In order to control potato early blight by microorganisms, plate confrontation tests were used to screen antago﹣nistic strains, then the antimicrobial activity were detected in the current work. Among the 44 strains of endophytic fungi and bacteria, seven bacterial strains gave a significantly inhibitory effect against pathogen, off which strains H3 demon﹣strated the highest antagonistic ability, whose antibacterial circle diameter was 5.50mm. Antimicrobial activity of strain H3 broth in LB was the highest, and strain H3 broth with 16.7% concentration gave 71.17% inhibition rate. Strain H3 broth cause the abnormality of pathogenmycelium, i.e. the apical expansion to vacuole-like sphere, the thicker and shortersec﹣tion between hyphaeseptum, as well as the shrinked protoplast. Therefore, strain H3 could better control potato early blight.%为更加有效地利用微生物资源控制马铃薯早疫病，采用平板对峙法，筛选马铃薯早疫病病原菌的拮抗菌株，通过含毒介质法探究拮抗菌株的抗菌活性。结果表明：44个供试内生真菌和细菌的菌株中，7株细菌对马铃薯早疫病病原菌有显著的抑菌作用，其中菌株H3的拮抗能力最强，采用平板对峙法显示，菌株H3对马铃薯早疫病病原菌抑菌宽度为5.50 mm；对H3培养基类型进行筛选，含毒介质法显示LB发酵液的抑菌活性最高，16.7％的H3发酵液的抑制率为71.17％；菌株H3发酵液能导致马铃薯早疫病病原菌菌丝形态变化：菌丝顶端出现空泡状的膨大，菌丝隔间细胞变粗变短，原生质收缩。结果说明H3可以拮抗马铃薯早疫病病原菌。
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