Abstract:

Objective　To explore the impact and molecular mechanism of resveratrol at subinhibitory concentrations on the formation of biofilms in Staphylococcus aureus. Methods　This study was from January to April 2023. We determined the minimum inhibitory concentration (MIC) of resveratrol against the SYN strain using the broth microdilution method. The formation ability of biofilms was assessed using the crystal violet method. The impact of sub-inhibitory concentrations of resveratrol on biofilm exopolysaccharide production was detected by the phenol-concentrated sulfuric acid method. The impact on the release of extracellular DNA (eDNA) in response to sub-inhibitory concentrations of resveratrol was detected through phenol-chloroform extraction. The regulatory mechanism of resveratrol on biofilm formation in the SYN strain was investigated using real-time fluorescent quantitative polymerase chain reaction (PCR). The experimental results were analyzed using the GraphPad Prism 8.0 software and presented statistically. Results　The SYN strain demonstrated a minimum inhibitory concentration (MIC) of 1 024 mg/L for resveratrol. The crystal violet staining showed that resveratrol significantly influenced the formation of Staphylococcus aureus biofilms, and the influence increased with its concentration. The subinhibitory concentrations promoted the release of Staphylococcus aureus extracellular DNA (eDNA), and enhanced the biofilm formation. The results of real-time fluorescent quantitative PCR indicated that resveratrol exhibited down-regulatory effects on the expressions of genes saeR, saeS, lrgA, and nuc, which are associated with eDNA release in Staphylococcus aureus. Conclusion　By inhibiting the SaeRS binary regulatory system of Staphylococcus aureus, the subinhibitory concentrations of resveratrol effectively decrease the expression of cardiac enzymes and the level of LrgA, leading to the release of eDNA and robustly enhancing the production of Staphylococcus aureus biofilms.

Key words:

Staphylococcus aureus, Biofilms, Resveratrol

摘要：

目的　研究亚抑菌浓度白藜芦醇对金黄色葡萄球菌生物被膜形成的影响及分子机制。方法　研究时间为2023年1月至4月。通过微量肉汤稀释法测定白藜芦醇对SYN菌株的最小抑菌浓度（MIC）。结晶紫法检测生物被膜的形成能力。苯酚浓硫酸法检测亚抑菌浓度白藜芦醇对生物被膜胞外多糖产生的影响。苯酚氯仿抽提法检测亚抑菌浓度白藜芦醇对细胞外DNA（eDNA）释放的影响。利用实时荧光定量聚合酶链式反应（PCR）检测白藜芦醇对SYN菌株生物被膜形成的调控机制。实验结果采用GraphPad Prism 8.0软件作图及进行统计分析。结果　白藜芦醇对SYN菌株的MIC为1 024 mg/L。结晶紫染色显示，白藜芦醇可显著增强金黄色葡萄球菌生物被膜的形成，并随药物浓度的升高而增强。亚抑菌浓度白藜芦醇促进金黄色葡萄球菌eDNA的释放，增强生物被膜的形成。实时荧光定量PCR结果显示，白藜芦醇可以下调金黄色葡萄球菌eDNA释放相关基因saeR、saeS、lrgA、nuc的表达。结论　亚抑菌浓度白藜芦醇可通过抑制二元调控系统SaeRS降低耐热核酸酶的表达以及降低LrgA的水平，从而增加eDNA的释放，强烈促进金黄色葡萄球菌生物被膜的产生。

关键词:

金黄色葡萄球菌, 生物被膜, 白藜芦醇