Evaluation of a novel oxidative stress-adaptation method on membrane integrity, intracellular oxidation states, and survival of Bifidobacterium spp. during yoghurt fermentation and storage

This dataset describes the research conducted in the study, “Survival of Oxidative Stress-Adapted <em>Bifidobacterium</em> spp. in Yoghurt,” which consisted of three research phases. During phase 1, cultures of <em>B. bifidum, B. breve</em>, and <em>B. animalis</em> subsp. <em>animalis</em> were subjected to a sublethal (0.4 mM) H₂O₂ treatment followed by exposure to lethal (1 mM) H₂O₂ treatments for three successive generations. Phase 2 tested the H₂O₂-treated <em>Bifidobacterium</em> cells against previously lethal oxidative stress conditions. Finally, phase 3 evaluated the survival of the stress-adapted <em>Bifidobacterium</em> spp. during yoghurt fermentation and storage (28 days; analysis on days 0, 7, 14, 21, and 28).
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The dataset files are organised by chapters: Chapters 2, 4, 5, and 6. The fluorescent histograms show the effects of the H₂O₂ treatments on the membrane integrity and intracellular oxidation states of the <em>Bifidobacterium</em> cells. SEM and TEM images indicate morphological and ultrastructural adaptations resulting from the H₂O₂ treatments. Furthermore, the fluorescent biplots illustrate both the membrane integrity and intracellular oxidation responses of the H₂O₂-treated <em>Bifidobacterium</em> cells following a lethal oxidative stress challenge. The tables display growth kinetics and maximum population density, along with the statistical analysis of the stress-adapted <em>Bifidobacterium</em> spp. under varying conditions of oxidative stress (0, 0.1, and 1 mM H₂O₂). Scanning and transmission electron microscopy (SEM and TEM) images also reflect the morphological and ultrastructural adaptations of stress-adapted <em>Bifidobacterium</em> spp. in response to lethal oxidative stress.
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The analyses conducted during the yoghurt shelf-life study are presented in various figures and tables within the dataset. The figures show pH measurements (at 0, 1, 2, 3, and 3.4 hours) and <em>Bifidobacterium</em> spp. viability levels (before and after fermentation), along with the statistical analyses in the relevant tables. Physicochemical analyses, including pH, titratable acidity (TA), oxidation-reduction potential (ORP), and % syneresis, are shown during refrigerated storage on days 0, 7, 14, 21, and 28. Bacteriological analyses, such as standard plate counts and viability proportion index (VPI₂₈), are also presented, along with the respective statistical analyses for each yoghurt. Principal component analysis (PCA) was conducted on data collected during the shelf-life stage.
The dataset also includes the determination of bacterial viability using a novel propidium monoazide quantitative polymerase chain reaction (PMAxx-qPCR) method, with measurements on days 0 and 28 of shelf-life. Relevant tables and figures show the melt curve, standard curve, simple linear regression, and Bland-Altman method of comparison (% Difference vs. Average) of the PMAxx-qPCR method compared to the standard plate count method, along with the statistical analyses of bacterial viability measured by the PMAxx-qPCR method. Finally, a summary table linking the yoghurt shelf-life study to the thesis' problem statement is shown.

本数据集对应题为《酸奶中适应氧化应激的双歧杆菌属（Bifidobacterium）菌株存活特性》的研究，该研究包含三个实验阶段。第一阶段中，将两歧双歧杆菌（B. bifidum）、短双歧杆菌（B. breve）以及动物双歧杆菌动物亚种（B. animalis subsp. animalis）的培养物先经亚致死浓度（0.4 mM）过氧化氢（H₂O₂）处理，随后连续三代暴露于致死浓度（1 mM）的过氧化氢环境中。第二阶段测试经过氧化氢处理的双歧杆菌细胞对此前认定为致死剂量的氧化应激条件的耐受能力。第三阶段则评估适应氧化应激的双歧杆菌属菌株在酸奶发酵及冷藏储存（28天，分别于第0、7、14、21、28天进行检测）过程中的存活情况。
数据集文件按章节分类，涵盖第2、4、5、6章。荧光直方图展示了过氧化氢处理对双歧杆菌细胞膜完整性及细胞内氧化状态的影响。扫描电子显微镜（SEM）与透射电子显微镜（TEM）图像则呈现了过氧化氢处理后菌株产生的形态学与超微结构适应性变化。此外，荧光双标图可直观展现经过氧化氢处理的双歧杆菌细胞在遭受致死氧化应激挑战后的细胞膜完整性与细胞内氧化应激响应情况。表格数据则包含生长动力学与最大种群密度，以及不同氧化应激浓度（0、0.1、1 mM H₂O₂）条件下适应应激的双歧杆菌属菌株的相关统计分析。扫描及透射电子显微镜图像同样反映了适应氧化应激的双歧杆菌属菌株在应对致死氧化应激时的形态与超微结构适应性改变。
酸奶货架期研究中的各项分析结果均收录于数据集的各类图表与表格中。相关图表展示了发酵前后的pH值检测结果（于0、1、2、3及3.4小时采样）与双歧杆菌属菌株的活菌水平，配套表格则包含对应的统计分析内容。理化分析指标包括pH值、滴定酸度（TA）、氧化还原电位（ORP）以及乳清析出率（%），相关数据采集于冷藏储存的第0、7、14、21、28天。细菌学分析则包含标准平板计数法与活菌比例指数（VPI₂₈）的测定结果，同时附有每种酸奶对应的统计分析数据。货架期阶段的数据还进行了主成分分析（PCA）。
数据集还包含采用新型叠氮溴化丙锭定量聚合酶链式反应（PMAxx-qPCR）法测定细菌活菌量的相关内容，检测时间为货架期的第0天与第28天。相关表格与图表展示了该PMAxx-qPCR法与标准平板计数法的熔解曲线、标准曲线、简单线性回归结果以及Bland-Altman比较分析法（差异百分比与平均值对比），同时包含采用PMAxx-qPCR法测定细菌活菌量的统计分析数据。最后，数据集附有一张汇总表格，将酸奶货架期研究与本学位论文的问题陈述进行关联对应。