Abstract This study was conducted to analyze the antimicrobial activity of olive oil polyphenols extract (OOPE) against Cronobacter sakazakii. The antimicrobial effect was evaluated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values, and survival of bacteria after treatments with OOPE in sterile normal saline (NS) and Luria-Bertani (LB) broth. The changes in intracellular ATP concentration, cell membrane potential, content of bacterial protein, and cell morphology were analyzed to reveal possible mechanism of action. The results showed that the MICs and MBCs of OOPE against C. sakazakii strains ranged from 0.625 to 1.25 mg/mL, and 1.25–2.50 mg/mL, respectively. Approximately 8 log CFU/mL of C. sakazakii was completely inactivated after a treatment with 1 MIC of OOPE in NS at 37 °C for 3 h, and in LB broth at 37 °C for 10 h. The mechanism of action of OOPE against C.sakazakii was associated with reduction of intracellular ATP concentrations, cell membranes depolarization, leakage of cytoplasm, decrease of bacterial protein content and leakage of cytoplasm. Therefore, our findings provided a theoretical possibility that OOPE can be used as a natural food preservative or bactericide to reduce the food safety problems caused by C. sakazakii strains in food industries as well as food processing environments.

中文翻译：

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橄榄油多酚提取物对坂崎克罗诺杆菌的抗菌活性及作用机制

摘要 本研究旨在分析橄榄油多酚提取物 (OOPE) 对坂崎克罗诺杆菌的抗菌活性。通过最小抑菌浓度 (MIC) 和最小杀菌浓度 (MBC) 值以及在无菌生理盐水 (NS) 和 Luria-Bertani (LB) 肉汤中用 OOPE 处理后细菌的存活率来评估抗菌效果。分析细胞内ATP浓度、细胞膜电位、细菌蛋白质含量和细胞形态的变化以揭示可能的作用机制。结果表明，OOPE 对阪崎肠杆菌菌株的 MIC 和 MBC 分别为 0.625 至 1.25 mg/mL 和 1.25-2.50 mg/mL。在 37 °C 下用 1 MIC 的 OOPE 在 NS 中处理 3 小时后，大约 8 log CFU/mL 的 C. sakazakii 被完全灭活，并在 37 °C 的 LB 肉汤中培养 10 小时。OOPE对C.sakazakii的作用机制与细胞内ATP浓度降低、细胞膜去极化、细胞质渗漏、细菌蛋白含量减少和细胞质渗漏有关。因此，我们的研究结果提供了理论上的可能性，即 OOPE 可用作天然食品防腐剂或杀菌剂，以减少食品工业和食品加工环境中由阪崎肠杆菌引起的食品安全问题。