Abstract：
The purpose of this study was to reveal the antibacterial activity and mechanism of Polygonatum sibiricum extract (PSE) against Bacillus cereus and further analyze the application of PSE in pasteurized milk (PM). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values and growth curve analysis were used to evaluate the antibacterial activity of PSE against B. cereus. The changes in contents of intracellular adenosine 5\'-triphosphate (ATP) and reactive oxygen species (ROS), activities of β-galactosidase, adenosine triphosphatase (ATPase) and alkaline phosphatase (AKP), cell membrane potential, protein and nucleic acid leakage, and cell morphology were used to reveal the antibacterial mechanism. The effects of PSE on viable count and sensory evaluation of PM during storage were analyzed. The results showed that the MIC and MBC values of PSE against B. cereus were 2 and 4 mg/mL, respectively. Growth curve analysis showed that PSE with a concentration of 2 MIC could completely inhibit the growth of B. cereus. After treatments with PSE, the levels of intracellular ATP and ROS, and activities of β-galactosidase, ATPase and AKP of B. cereus were significantly reduced (p < 0.05). Cell membrane was depolarized, amounts of protein and nucleic acid leakage were significantly increased (p < 0.05), and cell morphology was destroyed. Furthermore, PSE significantly reduced the viable count of B. cereus in PM and improved the sensory quality of PM during storage (p < 0.05). Together, our findings suggested that PSE had the desired effect as a natural preservative applied in PM.
摘要：
本研究旨在揭示黄精提取物(PSE)对蜡样芽孢杆菌的抑菌活性及作用机理,并进一步分析PSE在巴氏杀菌乳(PM)中的应用。用最小抑菌浓度(MIC)和最小杀菌浓度(MBC)值和生长曲线分析评价PSE对蜡样芽孢杆菌的抗菌活性。细胞内腺苷5'-三磷酸（ATP）和活性氧（ROS）含量的变化，β-半乳糖苷酶的活性，腺苷三磷酸酶（ATPase）和碱性磷酸酶（AKP），细胞膜电位，蛋白质和核酸泄漏，和细胞形态来揭示抗菌机制。分析了PSE对贮藏期间PM的活菌数和感官评价的影响。结果表明，PSE对蜡样芽孢杆菌的MIC和MBC值分别为2和4mg/mL，分别。生长曲线分析表明，浓度为2MIC的PSE可以完全抑制蜡样芽孢杆菌的生长。用PSE治疗后，细胞内ATP和ROS的水平，和β-半乳糖苷酶的活性，蜡样芽孢杆菌的ATP酶和AKP显著降低(p<0.05)。细胞膜去极化，蛋白质和核酸泄漏量显著增加(p<0.05)，细胞形态被破坏。此外，PSE显着降低了PM中蜡样芽孢杆菌的活菌数，并改善了PM在存储过程中的感官质量（p<0.05）。一起,我们的研究结果表明，PSE作为天然防腐剂应用于PM具有预期的效果。
