运用Real-time PCR方法建立大肠杆菌O157:H7生长预测模型

Predictive Model of Escherichia coli O157:H7 Built by Real-time PCR

运用Real-time PCR方法建立大肠杆菌O157:H7不同温度(10,15,20,25,30℃)条件下的初级生长动力模型,包括修正Gompertz模型、Logistic模型。结果表明,两种模型均能很好拟合两种计数方法,得到大肠杆菌O157:H7在不同温度条件下生长曲线;每条曲线存在明显的迟滞期、对数期和稳定期,且温度对微生物的生长速率和迟滞期有明显影响,随温度的升高生长速率显著增加而迟滞期明显缩短。通过相关系数(R2)、均方根误差(MSE)、偏差因子(Bf)和准确因子(Af)等评估模型的准确性,R2均≥0.99;MSE值均小于0.1 lg cfu/m L,模型拟合程度较好。偏差因子Bf值和准确因子Af值均在可接受的范围内,模型准确性高。通过与传统培养计数得到的预测模型进行比较,运用Real-time PCR方法建立的模型与传统方法建立模型无显著差别,能较好地预测大肠杆菌O157:H7的生长情况,解决了传统预测模型耗时、耗力等问题。

This study developed the primary growth models of Escherichia coli 0157：H7 built by Real-time PCR under different temperature （10, 15, 20, 25, 30℃）, including modified Gompertz model and Logistic model. The re- suits showed that the two models could both finely fit the growth curves of E. coli O157：H7 under different temperatures by Real-time PCR method and traditional plate culture method. Every curve showed obvious lag phase, logarithmic phase and stable phase, and the growth rate increased significantly and the period of lag phase shortens quickly as the temper- ature was higher. Through correlation coefficient （R2）, root mean square error （MSE）, bias factor（Bf） and accuracy fac- tor （Af）, we assessed the accuracy of the models. The values of R2 are generally above 0.99 and MSE are less than 0.1 lg cfu/mL which showed that the fitting degree of models is appropriate. The Bf values and the Af values are all in the acceptable scope, so the models have higher accuracy. Compared with the models based on traditional plate culture method, the models established by Real time PCR method had no significant difference, which can be used to predict the growth of E. coli O157：H7, and solve the problems of traditional predictive models such as labor-intensive and time-consuming.