本文研究了百里香酚在亚抑菌浓度条件下对阴沟肠杆菌(Enterobacter cloacae) C4生物膜形成的抑制作用。首先确定百里香酚对E.cloacae C4的最小抑菌浓度,然后测定亚抑菌浓度的百里香酚对生物膜内菌落总数、菌体泳动能力和胞外多糖含量的影响,观察生物膜内的细菌形态以及三维结构的变化,并进一步测定与生物膜形成相关基因的相对表达量。结果表明:百里香酚对该菌的最小抑菌浓度(MIC)为256 μg/mL。1/4 MIC百里香酚在不影响浮游细菌生长和生物膜内活菌总数的情况下,显著(P<0.05)抑制菌体的泳动能力和生物膜内胞外多糖的合成,与生物膜形成相关(细胞粘附和胞外多糖合成)基因相对表达量显著下调。百里香酚处理后生物膜内细菌菌体变长、生物膜厚度降低,膜结构松散。因此百里香酚在亚抑菌浓度下对阴沟肠杆菌C4生物膜形成有抑制作用。
In this study,the inhibitory effect of thymol on E.cloacae C4 biofilm formation at sub-inhibitory concentration was studied. Firstly the minimal inhibitory concentration(MIC)of thymol on E.cloacae C4 was determined. Then the effect of sub-inhibitory concentration of thymol on the bacterial counts in the biofilm and themobile ability of the cells and the content of exopolysaccharides were determined. Changes in bacteria morphology and three-dimensional structure of biofilm were observed. The relative expression of genes associated with biofilm formation were determined. The results indicated that the MIC of thymol was 256 μg/mL. 1/4MIC of thymol was not affect the growth of planktonic bacteria and the bacterial counts in biofilm but significantly(P<0.05)inhibited the mobile ability of bacteria and the content of exopolysaccharides.The expression of genes related to biofilm formation(cell adhesion and the synthesis of exepolysaccharides)was down-regulated. The biofilm bacteria morphology grew longer,the biofilm thickness decreased and the membrane structure was damaged after thymol treatment. Therefore,thymol has an inhibitory effect on the biofilm formation of E.cloacae C4 under the sub-inhibitory concentration.