The Te-Assay: a black and white method for environmental sample pre-screening exploiting tellurite reduction

Area of Science:

• Environmental Science
• Microbiology
• Toxicology

Background:

• Assessing bacterial cell viability and toxicity is crucial for environmental monitoring.
• Existing methods for toxicity testing can be time-consuming or require specialized reagents.
• There is a need for rapid, visual, and accessible bioassays for environmental samples.

Purpose of the Study:

• To introduce and validate the tellurite bioassay (Te-Assay) as an alternative method for quantifying bacterial cell viability.
• To establish the Te-Assay as a tool for pre-screening environmental samples for bacterial toxicants.
• To enable rapid visual assessment of relative sample toxicity.

Main Methods:

• The Te-Assay utilizes the metabolic reduction of tellurite (TeO(3)(2-)) to elemental tellurium by metabolically active bacteria as a marker.
• A black phenotype indicates tellurite reduction and normal metabolic function, while a white phenotype signifies toxicity.
• Toxicity is quantified by determining the analyte concentration causing a 50% reduction in the black phenotype (IC(50)).

Main Results:

• The Te-Assay provides a rapid visual assessment of bacterial cell viability and toxicity.
• The assay successfully identifies and quantifies the relative toxicity of environmental samples.
• Both characterized strains and environmental isolates performed well, and no proprietary reagents are required.

Conclusions:

• The tellurite bioassay (Te-Assay) is a valuable, accessible tool for assessing bacterial viability and environmental toxicity.
• The assay's visual readout and independence from proprietary strains/reagents make it suitable for broad application.
• Te-Assay facilitates efficient pre-screening of environmental samples for potential bacterial toxicants.