Whole Genome Analysis Of Two Rhizosphere Bacteria With Bio-control Function And Joint Application

To control the plant diseases using biological method,promote plant growth,our laboratory isolated two strains which with broad-spectrum antibacterial activity from a lot of soil microorganisms,they were Pseudomonas aurantiaca JD37 and Bacillus velezensis S3-1 respectively.The two strains of bacteria has been applied in the experiments and the effect of promoting is obvious.In this experiment,we want to find more genetic characteristics about these two bacteria by using the bioinformatics methods,analyze its antibacterial metabolic mechanism,at the last combine the two strains and apply to soil repair experiments which was infected by pathogenic fungus,lay the foundation of the final composite improver development.Using bioinformatics tools to dig into the whole genome sequence of JD37 found that there were osmotic regulation genes and eight kinds of antibiotic resistance genes associated with environmental adaptability.Then,based on the secondary metabolites predicted results of the whole genome known the gene clusters associated with the synthesis of phenazine-1-carboxylic acid(PCA)and nitrate pyrrole cephalosporins(Prn).In this process,compare the gene clusters of secondary metabolites among the pseudomonas strains found the resorcinol synthesis gene cluster in JD37,which provides clues for investigating the relationship with others.In addition,we found JD37 has one incomplete prophage and three complete in its whole genome.JD37's analysis results shows that it's suitable for the next experiments related to disease suppression.After 16 S rDNA identification found that S3-1 and Bacillus amyloliquefaciens FZB42 had the highest homology,then we extracted the total DNA of S3-1 and sequenced.We submitted the complete sequence to NCBI database after correction and joint,and the registration number is CP016371.On the basis of whole genome characteristic,we named S3-1with Bacillus velezensis S3-1.Combined with sequenc-ing information and NCBI database annotation results that S3-1 whole genome sizeof 3929772 bp,GC content is 46.50%,excluding plasmid and CRISPs(clusters of regular interspaced short palindromic repeats sequence).S3-1 contains 86 tRNA,27 rRNA,22 genes island,57 antibiotic resistance genes and 19 secondary metabolism gene clusters,including surfactin biosynthetic gene cluster,fengycin biosynthetic gene cluste,bacilysin biosynthetic gene cluster,ect.Because of the genome analysis results about JD37 and S3-1 shown both strains have a good base for biological control,therefore,we joint JD37 and S3-1 to explore the bacteriostatic effect.At first,we respectively measured the antibacterial efficiency of tomato grey mould of bacteria was 65.74% and 59.20%,and they weren't antagonistic between them.Then,through experiments found that using YPG medium cultivated 36 h,the bacteria attain to the maximum number in the medium.Finally,using the index number of Botrytis cinerea fungus hypha in soil judged the effect,we found JD37 and S3-1 at the volume ratio 1:1 had a goog effect of controlling soil-borne disease.Although the effect of controling diease in soil is relatively good,in such aspects as fermentation optimization,the field experiment results still needs further study.