenyls