Isolation and partial characterization of PCB and PAH-degrading bacterial consortia from contaminated sites in Stephenville and Argentia, Island of Newfoundland

Abstract

Soil and sediment samples collected from PCB contaminated sites in Stephenville (soil) and Argentia (sediment) were used to isolate several microbial consortia capable of growth on biphenyl medium. These cultures were enriched by repeated transfer on biphenyl medium, and laboratory scale experiments were carried out to determine the ability of the Argentia consortia to degrade naphthalene, phenanthrene, phloroglucinol and toluene, as well as Aroclor 1254. The Stephenville cultures were also tested for the ability to degrade Aroclor 1254, using test tube, flask experiments (both soil-free and soil slurries) and bioreactor experiments. -- Results show that all of the cultures tested grew on biphenyl medium and several of the cultures were able to also degrade PAHs and PCBs. Results of soil slurry experiments showed that the addition of enriched consortia plus biphenyl as cosubstrate stimulated biodegradation of Aroclor 1254. Growth on Aroclor 1254 was also shown in soil-free microcosms by an increase in optical density at 600 nm, as compared with controls. Dry weight of cells also increased when compared with controls. A sequential anaerobic/aerobic treatment regime was also found to be successful in degrading Aroclor 1254. -- These results show that indigenous bacteria, enriched by growth on biphenyl medium, can be useful in treatment of PCB-contaminated soils and sediments.