Technology Innovation Research Division, World Institute of Kimchi, Gwangju, Republic of Korea.
Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, Republic of Korea.
Microbiol Spectr. 2022 Aug 31;10(4):e0162522. doi: 10.1128/spectrum.01625-22. Epub 2022 Jul 25.
Acid tolerance is an important feature of probiotic development. It is one of the factors underlying the beneficial effects of probiotics in the intestine. However, the methods used by different researchers to test acid tolerance vary, causing confusion in the interpretation of the results. Therefore, in this study, we determine the optimal conditions for the acid tolerance test using response surface methodology. The factors of pH (2.5 to 3.5), exposure time (1 to 2 h), and pepsin (presence or absence) were used as independent variables, and the survival rates of seven strains (Lacticaseibacillus casei KACC 12413, Lactiplantibacillus plantarum KACC 15357, Limosilactobacillus fermentum KACC 11441, WCFS1, Lacticaseibacillus rhamnosus GG, KCTC 21024, and WiKim 0112) known to have probiotic properties were used as dependent variables. The results of the analysis of variance (ANOVA) indicated that the pH value and exposure time in acidic environments significantly affected the acid tolerance test model, and their interaction also had an effect ( < 0.05). Using the ANOVA results, the condition of the acid tolerance test was optimized with a target of an 85% survival rate for each strain. The optimized conditions of the acid tolerance test were as follows: pH 2.92, exposure time of 1.73 h, and presence of pepsin and pH 3, exposure time of 1.98 h, and absence of pepsin. These results can optimize strain selection with rigorous acid tolerance without confusion by unifying the conditions for the acid tolerance test. The acid tolerance test, which is the first step in selecting probiotics, is not standardized and can often cause confusion in the interpretation of results. Thus, in the present study, we optimized the conditions for the acid tolerance test using response surface methodology. These optimized conditions can be used to screen for strains with acid tolerance.
耐酸性是益生菌开发的重要特征。它是益生菌在肠道中发挥有益作用的基础因素之一。然而，不同研究人员用于测试耐酸性的方法不同，导致结果的解释出现混淆。因此，在本研究中，我们使用响应面法确定耐酸性测试的最佳条件。使用 pH（2.5 至 3.5）、暴露时间（1 至 2 小时）和胃蛋白酶（存在或不存在）作为自变量，将七种具有益生菌特性的菌株（鼠李糖乳杆菌 KACC 12413、植物乳杆菌 KACC 15357、发酵乳杆菌 KACC 11441、WCFS1、鼠李糖乳杆菌 GG、KCTC 21024 和 WiKim 0112）的存活率作为因变量。方差分析（ANOVA）的结果表明，在酸性环境中 pH 值和暴露时间显著影响耐酸性测试模型，它们的相互作用也有影响（<0.05）。使用 ANOVA 结果，以每种菌株 85%的存活率为目标优化耐酸性测试条件。优化后的耐酸性测试条件如下：pH 值 2.92，暴露时间 1.73 小时，存在胃蛋白酶；pH 值 3.0，暴露时间 1.98 小时，不存在胃蛋白酶。这些结果可以通过统一耐酸性测试条件来优化严格耐酸性的菌株选择，避免结果解释出现混淆。作为选择益生菌的第一步，耐酸性测试尚未标准化，经常导致结果解释出现混淆。因此，在本研究中，我们使用响应面法优化了耐酸性测试的条件。这些优化条件可用于筛选具有耐酸性的菌株。
