BACTERIAL BIOSENSORS FOR THE TOXICITY ASSESSMENT OF SOLID-WASTE

Two metal-lux fusions were constructed in Alcaligenes eutrophus by tra nsposon Tn4431 mutagenesis. The resulting strains, named AE1239 (pMOL9 0::Tn4431) and AE1433 (pMOL30::Tn4431, pMOL28), were respectively emit ting light in the presence of copper ions and in the presence of zinc, cadmium, cobalt, and lead ions. Both strains were freeze dried and us ed as microbial bioluminescent sensors for the evaluation of incinerat or fly-ashes (IFA) and soils contaminated by heavy metals. Two detecti on protocols (with or without direct contact between the bacterial sen sors and the IFA) were used to test different batches of IFA that were either not treated or treated in order to be used as recycled materia l. The bacterial light production measured with a luminometer in the p resence of increasing concentrations of IFA was compared with the IFA metal concentration measured by inductively coupled plasma emission sp ectrometer. The same methodology was used to compare different soils s amples from a sandy soil area severely contaminated by heavy metals. B oth biosensors could successfully assess the bioavailability of heavy metals. This bioassay appeared to be very simple and rapid since no pr etreatment of the samples was required. Those biosensors can either be used to predict the potential risk of the use of heavy metal-recycled materials in the environment or serve as a rapid screening tool for t he efficacy of remediation practices used on contaminated soil. (C) 19 96 by John Wiley & Sons, Inc.