The Whole Genome Sequencing And Mechanism Of Action Study Of Biocontrol Bacteria Brevibacillus Brevis X23

Tobacco is an important economic crop,China is the largest tobacco acreage and production country in the world.Tobacco black shank and bacterial wilt are the two soil-borne diseases of tobacco production,They often mixing occur in southern area of China,cause serious harm to tobacco quality and safety.The biocontrol bacteria X23isolated from the rhizosphere soil of tobacco,and then identified as Brevibacillus brevis X23by16S rDNA phylogenetic analysis. Bacteria of this genus can secrete large amounts of antibacterial substances,is considered to have the potential to develop a good biocontrol strain,therefore,they increasingly favored by plant protection science and technology workers.In this paper,firstly,conducted the test of biocontrol bacteria B.brevis X23against phytophthora parasitica var. nicotianae (breda de haan) tucker and Ralstonia soanacearum E F Smith on plate in the laboratory.Then,respectively,developed greenhouse pot experiment and field biocontrol tests,to study the biocontrol effect of B.brevis X23prevent tobacco black shank and bacterial wilt in the specific condition and natural environment,which provided a reference for biocontrol bacteria X23'promotion and application.On the basis of the above study,this paper studied the mechanism of action of B.brevis X23against phytophthora parasitica var. nicotianae (breda de haan) tucker and Ralstonia soanacearum E F Smith.The results showed that X23's secreted antimicrobial peptide could destroyed the plasma membrane of Ralstonia soanacearum E F Smith,resulted in the leakage of cell contents,and ultimately kill the R.solanacearum.Similar to the mechanism of action of it inhibited bacteria,the secreted antimicrobial peptide of X23could also cause phytophthora parasitica var. nicotianae (breda de haan)tucker'smembrane rupture,and under an optical microscope (1000times),the obvious plasmolysis could be observed.In order to clone the encoding gene of X23's secreted antimicrobial peptides,the paper also build B.brevis X23's genome fine map,bioinformatic analyzed the whole genome of X23,then diged out of the six non-ribosomal synthesis of antimicrobial peptides encoding gene cluster. These findings lay the foundation for the genetic improvement ofB.brevisX23.