木糖醇对奶牛无乳链球菌的抑菌作用及其生物被膜干预

Investigation of xylitol on antibacterial effect of Streptococcus agalactiae from dairy cows and its biofilm intervention

通过电镜观察木糖醇对引起奶牛乳房炎的无乳链球菌生物被膜形成的影响并探索其抑菌机理。首先采用卡尔加里生物被膜发生装置与结晶紫染色法定量分析和评价无乳链球菌生物被膜形成能力,再选取生物被膜形成能力强的典型菌株,应用内置载体片法构建生物被膜,并进行扫描电镜观察;最后,分别通过透射及扫描电镜分析不同浓度的木糖醇对无乳链球菌及其生物被膜的影响。内置载体片法试验结果显示,无乳链球菌的生物被膜完全成熟需要连续培养4d,此时细菌黏附于接触表面,分泌多糖基质等并逐渐将其自身包绕其中;透射电镜观察结果显示,木糖醇可通过破坏无乳链球菌结构来抑制其生长,且随浓度增加抑菌效果亦显著增加。此外,不同质量浓度木糖醇溶液(0.05,0.15,0.30和0.50kg/L)处理的载体片上生物被膜细菌数量均有不同程度的减少,其中以0.50kg/L最为显著。结果表明,木糖醇可改变无乳链球菌超微结构,也可通过破坏其生物被膜来抑制细菌生长。

The effect of xylitol on the intervention of biofilm formation of Streptococcus agalactiae from dairy cow mastitis was observed by electron microscopy and its antibacterial mechanism was explored.Firstly,the calgary biofilm formation device and crystal violet staining method were used to quantitatively analyze and evaluate the ability of S.agalactiae biofilm formation.Then typical isolate with strong biofilm formation ability was selected to further establish the biofilm by using the built-in carrier slice method and scanning electron microscopy.Finally,the alteration of the isolated S.agalactiae and its biofilm resulted from different concentrations of xylitol was analyzed by transmission and scanning electron microscopy.The built-in carrier chip test revealed that it takes 4 successive days for the full maturity of biofilm of S.agalactiae,the matured biofilm demonstrated that the bacteria adhere to the contact surface,secrete the polysaccharide matrix,etc.and gradually wrap them around themselves.Transmission electron microscopy exhibited that xylitol could inhibit the growth of S.agalactiae,and the antibacterial effect was improved with the increase of concentration.Furthermore,the number of biofilm-coated bacteria on the carrier tablets treated with different concentrations of xylitol solution(0.05,0.15,0.30and 0.50kg/L)was reduced to different degrees,among them 0.50kg/L is the most significant.Xylitol can alter the ultrastructure of S.agalactiae and inhibit the growth of bacteria by destroying its biofilm.