电子束辐照抑制几种常见食源性致病菌生长的研究

Inhibition of Growth of Several Common Food Borne Pathogens by Electron Beam Irradiation

摘要:

为提高电子束辐照对食源性致病菌控制效果，以大肠埃希氏菌、鼠伤寒沙门氏菌、单核细胞增生李斯特氏菌、蜡样芽孢杆菌等4种常见致病菌为对象，通过分析D₁₀值、生长曲线、生物被膜和混菌培养中优势菌，研究了电子束辐照对致病菌生长的影响。结果表明，电子束辐照对4种致病菌具有很强的杀灭作用，D₁₀值范围为0.330~0.648 kGy，多次辐照可导致D₁₀值变小，致病菌对辐照耐受性降低。亚致死剂量电子束辐照可抑制致病菌生长，表现为延迟期延长，且稳定期菌落数量级水平低于对照，在较低温度15 ℃下表现更明显。不同致病菌间进行比较发现，大肠埃希氏菌对辐照最敏感，D₁₀值最低，延迟期滞后程度大于其他致病菌，而蜡样芽孢杆菌的辐照敏感度最低。4种致病菌辐照后共同培养时，蜡样芽孢杆菌在混合菌液中生长受到抑制，由33.49%下降至25.06%，其他3种致病菌百分比都较培养前有所增加。亚致死剂量电子束辐照可影响致病菌生物被膜形成，大肠埃希氏菌、蜡样芽孢杆菌辐照后成膜能力增强，而鼠伤寒沙门氏菌、单核细胞增生李斯特氏菌成膜能力减弱。

Abstract:

To improve the control effect of electron beam irradiation on foodborne pathogens, the effects of electron beam irradiation on the growth of pathogenic bacteria were studied by analysis of D₁₀ value, growth curve, biofilm formation and dominant bacteria in mixed culture of four common foodborne pathogens, including Escherichia coli, Salmonella typhimurium, Listeria monocytogenes and Bacillus cereus. The results showed that electron beam irradiation had strong disinfecting influence on these four pathogens and theD₁₀ values ranged from 0.330 kGy to 0.648 kGy. In addition, multiple irradiation could decrease the D₁₀ values, leading to the lower tolerance of pathogenic bacteria to irradiation. Sublethal dose electron beam irradiation could inhibit bacterial growth, which shoD₁₀wed longer lag phase and lower colony quantity level of stationary phase than that of the control. And this effect was especially significant at lower temperature of 15 ℃. Among different pathogenic bacteria, Escherichia coli was the most sensitive to irradiation, with the lowest D₁₀ valueand the greater lag degree of lag phase than other pathogenic bacteria, while Bacillus cereus was the least sensitive to irradiation. When the four pathogens were mixed and co-cultured after irradiation, the growth of Bacillus cereus irradiated by electron beam was inhibited and the percentage decreased from 33.49% to 25.06%, while the percentage of other three pathogens increased. Sublethal dose electron beam irradiation could affect the biofilm formation of pathogenic bacteria. After irradiation, the ability of forming biofilm of Escherichia coli and Bacillus cereus was enhanced, while that of Salmonella typhimurium or Listeria monocytogenes was weakened.