臭氧水与副干酪乳杆菌Z21联合处理对绿豆芽中大肠杆菌O157:H7的抑制机制

为研究臭氧水联合副干酪乳杆菌Z21发酵上清液对绿豆芽中大肠杆菌O157:H7的杀菌效果、细胞结构影响和生物膜清除作用，本实验对人工污染大肠杆菌O157:H7的绿豆芽进行联合处理，选出最优的杀菌条件，采用流式细胞仪、扫描电镜、傅里叶红外光谱（Fourier-transform infrared spectroscopy，FT-IR）、拉曼光谱分析臭氧水联合Z21发酵上清液的杀菌机制；通过菌落计数及胞外聚合物分析，研究了臭氧水联合Z21发酵上清液对大肠杆菌O157:H7生物膜的清除效果。结果表明，1.5 mg/L臭氧水联合10%（v/v）Z21发酵上清液处理对大肠杆菌O157:H7杀菌效果最佳，菌落总数减少了2.81 lg CFU/g；与对照组相比，联合处理破坏了大肠杆菌O157:H7细胞壁和细胞膜中的多糖，脂质和蛋白质结构，增加了细胞膜的通透性，改变了菌体形态。联合处理对生物膜有良好的清除效果，显著降低了生物膜的胞外聚合物含量（P<0.05）。本研究为大肠杆菌生物膜的清除及农产品防腐保鲜提供了理论依据。

The Antibacterial Mechanism of Ozone Water Combined with Lactobacillus paracasei Z21 on E.coli O157:H7 in Mung Bean Sprouts

To explore the bactericidal effect, cell structure and biofilm removal mechanism of ozone water combined with Lactobacillus paracasei Z21 fermented supernatant on E. coli O157:H7 in mung bean sprouts, this experiment combined treatment of artificially contaminated E. coli O157:H7 to select the optimal bactericidal conditions. The bactericidal mechanism of ozone water combined with Z21 supernatant was studied by flow cytometry, scanning electron microscopy, Fourier transform infrared spectroscopy (FT-IR) and raman spectroscopy. The effect of ozone water combined with Z21 fermented supernatant on E. coli O157:H7 biofilm was studied by colony counting and extracellular polymer analysis. The results showed that 1.5 mg/L ozone water combined with 10% (V/V) Z21 fermented supernatant had the best bactericidal effect on E. coli O157:H7, and the total number of bacteria decreased by 2.81 lg CFU/g. Compared with the control group, the combined treatment destroyed polysaccharides, lipid and protein structures in the cell walls and membranes of E. coli O157:H7, increased the permeability of cell membrane, and changed the morphology. The combined treatment presented a strong removal effect on biofilm, and the extracellular polymer content of the biofilm was significantly reduced (P<0.05). This study could provide a theoretical basis for the removal of Escherichia coli biofilm and preservation of agricultural products.