Label-Free Surface-Enhanced Raman Scattering-Based Microbial Whole-Cell Biosensor for Acute Toxicity Assessment in Water

Aquatic toxicity assessment is extremely important to ensuring water safety. Typically, the evaluation was accomplished by introducing bioluminescent bacteria, where the weakened luminescence was used to calculate the acute toxicity. Herein, a new microbial whole-cell biosensor was proposed for aquatic toxicity evaluation using a label-free surface-enhanced Raman spectroscopy (SERS) technique with Escherichia coli (E. coli) as a model organism. The proposed strategy required neither special bacteria strains nor mediators. The dose-dependent SERS signal of the exposed model bacteria can be directly acquired. For the model toxic chemical Cu2+, the half-inhibitory concentration (IC50) was found to be 3.87 mg/L. The method also helps understand the mechanism of toxicity of bacterial cells after exposure to a toxic environment, providing a multiparameter view of the changes in bacterial physiological metabolism induced by toxicants.