Identification And Research Of A Biocontrol StrainXe01Against Tobacco Bacterial Wilt Caused By Ralstonia Solanacearum

Tobacco bacterial wilt caused by Ralstonia solanacearum,is a soil-born bacterial disease. The fifteen biological characteristics of the endophytic bacterial strains isolates from the lateral root of the different disease tobacco(K326) in experimental field.Via repeatedly confront culture test,endophytic bacteria strainXe01has the best antibacterial activity in the all.The study was to investigate the endophytic bacteria strainXe01associated with traditional fermentation starters through a traditional culture-dependent method and a molecular identification approach.The main result of this research as follows:1、Adapting the plate dilution method,2.3×104cfu/g,8.6×104cfu/g,6.5×106cfu/g and3.5×107cfu/g endophytic bacteria were isolate from the blade,cane,taproot and lateral root of the tobacco. Through the plate confrontation training Fifteen strains of endophytic bacteria on Ralstonia solanaceae antagonism.strainXe01has the strongest antibacterial activity,which diameter of inhibition zone against R.solanaceae was31.5mm,Further antimicrobial spectrum of strainXe01was tested against Magnaporthe Oryzae,Alternaria alternata Keissler,Phytophthora Capsici,Colletotrichum Capsici, Colletotrichum gloeosprioides, Phytophthora Parasitica, Cladosporium Cucumerinum.2、To study of strainXe01morphological characteristics,Biochemical and physiological characteristics of the culture characteristics,identification of16S rDNA and Biology automatic microbiology analysis system.StrainXe01was identified as Bacillus amyloliquefaciens. the accession of them in the GenBank was JX477175.3、For the high production of antimicrobial substance growth, the medium composition were optimized by single factor carbon,nitrogen,inorganic and orthogonal experiments L9(34). As a result, The optium medium were glucose8.0g, beef extract3.0g and anhydrous calcium chloride4.0g.Fermentation temperature was30℃,pH at7.0,rotate speed was170r/min and fermentation time was56h.After the optimization, antagonistic activity of the strainXe01enhanced35.87%.4、StrainXe01fermentation product stability of the results show that the strain has unstable ability to high temperature and Proteinase K, but it does not lose its antagonistic activity,There was significant drop in activity at pH3-5,under UV can not impact the antimicrobial substances. a part of antinicrobial substances was extractioned by actone and ether.