为建立金黄色葡萄球菌(Staphyloccocusaureus)活的非可培养(VBNC)状态的诱导条件模型,考察了温度、盐度和酸度3个因素对金黄色葡萄球菌细菌可培养数的影响,通过正交试验优化得到了VBNC状态的诱导条件,同时观察细菌可培养数的变化,建立了DNA结合染料叠氮溴乙锭(EMA)与qPCR技术相结合检测VBNC金黄色葡萄球菌的方法.实验结果表明:细菌可培养数受酸度的影响最大,VBNC状态的最佳诱导条件为菌液在含15%NaCl和0.3%乙酸的营养肉汤培养基中于4℃下培养12d;通过正交试验诱导后的不可培养菌可由EMA—qPCR方法有效检出,其与qPCR法的Ct值(荧光信号达到设定的阈值所经历的循环数)之差在1.29~8.56之间变化.
In order to establish a model for the determination of induction conditions of Staphyloccocus aureus in viable but non-culturable (VBNC) state and to reveal the effects of temperature, salt concentration and pH value on the cuhurable cell number of Staphyloccocus aureus, orthogonal experiments were carried out to optimize the induction conditions. Then, the cuhurable cells were monitored and a method based on the DNA-binding dye EMA (Ethidium Bromide Monoazide) and the qPCR technology was proposed to detect Staphyloccocus aureus in VBNC state. The results show that pH value greatly influences the culturable cell number, and that the cultivation in a nutrient broth medium with 15% (mass fraction) NaC1 and 0.3% (volume fraction) acetic acid at 4~C for 12d is best for the induction of Staphyloccocus aureus in VBNC state. Moreover, it is indicated that EMA-qPCR is an effective method to detect Staphyloccocus aureus in VBNC state under different induction conditions, with a Ct value improvement (cycle threshold) varying from 1.29 to 8.56.