A biosensor based toolkit for investigating microbial remediation on a BTEX contaminated site
In this project, a tool-kit based upon the use of genetically modified luminescent bacterial biosensors was applied to support the remediation of a site with a history of BTEX contamination. The luminescence response from the biosensors indicated that there were high levels of toxicity on one area of the site, which may have resulted in a constraint to microbial activity. Treatment of samples by air sparging and activated charcoal resulted in a reduction in sample toxicity and BTEX availability. These data were used to assist the planning of site remediation strategies. The biosensor suite was then used to predict the potential constraint to BTEX bioremediation of co-contamination with heavy metals. Soils of varying pH were contaminated with zinc and copper to represent a model system. Biosensor analysis indicated that increased metal bioavailability in soils of low pH may affect the ability of a microbial community to degrade toluene. The BTEX degradation capacities of in situ microbial communities on the study site were investigated using biofilm culture units. Results of this work indicated that a different community was isolated from each groundwater well. The largest active biofilms and greatest degradation capacities were found in samples taken from groundwater wells with the highest BTEX concentrations. Biofilm samples were also subjected to molecular analysis, with amplification of 16S sequences achieved in all samples. Degradative genes, tod and bed, were only successfully amplified from samples taken from groundwater wells with the highest BTEX concentrations.