药用牡丹拮抗内生细菌的筛选鉴定及优化培养

Screening,Identification and Optimization of Antagonistic Endophytic Bacteria from Root of Medicinal Paeonia suffruticosa

目的:研究具有拮抗金黄色葡萄球菌的药用牡丹内生细菌,并通过优化目的菌株培养条件提高其抑菌活性。方法:采用滤纸片法和抑菌圈法,对分离于亳州、洛阳和菏泽的牡丹内生细菌进行筛选,获得最优拮抗菌株,根据常规分类学结合16S rDNA进行鉴定,并通过单因素试验、正交设计试验对其优化培养。结果:菌株X21的抑菌圈直径为17.3 mm,对病原菌有较好的抑制作用,鉴定为短小芽孢杆菌Bacillus pumilus,优化培养后X21对病原菌的抑菌性增强;培养基的最佳碳源为可溶性淀粉、氮源为牛肉膏,优化发酵条件组合为:5%接种量、20%装液量和180 r/min的转速。结论:药用牡丹根内细菌具有拮抗性,且优化培养后内生细菌抑菌活性增强。

Objective:To study the endophytic bacteria against Staphylococcus aureus from the roots of medicinal Paeonia suffruticosa,and to improve the antibacterial activity of the target strain with the optimization of fermentation conditions.Methods:The filter paper method and the inhibition zone method were used in isolating the endophytic bacteria from the roots of medicinal Peaonia suffruticosa in Bozhou,Luoyang and Heze.The conventional taxonomy combined with phylogenetic analysis of 16 S rDNA gene sequences were engaged in the molecular identification of the optimal antagonistic strain,and the fermentation condition was optimized by single factor and orthogonal experiment.Results:Strain X21 had a good inhibitory effect on pathogens with the maximal antibacterial diameter of 17.3 mm,and was identified as Bacillus pumilus.The strain X21 enhanced bacteriostasis of pathogenic bacteria under optimized culture conditions,the soluble starch,beef extract constituted the optimum medium source of carbon and nitrogen,and the optimum fermentation conditions for X21 were inoculum volume 5%,liquid volume 20%,and rotation speed 180 r/min.Conclusion:The endophytic bacteria from the roots of medicinal Paeonia suffruticosa has antagonism and the bacterial antibacterial activity is enhanced after optimized culture.