Establishment And Application Of A Screening Method For Genotoxic Substances

In the modernized industrialization and agrochemical level,chemical pollutants such as industrial waste water and pesticide residues inevitably enter our life.These chemicals may endanger human health and induce DNA damage.Therefore,there is an urgent need to develop a screening method that can quickly and effectively assess the genotoxicity of chemical substances.Mass spectrometry,chromatography and other methods can effectively analyze chemical substances,but the cost is high,the operation is complicated,and the measurement time is long.Bacterial detection systems are more promising and attractive in this regard.The rapid screening test system for a wide range of genotoxic substances is mainly SOS/umu color development technology,that is,an expression vector for transferring the ?-galactosidase gene lacZ into Salmonella typhimurium,when exposed to carcinogens,the expression of lacZ can be induced,and the carcinogen in the environment can be screened by measuring the activity of lacZ.This study constructed a new rapid detection system for genotoxic substances.The expression of the phage cleavage gene SRRz was controlled by the SOS-responsive promoter umuDC,and the expression vector was introduced into Escherichia coli.The recombinant strain was incubated with the test substance,and the cels were lysed by the SOS response.After 0.5 h incubation,the naked eye was observed by naked eyes.The turbidity of the bacterial solution changes to determine whether the test substance is genotoxic.Therefore,the system has the characteristics of short detection time,simple operation,low cost,and is easy to achieve highthroughput screening.The sensitivity of the system was further tested using a variety of known toxic compounds and combinations thereof.The results showed that the system responded to these toxic compounds,and Azinphos-methyl,MMS,mitomycin C(MMC),Dichlofluanid and Dithianone's detection limits are 32 ?M,6 ?M,3.3 ?M,410 ?M and 0.04 ?M,respectively,which is more sensitive than the traditional SOS/umu method.At the same time,this paper uses the different concentrations of hexavalent chromium ions as the standard,and fits the doseeffect curve equation.According to the cracking efficiency of the test system,the equivalent chromium ion concentration can be calculated to facilitate the different substances.A comparison of the toxicity and a semi-quantitative determination of the total genotoxicity of the test substance.Using this equation to compare the toxicity of the above five toxic compounds,the results show that MMS and Dichlofluanid have the highest and lowest toxicity,respectively,consistent with the literature reports.Finally,the detection system was used to test the genotoxicity of environmental water samples.As the concentration of water samples increased,the lysis efficiency of recombinant bacteria also increased significantly,indicating that genotoxic substances were present in the water samples,equivalent to 0.08 ?M the toxicity of valence chromium ions.The above results show that the detection system developed in this paper is not only simple in operation,low in cost,but also has good sensitivity and wide detection range.It can also realize semi-quantitative determination of toxic substances by equivalent chromium ion concentration conversion.On-site real-time monitoring of genotoxic substances in the environment and high-throughput screening.