The Study On Screening Antagonistic Strain For Wheat Take-all Disease And Its Antifungal Substance

In order to get biocontrol resource to prevent Wheat take-all disease, weused Gaeumannomyces graminis var. tritici(Ggt)GYY4-4as target, after antagonistictesting on the plate, we selected four strains had strong antimicrobial impact on Ggt.their antagonistic efficiency were:59%,53.8%,51.3%,60.9%, Selected LDJ11strainas the starting strain, and LDJ11was identified as Bacillus vallismortis, When measured itsantimicrobial spectrum, it showed obviously antagonistic activity on Valsaceratersperma, Fusarium monihforme, Fusarium oxysporum, Colletotrichumgloeosporioides Penz, Diplocarpon mali Harada et Sawamura, G.graminis Var.tritici,Rhizoctorua solani and Fusarium graminearum. especially on Ggt and chestnutanthracnose, its antagonistic effect is particularly significant, which could reach60.9%and59.7%. the result of pots testing had illustrated that its control efficiency topathogenic fungi GYY4-4was65.67%. The mycelia treated with strainLDJ11wasdeformity, swollen at the top and protoplasm exuded when observed by microscope.The culture medium and condition of LDJ11, such as Carbon and nitrogen sources,original pH value, culture temperature, rotation speed, inoculation conditions andcullure time were studied. Aceording to the studying results, the best culturalconditions were carbon and nitrogen sources were glucose and peptone, The bestfilling amount150mL~175mL for a300ml triangle bottle, original pH7.0, amountof inoeulation2%, culture temPerature37℃, rotation speed200r/min cultured48hours.Using aammonium sulafte at50%sautration combined with methanol extractionto extract the active substances in the fermented liquid, and the properties of activesubstance were insensitivity to UV, temperature, protease, and pH, The crude extractcarried out anion exchange chromatography and reversed phase chromatography byHitrap Q HP column and C18, and The active components were detected by HLP-MS,at last we identifyed that the main components with antibacterial activity werelipopeptide iturins, plipstatin and surfactin.