【作者】 陈秋云；

【导师】 韩北忠；

【作者基本信息】 中国农业大学 ， 食品科学与工程， 2004， 硕士

【副题名】食源性病原菌生物被膜在不锈钢表面的形成过程及其对杀菌剂的敏感性

【摘要】 本实验研究食源性病原菌(金黄色葡萄球菌，沙门氏菌)生物被膜在不锈钢表面形成过程及其对常见消毒剂(次氯酸钠，二氧化氯)的敏感性，为在食品加工过程中对加工设备的不锈钢表面清洗消毒提供了试验数据，并为食品加工中对其他表面的清洗消毒提供参考。 通过建立食源性病原菌(金黄色葡萄球菌和沙门氏菌)生物被膜模型，测定它们在不锈钢表面形成生物被膜的生长曲线，同时结合金黄色葡萄球菌和沙门氏菌的生长曲线，分析食源性病原菌生物被膜在不锈钢表面的形成过程；采用扫描电镜(scanning electron microscope，SEM)确认生物被膜形态并采用计算机图形处理系统进行图形分析；采用平板擦拭法(plating ofswabbing)测定生物被膜中存活细菌数：采用试管稀释法测定常见杀菌剂对生物被膜及其菌悬液的最低清除浓度。 金黄色葡萄球菌和沙门氏菌分别在大豆胰酶肉汤(Trypease soy broth，TSB)中与不锈钢片共同培养7d后可形成稳定的生物被膜，细菌密度约达到10~6cfu／cm~2。用扫描电镜可见金黄色葡萄球菌生物被膜细菌呈球状，沙门氏菌生物被膜细菌呈杆状，周围分布凹凸不平的块状物，菌体周围和相互间以粘稠的粘液丝相连，借助于粘液样物使细菌之间相互连接形成生物被膜。 有效氯浓度、TSB培养基浓度、作用时间均能影响杀菌剂的杀菌效果。当不含TSB培养基时，消毒剂(次氯酸钠和二氧化氯)有效氯浓度50～100mg／l作用时间超过20min，可使10~6cfu／ml的菌悬液杀菌率达到100％，次氯酸钠和二氧化氯有效氯浓度100～150mg／l作用时间超过20min，可使细菌密度为10~6cfu／cm~2的生物被膜杀菌率达到100％。当在3.0％(w／v)TSB中，次氯酸钠和二氧化氯有效氯浓度大于150mg／l作用30 min后，可使10~6cfu／ml的菌悬液杀菌率达到100％，而在有效氯浓度超过400 mg／l作用30 min后，才使细菌密度为10~6cfu／cm~2的生物被膜杀菌率达到100％。实验中，二氧化氯对菌悬液及其生物被膜的杀菌效果、灭菌速度上略优于次氯酸钠。更多还原

【Abstract】 Biofilm formation of foodborne pathogenic bacteria on stainless steel surface and their sensitivity to disinfectants were studied, which could be used in cleaning and sterilizing equipments during food processing.After Measuring the growth curves of foodborne pathogenic bacteria biofilms by establishing their biofilms modeling on stainless steel surface and the growth curves of foodborne pathogenic bacteria, then analysised the biofilm formation of foodborne pathogenic bacteria biofilms on stainless steel surface. The samples were then detected by scanning electron microscopy (SEM), the optical density of bacterial biofilm was determined by using computer image analysis system. The viable counts of bacteria in biofilm were detected by the method of plating of swabbing. The minimal eradication concentration (MEC) of disinfectants for biofilm and suspensions was determined by test tube dilution method.The foodborne pathogenic bacteria biofilms on stainless steel surface were obtained after incubation in trypease soy broth (TSB) for 7 d with a cell density of 106 cfu/cm2. The SEM graphs showed that bacteria of Salmonella sp. (AS 1.1552) were bacillus and Staphylococcus aureus (AS 1.89) were coccus, which surrounded by accidented material and the bacteria were connected each other by slimes to form biofilm.The factors about concentration of available chlorine, concentration of TSB culture medium and contact time of disinfectant could influence the germicidal efficacy. The results showed that disinfectants (soclium hypochlorite and chlorine dioxide) containing available chlorine 50~100 mg/l with more 20 min contact time killed 100% of suspensions with a cell density of 106 cfu/ml and disinfectants containing available chlorine 100-150 mg/1 with more 20 min contact time killed 100% of biofilm with a cell density of 106 cfu/cm2 in 0% (w/v) TSB culture medium. Disinfectants containing available chlorine 150 mg/1 with 30 min contact time killed 100% of suspensions with a cell density of 10 cfu/ml and disinfectants containing available chlorine 400mg/l with 30 min contact time killed 100% of biofilm with a cell density of 106 cfu/cm2 in 3.0% (w/v) TSB culture medium. Chlorine dioxide was better than sodium hypochlorite in germicidal efficacy.更多还原