Use of lux bacterial biosensors to assess bioremediation potential and constraints at a BTEX contaminated site
The response of the lux-biosensors to a range of environmental pollutants was determined, as well as the stability of the biosensors to a range of environmental parameters. The biosensors were found sensitive to a range of pollutants at environmentally relevant concentrations. These included the pollutants prevailing at the contaminated site (BTEX and major co-contaminants). Analysing the bioluminescence dose-response curves to different pollutants, it was observed that the shape of the response appeared to be indicative of the nature of the contaminant present. The application of the lux-biosensors in the screening of groundwater and sediment samples from the contaminated site, showed different levels of toxicity which correlated well with chemical analysis. The sample screening produced a toxicity map of the site, facilitating the identification of hot-spot areas that could be further investigated. Samples with high levels of toxicity were serial diluted and dose-response curves determined to increasing concentrations of the toxic sample, in site uncontaminated groundwater. The shape of the dose-response curve was indicative of the nature of the main pollutant present. The toxic effect of a pollutant detected by the biosensors in spiked environmental samples (groundwater from the study site) correlated with the effect of the same pollutant on mineralisation. This allowed subsequent use of biosensor toxicity for predictive assessment of degradation potential in the presence of the pollutant tested, validating the use of the lux bioassay as a management tool for bioremediation. The bioremediation of the major contaminants (BTEX) on site can be constrained by the presence of co-contaminants or adverse environmental conditions that inhibit microbial activity. The determination of these constraints is crucial for the success of the bioremediation technologies. Using biosensor response linked to sample manipulations, it was possible to determine the contribution of broad classes of pollutants to the total toxicity of the samples.