Identification Of DMS Chemotactic Receptors In The Marine Alcaligenes Faecalis J481

β-Dimethylmercaptopropionic acid(DMSP)is an important sulfur-containing organic compound in the marine environment,which is degraded by microorganisms or algal plants in the ocean and releases the volatile gases dimethyl sulfide(DMS),acrylic acid,and a proton.DMS and its sulfur compounds influence global climate change,not only driving the global sulfur cycle but also being a major cause of acid rain formation.In recent years,the reaction of DMSP cleavage by DMSP lyase has received much attention from scientists.The mechanism of this process,especially the chemotactic receptors involved in this process,has not yet been discovered internationally and needs to be studied in depth.Therefore,in this study,we used Alcaligenes faecalis J481 to firstly determine whether the deletion mutant of its DMSP lyase gene lost its chemotactic response.Second,to determine the important regulatory role of the che Y gene in the chemotaxis response pathway.Third,to identify the signaling molecules of its entire signaling pathway.Fourth,to screen and clarify the genes encoding chemotactic receptor proteins in Alcaligenes faecalis J481.The main results are as follows:1.By verifying the chemotactic phenotype of DMSP lyase gene mutant(Δddd Y mut)on DMSP,acrylic acid,and aspartic acid on soft agar chemotaxis plates,we found that A.faecalis J481 with deletion of the ddd Y gene loses its chemotactic response function.It was thus concluded that the chemotaxis of A.faecalis J481 is dependent on the expression of ddd Y gene(dependent on DMSP lyase).2.By constructing a deletion mutant che Y,an important gene in the chemotactic signaling pathway,we demonstrated its crucial role in the chemotactic response and provided a basis and control for subsequent phenotypic validation.3.To clarify the chemotactic signaling molecule as DMS from different chemotactic DMSP,DMS,and acrylic acid after quantitative analysis by chemotactic phenotypes and capillaries.4.By whole-genome sequencing,bioinformatics analysis and prediction of the structural characteristics and functions of chemokine receptor proteins,a total of eight potential genes encoding chemokine receptors were detected from the genome of A.faecalis J481: D6I95＿01015,D6I95＿05705,D6I95＿12910,D6I95＿17300,D6I95＿17410、D6I95＿17420、D6I95＿17565 and D6I95＿17570.The deletion mutant strains of these eight genes were constructed,and the D6I95＿17420 gene was screened as the gene encoding the chemotactic receptor protein of DMS,and the back-complemented and overexpressed strains were constructed by back-expansion technique to verify the chemotactic phenotype and further identify the chemotactic receptor gene of DMS.Comprehensive experiments showed that this paper verified the dependence on the expression of ddd Y gene(DMSP lyase gene)in the chemotactic response of alkaliproducing A.faecalis J481,the response signal molecule was DMS,and the gene encoding the chemotactic receptor protein was D6I95＿17420.In addition,the important role of che Y gene in bacterial chemotaxis was verified.