香芹酚对食源粪肠球菌生物膜形成的抑制作用

Inhibition Effect of Carvacrol to Biofilm Formation of Foodborne Enterococcus faecalis

通过分析菌体泳动能力、生物膜内菌落总数和胞外多糖含量、生物膜的微观结构及相关基因表达量来研究香芹酚对粪肠球菌R612-Z1生物膜形成的影响和可能的抑制机制。研究结果表明香芹酚对该菌的最小抑菌质量浓度为512μg/mL。1/4 MIC(128μg/mL)香芹酚对生物膜膜内活菌总数没有显著影响(P>0.05),而能够显著抑制菌体的泳动能力和生物膜内胞外多糖的合成。扫描电镜和激光共聚焦显微镜观察发现香芹酚存在时生物膜结构松散、细胞之间连接不致密、膜厚度降低并有裂缝、不平整。通过荧光定量PCR发现1/4 MIC香芹酚存在时与粘附和胞外多糖合成相关的基因表达量变化明显下降。本研究结果表明1/4 MIC香芹酚对粪肠球菌R612-Z1生物膜有明显的抑制作用,其作用可能通过抑制菌体的初期粘附和胞外多糖的合成来完成。

In this paper,the effect of carvacrol to inhibit biofilm formation of E.faecalis R612-Z1 and the possible inhibition mechanisms were studied by analyzing the bacterial swimming and swarming abilities,the total bacterial counts and extracellular polysaccharides contents in biofilm,the changes of biofilm microstructure and the expression levels of related genes.The result of this study showed that the minimum inhibitory concentration of carvacrol to E.faecalis R612-Z1 was 512 μg/mL.The total bacterial counts in biofilm were not significantly changed after 1/4 MIC(128 μg/mL) carvacrol treatment,but the bacterial swimming and swarming abilities and exopolysaccharides contents in biofilm were meaningfully deceased.The biofilm structure became loose and rough,and membrane thickness was reduced after 1/4 MIC(128 μg/mL) carvacrol treatment observed by scanning electron microscopy and confocal laser scanning microscopy.Real-time PCR revealed that the expression levels of genes associated with adhesion and extracellular polysaccharide synthesis were significantly decreased after carvacrol treatment.This result indicated that carvacrol had a significant inhibitory effect on E.faecalis R612-Z1 biofilms by inhibiting initial adhesion and synthesis of extracellular polysaccharides of E.faecalis R612-Z1.