Assessment of the Microscreen Phage-Induction Assay for Screening Hazardous Wastes

Abstract

The Microscreen phage-induction assay, which quantitatively measures the induction of prophage λ in Escherichia coli WP2s(λ), was used to test 14 crude (unfractionated) hazardous industrial waste samples for genotoxic activity in the presence and absence of metabolic activation. Eleven of the 14 wastes induced prophage, and induction was observed at concentrations as low as 0.4 picograms per ml. Comparisons of the mutagenic activity of these waste samples in Salmonella and their ability to induce prophage λ indicate that the phage-induction assay was a more sensitive indicator of genetic damage for this group of wastes. All but one of the wastes that were mutagenic to Salmonella were detected by the phage-induction assay, and 5 wastes not mutagenic to Salmonella were genetically active in the phage assay. The enhanced ability of the phage-induction assay to detect genotoxic activity may be related to the constituents comprising these waste samples. Partial chemical characterizations of the wastes showed high concentrations of carcinogenic metals, solvents, and chlorinated compounds, most of which are detected poorly by the Salmonella assay. However, recent studies of the induction of prophage by these chemical classes have suggested that phage induction may be a sensitive endpoint for these groups of chemicals.