Toxicity Screening of Environ- Mental Samples Utilizing a Bacterial Bioassay

Preliminary studies have shown that the bioassay based on inhibition of alpha-glucosidase biosynthesis (AGB) in Bacillus licheniformis is useful in the acute toxicity screening of environmental samples. Alpha-glucosidase is an extracellular enzyme induced by the presence of maltose in the environment of the cell. The enzyme degrades maltose into glucose residues acting at the 1, 4-alpha-glycoside linkages. Colorimetric measurement of enzyme production is used to determine toxic effects. Earlier studies have shown that the bioassay is comparable with the Microtox assay and appears to be sensitive to the presence of metals in aqueous samples. Bioassays can be valuable tools in identifying environmental samples that may contain high levels of toxicants such as metals. Using bioassays in preliminary assessments of samples can be a cost-savings step and can help direct future analysis that may involve more expensive chemical tests. We are currently using the Bacillus licheniformis AGB bioassay in conjunction with chemical analysis to screen drinking water and aqueous extracts of soil samples collected from three communities in southeast Missouri. Data collected indicated a correlation between elevated metal concentration in the samples and decreased enzyme production in the bioassay.