Abstract
A whole-cell biosensor developed with yeast Saccharomyces cerevisia to detect the toxicity of chlorothalonil has been developed. This biosensor relied on the inhibition effect for metabolism by toxicants to provide detection and the degree of toxicity to yeast cells. In order to further improve the toxic sensitivity of yeast cells biosensor, the effect of the action time, the initial pH value of the medium and the temperature on inhibiting cell growth were investigated. Response surface regression analysis was conducted to obtain optimal culture conditions. Th effects of treated yeast morphology, ROS, DNA, caspase 3 activity were analyzed. This optimized yeast as a biosensor was used to detect chlorothalonil and heavy metals. The results are as follows: at optimal culture conditions, EC50 values of chlorothalonil to yeast biosensor determined at incubation time 4 h increased from 0.25 µg·mL-1 in the control to 0.006 µg·mL-1, which increased by 41.67 times. Compared with the control yeast cells, the morphology of optimized yeast cells were more transparent, with significantly increased intracellular vesicle rate and cell membrane permeability, intracelluar ROS increased siginificantly, DNA bands extracted was ladder, and caspase 3 activity was stimulated. The yeast biosensor had a high sensitivity to heavy metals. After analysis, many treated cells were apoptosis which was the main reason for the increasing sensitivity to detect harmful substances. It was found that the method provides a new idea for the detection of harmful substances in the environment.
Yeast cells biosensor could be used to detect harmful substances in the environment, sunch as chlorothalonil, heavy metals. Even through chemical analysis methods, such as ICP-MS and High Performance Liquid Choromatography (HPLC), have strengths in accuracy and limit of detection, it is impossible to evaluate the cytotoxicity and the biological effect of waste water by chemical result alone, and it is also expensive, prolix and complicated. However, the yeast cell biosensor is easy to operate, is sensitive to various toxicants, comparable to the other totxicity detection methods, is cheap in cost, and has. Therefore, the method which used yeast cells as biosensor will have great potential in the detection of the cytotoxicity of waste water in the future.
