基于OD-TTD法构建金黄色葡萄球菌生长模型的研究

Establishment of Growth Model of Staphylococcus aureus Based on OD-TTD

摘要:

本文应用OD-TTD法测定金黄色葡萄球菌的生长速率和迟滞期，并在此基础上构建其生长模型。以金黄色葡萄球菌CMCC(B)26003为实验菌株，将梯度稀释的菌液于96孔细胞培养板中培养，实时测定各菌液的OD值。根据达到特定OD值所需的时间（times to detection，TTD）与起始菌数（N0）的线性关系和OD达到特定值时的菌数（Nd），计算生长速率（μ）和迟滞期（λ），然后选择合适的模型拟合生长数据。结果得出：TTD=-154.86N0+1202.3，R2=0.9997（OD=0.1），计算出μ为0.0064 log [cfu/(mL?min)]，λ为7.8 min。根据Gompertz、Baranyi、Logistic和3-phase linear（3PLM）模型推算TTD值。结果表明3PLM模型推导结果与实测值基本吻合，因此最适合构建生长模型。此外，对比平板法和OD-TTD法，发现生长速率值两者差别不大，但迟滞期值则前者远比后者大。因此，在OD-TTD法基础上采用3PLM模型可以快速简便地构建金黄色葡萄球菌生长模型，但是迟滞期的测定结果仍存在不确定性。

Abstract:

The growth model of Staphylococcus aureus CMCC (B) 26003 based on growth rates and lag time calculated by OD-TTD data was studied in this paper. The culture was serial diluted and static cultivated in 96 pores micro-array plate at 37 ℃. When the linear relationship between the initial inoculums (N0) and the time to detection criterion of OD at specific value (TTD) was available, the growth rate could be calculated. If the viable count from well with OD at detection value (Nd) was known, the lag time could also be obtained. Then a suitable model was selected to fit the growth data. The linear relationship between TTD and N0 as follows: TTD=-154.86 N0+1202.3, R2 = 0.9997 (OD = 0.1). The growth rate of 0.0064 log [cfu/(mL?min)] (μ) and lag time of 7.8 min (λ) were obtained by the formula. If the information of μ,λ,N0, Nmax and Nd were available, and TTD could be calculated by Gompertz, Baranyi, Logistic and 3-phase linear (3PLM) model. In addition, the calculated value by 3PLM was congruent with the observed value. The growth rate from OD-TTD was almost equal with that from viable plate count, and the lag time from viable plate count was bigger than that from OD-TTD. Therefore, 3PLM based on OD-TTD was suitable to construct the growth model of Staphylococcus aureus, but the lag time from OD-TTD was uncertain yet.