USE OF A LUX-MODIFIED BACTERIAL, BIOSENSOR TO IDENTIFY CONSTRAINTS TOBIOREMEDIATION OF BTEX-CONTAMINATED SITES

Sediment and groundwater samples obtained from a benzene, toluene, eth ylbenzene, and xylene (BTEX)-contaminated site were screened, using a bioluminescence-based (lux gene-marked) bacterial biosensor, to identi fy constraints to site remediation. Through a series of sample manipul ations and linked biosensor responses, constraints to BTEX remediation such as adverse pH, presence of nonvolatile organic contaminants, and the presence of heavy metals were investigated. Conventional chemical analysis (gas chromatography, inductively coupled plasma mass spectro scopy) was used to confirm the reliable performance of the biosensor a nd to identify its potential contribution to site management to ensure effective: remediation. The toxicity results of the biosensor were ex pressed in % maximum bioluminescence calculated against a blank of dou ble deionized water with pH adjusted to 5.5. Untreated samples caused reductions in percentage bioluminescence from 10 to 95%. Water sample W1, containing a total BTEX concentration of 30,595 mu g/L caused the highest decrease in bioluminescence (5.78%). This toxicity was signifi cantly reduced after elimination of volatile organic compounds (VOCs) (42.01%) and bioluminescence was further increased to 87.80% after rem oval of total organic matter. This suggested that VOCs were not the on ly toxic organopollutants present. Water samples giving high values of bioluminescence contained BTEX concentrations of 17 to 31 mu g/L.