为探讨单宁酸对金黄色葡萄球菌的抑菌机制，本试验首先采用肉汤微量稀释法检测单宁酸对耐甲氧西林金黄色葡萄球菌（MRSA）USA300菌株的最低抑菌浓度（MIC）及最小杀菌浓度（MBC）；随后采用液相色谱-质谱联用技术（LC-MS）分析1/2 MIC浓度单宁酸对MRSA USA300代谢物的影响；最后对筛选得到的代谢物进行京都基因与基因组百科全书（KEGG）分析，进一步探讨单宁酸对MRSA的抗菌机制。结果显示，单宁酸对MRSA USA300的MIC为0.625 mg/mL,MBC为1.250 mg/mL;1/2 MIC(0.312 5 mg/mL)的单宁酸作用下筛选出7种差异表达代谢物（P<0.05,FC≥1.2或≤1/1.2）。其中，磷脂酰甘油（35:3）和2,6-二叔丁基-4-硝基苯酚表达水平显著上调（P<0.05），而（Z）-13-二十二烯酰胺、1-硬脂酰基-2-亚油酰基-sn-甘油-3-磷酸胆碱、2-羟基-2′-脱氧腺苷-5′-单磷酸、D-3-磷酸甘油酸和磷脂酰甘油（23:0）表达水平则显著下调（P<0.05）。通过KEGG通路富集分析发现，这些差异代谢物富集于甘油磷脂代谢、糖酵解/糖异生、甘氨酸、丝氨酸和苏氨酸代谢等通路；进一步根据差异代谢物的KEGG信息，绘制代谢物与通路间的调控关系网络图，发现D-3-磷酸甘油酸处于核心位置，可能是单宁酸抑制MRSA的关键代谢物。本试验结果表明，单宁酸对MRSA具有抑菌作用，其机制可能与影响甘油磷脂代谢、糖酵解/糖异生、戊糖磷酸途径、甘氨酸、丝氨酸和苏氨酸代谢、半胱氨酸和蛋氨酸代谢通路有关，D-3-磷酸甘油酸可能是单宁酸抑制MRSA的关键代谢物。本研究可为进一步阐述单宁酸抑菌机制提供思路。

To investigate the antibacterial mechanism of tannic acid against Staphylococcus aureus, the Minimum Inhibitory Concentration(MIC) and Minimum Bactericidal Concentration(MBC) of tannic acid against methicillinresistant Staphylococcus aureus(MRSA) USA300 were determined using the broth microdilution method. Subsequently,liquid chromatography-mass spectrometry(LC-MS) was employed to analyze the effects of tannic acid at 1/2 MIC on the metabolites of MRSA USA300. Finally, the screened metabolites were subjected to Kyoto Encyclopedia of Genes and Genomes(KEGG) analysis to further explore the antibacterial mechanism of tannic acid against MRSA. The results showed that the MIC of tannic acid against MRSA USA300 was 0.625 mg/mL, and the MBC was 1.250 mg/mL. Under the action of tannic acid at 1/2 MIC(0.312 5 mg/mL), 7 differentially expressed metabolites were identified(P<0.05,FC≥1.2 or≤1/1.2). Among them, the expression of PG(35: 3) and 2, 6-Di-tert-butyl-4-nitrophenol were significantly upregulated(P<0.05), while the expression of 13-docosenamide(Z), PC(18:0/18:2), 2-hydroxy-d AMP, D-3-phosphoglyceric acid, and PG(23:0) were significantly downregulated(P<0.05). KEGG pathway enrichment analysis revealed that these differential metabolites were enriched in glycerophospholipid metabolism pathway, glycolysis/gluconeogenesis, glycine,serine and threonine metabolism, and other pathways. Furthermore, based on the KEGG information of differential metabolites, a regulatory relationship network diagram between metabolites and pathways was constructed, which showed that D-3-phosphoglyceric acid occupied a central position and might be the key metabolite for tannic acid to inhibit MRSA. The results of this experiment indicated that tannic acid exhibited in vitro antibacterial activity against MRSA, and its mechanism might be related to affecting glycerophospholipid metabolism, glycolysis/gluconeogenesis,pentose phosphate pathway, glycine, serine and threonine metabolism, as well as cysteine and methionine metabolism pathways. D-3-phosphoglyceric acid might be the key metabolite for tannic acid to inhibit MRSA. This study can provide insights for further elaborating the antibacterial mechanism of tannic acid.