Mogotsi Lerato, De Smidt Olga, Venter Pierre, Groenewald Willem
Unit for Applied Food Science and Biotechnology, Central University of Technology, Free State, P.O. Box 20539, Bloemfontein 9300, South Africa.
Fonterra Co-Operative Group Limited, Private Bag 11029, Palmerston North 4442, Dairy Farm Road 1, Palmerston North, New Zealand.
ScientificWorldJournal. 2014;2014:135856. doi: 10.1155/2014/135856. Epub 2014 May 25.
The influence of sublethal concentrations of two sanitizers, liquid iodophor and liquid hypochlorite (LH), on the growth rates and toxicity of food-borne pathogenic Escherichia coli strains grown in the presence of spoilage yeast Zygosaccharomyces bailii was assessed. When grown in combination with Z. bailii both E. coli O113 and E. coli O26 exhibited slower growth rates, except when E. coli O113 was grown in combination with Z. bailii at 0.2% LH. The growth rate of Z. bailii was not impacted by the addition of the sanitizers or by communal growth with E. coli strains. LAL and IL-6 results indicated a decrease in toxicity of pure E. coli cultures with comparable profiles for control and sanitizer exposed samples, although the LAL assay proved to be more sensitive. Interestingly, pure cultures of Z. bailii showed increased toxicity measured by LAL and decreased toxicity measured by IL-6. LAL analysis showed a decrease in toxicity of both E. coli strains grown in combination with Z. bailii, while IL-6 analysis of the mixed cultures showed an increase in toxicity. The use of LAL for toxicity determination in a mixed culture overlooks the contribution made by spoilage yeast, thus demonstrating the importance of using the appropriate method for toxicity testing in mixed microbe environments.
评估了两种消毒剂（碘伏溶液和次氯酸钠溶液（LH））的亚致死浓度对在腐败酵母拜耳接合酵母存在下生长的食源致病性大肠杆菌菌株生长速率和毒性的影响。当与拜耳接合酵母共同培养时，除了大肠杆菌O113在0.2% LH条件下与拜耳接合酵母共同培养外，大肠杆菌O113和大肠杆菌O26的生长速率均较慢。拜耳接合酵母的生长速率不受消毒剂添加或与大肠杆菌菌株共同生长的影响。鲎试剂法（LAL）和白细胞介素-6（IL-6）的结果表明，纯大肠杆菌培养物的毒性降低，对照样品和暴露于消毒剂的样品具有可比的特征，尽管鲎试剂法被证明更敏感。有趣的是，拜耳接合酵母的纯培养物通过鲎试剂法测得的毒性增加，而通过IL-6测得的毒性降低。鲎试剂法分析表明，与拜耳接合酵母共同培养的两种大肠杆菌菌株的毒性均降低，而混合培养物的IL-6分析表明毒性增加。在混合培养物中使用鲎试剂法测定毒性忽略了腐败酵母的作用，从而证明了在混合微生物环境中使用适当的毒性测试方法的重要性。
