两种培养基对铜绿假单胞菌和大肠埃希菌生物被膜厚度的影响

目的探讨营养成分不同的两种培养基对临床分离的铜绿假单胞菌和大肠埃希菌形成生物被膜形态的影响。方法使用电击转化将pSMC21转入临床分离的3株铜绿假单胞菌和3株大肠埃希菌体内，构建表达绿色荧光蛋白的菌株。在Luria-Bertani（LB）和M9葡萄糖基础培养基中以盖玻片为支持表面，进行细菌生物被膜的连续培养。经过12天的培养周期，使用共聚焦激光扫描显微镜检测盖玻片上生物被膜的厚度。使用方差分析检验每个样本5个测量值的重复性，并用配对T检验来分析同一株细菌在两种培养基中生物被膜的厚度变化。结果pSMC21可以在6株临床分离株中稳定表达绿色荧光蛋白；每个样本5个测量值重复性好，其差异无统计学意义（P=0．46）；大肠埃希菌在LB和M9培养基中形成生物被膜平均厚度的差异无统计学意义（t=-0．42，P〉0.7），而铜绿假单胞菌在LB培养基中形成的生物被膜更厚，其差异有统计学意义（t=3．46，P〈0．02）。结论铜绿假单胞菌所形成生物被膜的平均厚度因培养基成分的不同而有显著差异，而大肠埃希菌所形成生物被膜的平均厚度则不受培养基成分不同的影响。

Effects of two culture media on the thickness of biofilms formed by Pseudomonas aeruginosa and Escherichia coli

Objective To study the effects of different levels of nutrient abundance on the thickness of biofilms formed by bacteria.Methods Three GFP-tagged clinical strains of P.aeruginosa and 3 GFP-tagged clinical strains of E.coli were constructed with the plasmid pSMC21,and bacterial biofilm culture was carried out for 12 days.Thicknesses of biofilms in 144 samples were measured with confocal laser scanning microscopy(CLSM) and analyzed by variance and pair T test.Results pSMC21 expressed green fluorescent protein in all 6 bacterial strains.In the cultures,P.aeruginosa formed thicker biofilms with LuriaBertani(LB) than with M9(t=3.46,P<0.02),but no statistically significant differences were observed in the thickness of biofilms formed by E.coli in the two culture media(t=-0.42,P>0.7).Conclusion Thickness of biofilms was affected by the kinds of culture media for P.aeruginosa but not for E.coli.