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目的:研究一种天然来源抑菌剂对常见致病性细菌(金黄色葡萄球菌,蜡状芽孢杆菌,铜绿假单胞菌,大肠杆菌)以及石斛病原真菌(烟草疫霉菌)的抑制作用。方法:从东海沙滩泥土中分离纯化菌株,通过牛津杯法及对峙法筛选对四株致病性细菌和一株石斛病原真菌具有抑制作用的活性菌株;通过观察菌体形态,16S rRNA测序、Gen Bank比对,对最优活性菌株进行鉴定;通过优化菌株培养条件,获得活性物质产生最佳发酵条件。结果:从样品中共分离52株菌,6株菌发酵液提取物对病原细菌具有抑制作用,2株对烟草疫霉菌具有拮抗活性。选取活性最佳的菌株,通过鉴定,确定为枯草芽孢杆菌(Bacillus subtilis);其发酵液乙酸乙酯提取物对所述5株指示菌具有生长抑制活性;通过优化,确定该菌最佳培养条件为37℃,ISP2培养基,发酵培养96 h。结论:从东海中所分离获得的枯草芽孢杆菌对常见致病细菌具有较强的抑制作用,且对烟草疫霉菌具有抑制作用,可用于筛选石斛病原菌天然抑制剂的研究。
Objective: To study the inhibitory effect of a natural source bacteriostat on common pathogenic bacteria (Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Escherichia coli) and Dendrobium candidum. Methods: Strains were isolated and purified from the soil of the beach in the East China Sea. The strains that inhibited the four pathogenic bacteria and one of the pathogenic fungi of Dendrobium were screened by the Oxford cup method and the confrontation method. By observing the cell morphology, 16S rRNA sequencing, Gen Bank comparison, the best active strains were identified; by optimizing the strain culture conditions, to obtain the best fermentation conditions active substances. Results: A total of 52 strains of bacteria were isolated from the samples. The 6 strains of fermentation broth extracts had inhibitory effects on pathogenic bacteria and 2 strains had antagonistic activity against Phytophthora nicotianae. The strain with the best activity was selected and identified as Bacillus subtilis. The ethyl acetate extract of the fermentation broth had growth inhibitory activity on the five indicator bacteria. By optimizing, the optimum culture conditions of the bacteria were determined 37 ℃, ISP2 medium, fermentation 96 h. CONCLUSION: Bacillus subtilis isolated from the East China Sea has a strong inhibitory effect on common pathogenic bacteria and has an inhibitory effect on Phytophthora nicotianae. It can be used to screen natural inhibitor of Dendrobium candidum.