复配天然防腐剂对贝莱斯芽孢杆菌和鲍曼不动杆菌的抑菌机制及其稳定性研究OA

This study investigated the mechanism and stability of a compounded natural preservative against Bacillus velezensis and Acinetobacter baumannii.The antibacterial mechanism was explored by assessing changes in cell membrane permeability,cell wall integri-ty,and antioxidant enzyme activity,combined with scanning electron microscopy to observe bacterial ultrastructure.Additionally,the effects of temperature,pH,and salt mass concentration on preservative stability were examined.The results demonstrated that the com-pounded natural preservative disrupts cell membrane permeability and cell wall integrity,thereby inducing massive leakage of proteins and nucleic acids.Regarding metabolic regulation,after 4 h of treatment,catalase activity in the two bacteria decreased by 38.95％and 26.69％,respectively,compared to the non-preservative control group,while superoxide dismutase activity increased by 35.27％and 20.59％,respectively,indicating induced oxidative stress imbalance.SEM images revealed pore formation on bacterial surfaces and leak-age of cellular contents,with damage severity exceeding that observed in chemical preservative-treated groups.Stability tests showed that the preservative maintained excellent thermal stability within the range of-20℃to 80℃,retaining over 83％antibacterial activity even after 30 minutes of treatment at 100 ℃.Antibacterial efficacy was not significantly affected(P＞0.05)at pH of 3-5 and 7.Similarly,salt mass concentrations ≤4 mg/mL had no significant impact on activity(P＞0.05).In conclusion,the compounded natural preservative achieves highly effective antibacterial activity by disrupting bacterial structures and interfering with metabolism,and it exhibits high tem-perature and acid resistance,providing a theoretical basis for the development of natural preservation technology for pickled mustard.