Development of a Facile and High-Throughput Bioluminescence Assay Using Vibrio fischeri to Determine the Chronic Toxicity of Contaminated Samples

Pitfalls in measuring solution toxicity using the level of bioluminescence inhibition in Aliivibrio fischeri

Toxic emission from industrial activity is a serious problem, particularly with regard to the quality of water. Thus, the ISO 11348-3 standard for assessing water quality has been established. This method is used to determine solution toxicity from the bioluminescence inhibition of Aliivibrio fischeri. However, the accuracy of measurements is influenced by the selection of individual reaction time points. This study explores the utility of the area under the curve (AUC) method in water quality detection and evaluates how A. fischeri responds to three toxicants, namely ethanol, acetone, and zinc sulfate, over time. The half-maximal effective concentrations of these three substances were found to be 10.13 %, 5.02 %, and 19.49 mg/L, respectively. Compared with the results from individual reaction time point assessments, the results of AUC comprehensively captured the effects of the toxicants, including time-dependent effects and hormetic effects, by capturing dynamic changes under different toxicant concentrations and reaction times. Therefore, AUC analysis mitigates the pitfalls associated with individual reaction times and provides a more accurate and reliable assessment method for water quality detection, contributing to a better understanding of the impact of toxic substances on aquatic environments.

Investigation of Acute and Chronic Toxicity Trends of Pesticides Using High-Throughput Bioluminescence Assay Based on the Test Organism Vibrio fischeri

High-throughput acute and chronic toxicity tests using Vibrio fischeri were used to assess the toxicity of a variety of fungicides, herbicides, and neonicotinoids. The use of time points beyond the traditional 30 min of an acute test highlighted the sensitivity and applicability of the chronic toxicity test and indicated that for some compounds toxicity is underestimated using only the acute test. The comparison of EC₅₀ values obtained from acute and chronic tests provided insight regarding the toxicity mode of action, either being direct or indirect. Using a structure-activity relationship approach similar to the one used in hazard assessments, the relationship between toxicity and key physicochemical properties of pesticides was investigated and trends were identified. This study not only provides new information regarding acute toxicity of some pesticides but also is one of the first studies to investigate the chronic toxicity of pesticides using the test organism V. fischeri. The findings demonstrated that the initial bioluminescence has a large effect on the calculated effective concentrations for target compounds in both acute and chronic tests, providing a way to improve and standardize the test protocol. In addition, the findings emphasize the need for additional investigation regarding the relationship between a toxicant's physicochemical properties and mode of action in nontarget organisms.