乳酸杆菌胁迫抗性通常是用稀释平板菌落计数法来测定活菌数量从而计算存活率来表征的,该法存在检测周期较长和人为操作造成的误差较大的问题,该研究探究用分光光度计比浊法测定乳酸杆菌胁迫存活率的可行性。结果显示,在存活率为0.06~0.85时,发酵乳杆菌415酸胁迫存活率和取样时间点的生物量比之间的相关系数可达到0.997 1,并且这条酸胁迫标准方程可用于测定其他类型的胁迫(H2O2胁迫、胆盐胁迫、冷冻胁迫等)存活率,拟合存活率与真值之间的误差率均小于10%。以植物乳杆菌LGD为研究对象,验证了该比浊法也可以应用于测定其他乳酸杆菌胁迫存活率。分光光度计比浊法操作简单,测定结果与稀释平板菌落计数法所得结果存在良好的线性相关,检测时间较少,误差较小,有利于实现乳酸杆菌胁迫存活率的快速准确检测。
Traditional plate count method used to assess Lactobacillus stress resistance by determining the number of viable bacteria to calculate the survival rate has the problems of long detection cycle and large errors caused by human operation. To mitigate these drawbacks, the feasibility of determining the viability of Lactobacillus by the turbidimetric assay using spectrophotometer was evaluated. Experiments showed that the biomass ratio (biomass of the stress group to biomass of the control group) at sampling times had a significant linear correlation with the viability of L. fermentum 415 (ranged from 0.06-0.85) under acidic stress (R2 = 0.997 1). This standard equation of acidic stress could also be used to determine the viability under different types of stress (e.g., H2O2 stress, bile-salt stress, and cold stress) with error rates below 10%. It was confirmed that this method could also be used to evaluate the viabilities of another Lactobacillus strain, L. plantarum LGD, after exposure to various stresses. This light scattering assay required less detection time than that of plate culture, and the measurement result had a good linear correlation with the result obtained by the plate count method. Also, this method reduced the errors caused by dilution, therefore, facilitating rapid and accurate detection of viability of Lactobacillus under multiple stress.
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