Selection Of Serratia Marcescens Degradation-Related Genes And Its Cloning Transformation

Imazethapyr is one of the important pesticides for weed control in China.It is a typical herbicide with long residual time,it usually remains in the soil about 33-37 months or even longer.Regardless of the use of imazethapyr in crop rotation or continuous croppingit is very easy to cause phytotoxicity to the crops,reduce the amount or even lose it.Serratia marcescens has been intensively studied in the fields of biomedicine,biological control and environmental restoration.Serratia marcescens exists widely in various natural environments for a long time and is affected by various environmental factors.Some strains have the ability to repair the environment and can degrade certain harmful substances or adsorb heavy metals.Therefore,screening of Serratia marcescens capable of degrading imazethapyr and studying its key genes for degrading imazethapyr is very important to alleviate the environmental pollution caused by imazethapyr residues.In this paper,a strain of Serratia marcescens that has been efficiently degraded by imazethapyr in a soybean field environment that has been screened in the laboratory is used to analyze the degradation of imazethapyr by Serratia marcescens by ultra performance liquid chromatography tandem mass spectrometry(UPLC-MS).Intermediate products were preliminary analyzed,and the key genes of Serratia marcescens degradation of imazethapyr were screened with transcriptome sequencing data.Two key genes of Serratia marcescens degradation of imazethapyr were screened out and cloned successfully.These two genes,of which SerhcaC gene encodes 105 amino acids,are hydrophilic proteins.The amino acid sequences encoded by the SerhcaC gene were compared by BlastP and found to be a 3-phenylacetate oxygenase subunit;the SerhutU gene encodes 575 amino acids and is a hydrophilic protein.The amino acid sequences encoded by the SerhutU gene are compared by BlastP.It was found to be urocanate hydratase.And the SerhcaC-pGEX and SerhutU-pGEX prokaryotic recombinant expression vectors were successfully constructed and transformed into E.coli DE3 competent cells to obtain E.coli recombinant strains SerhcaC-DE3 and SerhutU-DE3.Through the cloning and bioinformatics analysis of SerhcaC and SerhutU genes,the construction of their prokaryotic expression vectors,and the transformation of their prokaryotic expression,they have laid the foundation for subsequent research on the ability of SerhcaC and SerhutU genes to degrade imazethapyr.Promoting the key issue of pesticide residues on the later crops is very important for maintaining ecological balance,improving the economic value of soybean fields and protecting forests around soybean fields.