Degradation and total mineralization of monohalogenated biphenyls in natural sediment and mixed bacterial culture

Abstract

Mixed bacterial cultures obtained from polychlorinated biphenyl-contaminated river sediments are capable of degrading monohalogenated biphenyls under simulated natural conditions. Culture conditions include river water as supportive medium and mixed bacterial cultures obtained from river sediments. Degradation occurs when the substrates are supplied as the sole carbon source or when added together with glucose. The degradation rates of 2-, 3-, and 4-chlorobiphenyl, at 30 jig ml-', were 1.1, 1.6, and 2.0 ,ug ml-' day-', respectively. Monobrominated biphenyls, including 2-, 3-, and 4-bromobiphenyl, were degraded at rates of 2.3, 4.2, and 1.4 ,ug ml-' day-', respectively. Metabolites, including halogenated benzoates, were detected by high-performance liquid chromatography and mass spectrometry. By using chlorophenyl ring-labeled monochlorobiphenyls as substrates, total mineralization (defined as CO2 production from the chlorophenyl ring) was observed for 4-chlorobiphenyl but not for 2-chlorobiphenyl. Rates of total mineralization of 4-chlorobiphenyl (at 39 to 385 ,ug ml-' levels) were dependent on substrate concentration, whereas variation of cell number in the range of 105 to 107 cells ml-1 had no significant effects. Simulated sunlight enhanced the rate of mineralization by ca. 400%. Polychlorinated biphenyls (PCBs) are ubiquitous anthropogenic pollutants (10, 13). Polybrominated biphenyls, although not as widespread

Plasmid-mediated mineralization of 4-chlorobiphenyl

“…Quantification of 4CB mineralization. Liberation of 14CO2 from the U-14C-chlorophenyl ring-labeled 4CB was used to measure total mineralization as described previously (18). Bacterial growth conditions, assay methods, and collection of 14CO2 were as described previously (18) with the following exceptions.…”

“…Because of their unreactive chemical structure and low water solubility, they generally are considered to be nondegradable (16). Despite this, there have been several reports of PCB degradation in mixed (4,11,13,18,24) and pure (1,14,20,23,26) bacterial cultures.…”

“…This certainly seems to be the case in PCB biodegradation since there are no known sources of PCB before their commercial synthesis in 1929 (13). Recently, we have reported the total mineralization of 4CB by a river sediment microbial population (18). From this population, several Acinetobacter and Alcaligenes isolates competent for the complete mineralization of 4CB were obtained.…”

The Bioremediation of Polychlorinated Biphenyls (PCBs): Problems and Perspectives

“…Chlorinated benzoic acids have a role in regulating bacterial PCB degradation; hence for significant degradation of PCBs to occur in the environment there is the requirement for the presence of organisms possessing genes encoding both the upper pathway (PCB degradation) and the lower pathway (chlorobenzoate degradation). In an attempted simulation of a natural river environment, Kong and Sayler (1983) showed that all .nonochlorinated and monobrominated biphenyls were degraded at low concentrations. Degradation occurred through the corresponding halogenated benzoates.…”

Ecological fate, effects and prospects for the elimination of environmental polychlorinated biphenyls (PCBs)

“…Although several mixed-culture populations have been shown to be capable of the mineralization of 4-chlorobiphenyl to carbon dioxide and water ([79,84] for only the unchlorinated ring; [112] first report of mineralization of chlorinated ring), no single species had been shown to be capable of 4-chlorobiphenyl complete mineralization until the work of Sayler et al [113]. Pure cultures were isolated from the mixed community described by Kong and Sayler [112]. These communities were capable of the complete degradation of monochlorinated and monobrominated biphenyls to C 0 2 and water.…”