| Abstract: | A simple and rapid test, based on growth rate inhibition (GRI) of Pseudomonas fluorescens, is described for toxicity screening and assessment. The test involves challenging standardized suspensions [0.2 optical density (OD) at 600 nm] of exponentially growing cells with various concentrations of a toxicant at 33°C and monitoring changes in the growth rate by OD measurements after 0.5, 1.0, 1.5, and 2.0 h. The toxicity end point is measured as the effective concentration of a test sample that causes 50% inhibition of growth rate (EC50) during each designated time period. Several metal salt solutions, organic compounds, and complex effluents were screened using this test and data compared with those obtained using the Microtox® assay. Results indicated that the P. fluorescens GRI test could be used as a valuable part of a battery of short-term bioassays for toxicity screening and assessment. |
