Purification Of The Active Substance Of Rice Blast Fungus Strain NK413 And Its Mechanism

NK413, a strain of Streptomyces albulus, the metabolite of which has abroad antagonistic spectrum to plant pathogenic fungi, and had potential biocontrol ability. So the antifungal substance produced by Streptomyces NK413 was separated and purified, the preliminarily mechanism of control on Magnaporthe grisea was studied in this reasch.The purification results of fermentation liquid of NK413 showed that: because of the thermal stability of antimicrobial substance, heating and high pressure leaching methods were used to get the pretreatment of fermentation broth. The pretreatment of fermentation broth was enriched through ethanol precipitation, and then the sediment dissolves in water and was seprated by active carbon. the active principle was separated and analyzed by X-5 macroporous resin column chromatography. There were four chromatographic peaks, peak 1 had the the strongest antibacterial activity, so the active principle was furtherly analyzed by silica gel column chromatography. five chromatographic peaks were shown , the antibacterial activity of peak 2 was the strongest. The purity examination of its components by HPLC indicated that the retention time of the main component was 13.024 min which occupied 84.12% of the total sample peak area. Then purified furtherly by HPLC, the components whose retention time was 13.024 min was collected and concentrated by the method of nitrogen-blowing. 0.23g dry powder was gotten and examed by HPLC, the purity was 98.7%. the UPLC results showed two peaks, the retention time was 2.92min and 4.08min respectively, 73.04% and 15.63% of total peak area. The Waters Quattro Premier XE analysis of the two components indicated that the molecular weight was 314 and 477.Studies on mechanisms of antibiotic NK413 action showed that growth of hyphae was inhibited at low concentration of antibiotic, and could be totally inhibited at high concentration. After treated with abtibiotic NK413, the characteristic of Pyricularia grisea hyphae changed significantly, hyphae puffed up and became short, the cell wall was getting unintegral, with nearly disappeared cell chorion inside which only a little remainder and lipid stockpile particle .