【摘要】 生物被膜广泛存在于自然环境中，作为细菌重要的抗应激机制之一，具有较强的耐药性、致病性及免疫逃逸的功能。为建立牦牛(Bos grunniens)致病性大肠杆菌(Yak pathogenic Escherichia coli, YPEC)生物被膜形成模式菌株，探讨各种外界因子对YPEC生物被膜形成的影响，本研究以YPEC天祝-1、天祝-2、天祝-3、青海-2、青海-3和青海-4分离株为研究对象，通过微孔板定量法鉴定YPEC生物被膜的形成能力，以筛选出生物被膜强菌株作为优势菌株，进而分析生物被膜形成的影响因素。结果表明，YPEC不同分离株形成生物被膜的能力不同，天祝-1株、天祝-2株和天祝-3株均为强生物被膜形成者，青海-3株和青海-4株均为中等生物被膜形成者，青海-2株为弱生物被膜形成者，其中天祝-3株形成生物被膜的能力最强(P<0.05)。当培养时间24 h、温度37℃、pH 7.5、起始菌液浓度1.3×10~9 CFU/mL、10%菌液比例条件下天祝-3株生物被膜形成量最佳；LB培养基中添加20μg/mL DNA和2%蔗糖均有助于促进生物被膜的形成，而添加不同浓度的NaCl、葡萄糖和乳糖均对生物被膜的形成有抑制作用。本研究为从生物被膜角度开展YPEC防控提供数据支撑和理论依据。更多还原

【Abstract】 Biofilms exist widely in the natural environment. As one of the important anti-stress mechanisms of bacteria, they have strong resistance, pathogenicity and immune escape functions. The aim of this study was to establish a biofilm-forming model strain of yak(Bos grunniens) pathogenic Escherichia coli(YPEC), and to explore the effects of various boundary factors on the biofilm formation of YPEC. In this study, the isolates strains of YPEC Tianzhu-1, Tianzhu-2, Tianzhu-3, Qinghai-2, Qinghai-3 and Qinghai-4 were selected as the research object. Microplate quantative method was used to identify the biofilm formation ability of YPEC, and strains with strong biofilm formation were selected as the dominant strains, and then the influencing factors of biofilm formation amount were analyzed. The results showed that different isolates of YPEC had different biofilm forming abilities. Tianzhu-1, Tianzhu-2, and Tianzhu-3 strains were all strong biofilm formers, while Qinghai-3 and Qinghai-4 strains were medium biofilm formers, and Qinghai-2 strain were weak biofilm formers. Among them, Tianzhu-3 strain had the strongest ability to form biofilms(P<0.05). The optimal amount of biofilm formation of Tianzhu-3 strains was achieved when culture time was 24 h, temperature was37 ℃, pH 7.5, initial bacterial solution concentration was 1.3×10~9 CFU/mL and 10% bacterial liquid ratio. The addition of 20 μg/mL DNA and 2% sucrose in LB medium could promote the formation of biofilm, while the addition of different concentrations of NaCl, glucose, and lactose all had inhibitory effects on the formation of biofilms. The above results provide data support and theoretical basis for YPEC prevention and control from the perspective of biofilm.更多还原