Key Laboratory of Dairy Science, Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin 150030, China; College of Food and Bioengineering, Henan University of Science and Technology, Luoyang 471023, China.
College of Food and Bioengineering, Henan University of Science and Technology, Luoyang 471023, China.
J Dairy Sci. 2019 May;102(5):3894-3902. doi: 10.3168/jds.2018-15184. Epub 2019 Mar 7.
This study was conducted to analyze the antibacterial effect of olive oil polyphenol extract (OOPE) against vegetative cells of Bacillus cereus isolated from raw milk and reveal the possible antibacterial mechanism. The diameter of inhibition zone, minimum inhibitory concentration, minimum bactericidal concentration, and survival counts of bacterial cells in sterile normal saline and pasteurized milk were used to evaluate the antibacterial activity of OOPE against B. cereus vegetative cells. The changes in intracellular ATP concentration, cell membrane potential, content of bacterial protein, and cell morphology were analyzed to reveal possible mechanisms of action. Our results showed the diameter of inhibition zone, minimum inhibitory concentration, and minimum bactericidal concentration of OOPE against B. cereus vegetative cells were 18.44 ± 0.55 mm, 0.625 mg/mL, and 1.25 mg/mL, respectively. Bacillus cereus GF-1 vegetative cells were decreased to undetectable levels from about 8 log cfu/mL after treatments with 0.625 mg/mL of OOPE in normal saline at 30°C for 3 h and in pasteurized milk at 30°C for 10 h. The antibacterial mechanisms of OOPE against B. cereus GF-1 vegetative cells may be due to the reduction of intracellular ATP concentrations, cell membrane depolarization, decrease of bacterial protein content, and leakage from cytoplasm. These findings illustrated that OOPE could be used to prevent the growth of contaminating B. cereus cells in dairy products.
本研究旨在分析橄榄油多酚提取物（OOPE）对生牛乳中分离的蜡样芽孢杆菌营养细胞的抗菌作用，并揭示其可能的抗菌机制。采用抑菌圈直径、最小抑菌浓度（MIC）、最小杀菌浓度（MBC）以及无菌生理盐水和巴氏杀菌乳中细菌细胞存活数来评价 OOPE 对蜡样芽孢杆菌营养细胞的抗菌活性。分析细胞内 ATP 浓度、细胞膜电位、细菌蛋白含量和细胞形态的变化，以揭示其可能的作用机制。结果表明，OOPE 对蜡样芽孢杆菌营养细胞的抑菌圈直径、MIC 和 MBC 分别为 18.44 ± 0.55 mm、0.625 mg/mL 和 1.25 mg/mL。在 30°C 生理盐水和 30°C 巴氏杀菌乳中，用 0.625 mg/mL 的 OOPE 处理 3 h 后，蜡样芽孢杆菌 GF-1 营养细胞数从约 8 log cfu/mL 减少到不可检测水平；用 0.625 mg/mL 的 OOPE 处理 10 h 后，蜡样芽孢杆菌 GF-1 营养细胞数也从约 8 log cfu/mL 减少到不可检测水平。OOPE 对蜡样芽孢杆菌 GF-1 营养细胞的抗菌机制可能是由于细胞内 ATP 浓度降低、细胞膜去极化、细菌蛋白含量减少以及细胞质渗漏。这些发现表明，OOPE 可用于防止乳制品中污染的蜡样芽孢杆菌细胞的生长。
