Screening Of Biocontrol Agent Against To Potato Black Scurf And Its Antibacterial Mechanism

Potato black scurf which is caused by Rhizoctonia solani Kuhn is a soil-borne disease, and it is also one of the main disease of potato production. With the expansion of the potato planting area, it was more serious year by year, it has seriously affacted on the yield and quality of the potato and blocked the rapidly development of the potato industry, This study was isolated bio-control microorganisms from potato tuber’rhizosphere soil sample from Inner Mongolia, liaoning, hebei, shanxi. It was designed for providing the basic and biological basis for biological control of potato black scurf. It was solved the environmental pollution problem which was caused by the traditional chemical prevention and opened up new ideas for the prevention and control of potato black scurf. The main research results are as follows:, It were separated and screened156strains which had the antagonist effect from91rhizosphere soil sample which were from different regions of the potato. There were112strains which belonged to bacterium,41strains which belonged to actinomyces,3trains which belonged to fungi. There was4.5%stains which have the antagonist effect. XC5and XA3strains have the most stable antagonist effect, inhibition zone of5.1mm and6.5mm.Through the outdoor potted control effect to the determination, The XC5strain’s control efficicency reached66.1%against to potato black scurf, XA3strain reached57.4%.XC5strain was identified as Bacillus subtilis (Bacillus subtilis) through the traditional bacteria morphological characteristics, physiological and biochemical test, and combined with16S rDNA sequence analysis, strains of XA3was identified as Paenibacillus polymyxa (Paenibacillus polymyxa).It was found that XC5was colonized well in potatoes of the rhizosphere, roots, stems whatever in soil sterilization or natural soil through colonization ability test, after the filling root treatment30days, the processing natural soil can it still detected the bacteria colonization of the rhizosphere soil was9×105cfu/g, the root and stem’s bacteria colonization was respectively for2×103cfu/g and5×102cfu/g.It found that XC5strain’s antimicrobial active substances had volatility through strain of XC5antifungal active material preliminary study, it had strong inhibition effect against to Rhizoctonia solani, inhibition rate reached93.58%, explaining the XC5 . strain’s existence of main antagonist active substances likely was a volatile substance.XC5strain’s best initial inoculation quantity was6%, loadd liquid was25mL/250mL, pH8.0,30℃, it produced maximal bacterium quantity using maltose and NH4NO3after cultivating56h in optimizing cultivated temperature, pH, time, nitrogen source, carbon source through improving SDAY medium.