Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, 010018, China; Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, 010018, China.
Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, 010018, China; Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, 010018, China.
J Dairy Sci. 2021 Mar;104(3):2594-2605. doi: 10.3168/jds.2020-19303. Epub 2021 Jan 15.
In the ecosystem of spontaneously fermented cow milk, the characteristics and relationship of bacterial communities and nonvolatile components at different scales of geographical distances (provincial, county, and village levels) are unclear. Here, 25 sampling sites from Xin Jiang and Tibet, 2 provinces of China, were selected based on the distribution of spontaneously fermented cow milk and used for metagenomic and metabolomic analysis. At the provincial geographical distance, the same predominant species, Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus, were detected in Xin Jiang and Tibet. Further, the richness of the bacterial composition of samples from Tibet was higher than those from Xin Jiang; specifically, at the species level, 28 species were identified in Tibet samples but only 7 species in Xin Jiang samples. At the provincial geographical level, we detected significant differences in bacterial structure, shown in principal coordinate analysis plots, and significant differences (Simpson index) in bacterial diversity were also detected. However, at the county and village levels, no significant differences were detected in bacterial communities and diversity, but a difference in bacterial compositions was detectable. This indicates that bacterial communities and diversity of spontaneously fermented milk dissimilarity significantly increased with geographic distance. For the nonvolatile component profiles, the partial least squares discriminant analysis plot (RY > 0.5 and Q > 0.5 for the goodness-of-fit and predictive ability parameter, respectively) showed that samples from different geographical distances (provincial, county, and village) were all separated, which indicated that all the discriminations in nonvolatile components profiles were from different geographical distances. Investigating relationships between lactic acid bacteria and discriminatory nonvolatile components at the county level showed that 9 species were positively correlated with 16 discriminatory nonvolatile components, all species with low abundance rather than the predominant species L. delbrueckii ssp. bulgaricus and Strep. thermophilus, which indicates the importance of the selection of autochthonous nonpredominant bacteria.
在中国新疆和西藏两个省份的自然发酵牛乳生态系统中，细菌群落的特征和关系及其非挥发性成分在不同地理距离（省级、县级和村级）尺度上的特征和关系尚不清楚。在这里，我们根据自然发酵牛乳的分布，选择了来自新疆和西藏的 25 个采样点，进行了宏基因组和代谢组学分析。在省级地理距离上，在新疆和西藏都检测到了相同的优势种，即德氏乳杆菌保加利亚亚种和嗜热链球菌。此外，西藏样本的细菌组成丰富度高于新疆样本；具体而言，在物种水平上，在西藏样本中鉴定出 28 个物种，而在新疆样本中仅鉴定出 7 个物种。在省级地理水平上，我们检测到细菌结构的显著差异，表现在主坐标分析图上，并且还检测到细菌多样性的显著差异（辛普森指数）。然而，在县级和村级水平上，细菌群落和多样性没有显著差异，但可检测到细菌组成的差异。这表明，随着地理距离的增加，自然发酵牛乳的细菌群落和多样性的差异显著增加。对于非挥发性成分谱，偏最小二乘判别分析图（RY>0.5 和 Q>0.5 分别为拟合度和预测能力参数）表明，来自不同地理距离（省级、县级和村级）的样品都被分离，这表明非挥发性成分谱的所有判别都是来自不同的地理距离。在县级水平上调查乳酸菌与判别性非挥发性成分之间的关系表明，9 个物种与 16 个判别性非挥发性成分呈正相关，所有物种的丰度都较低，而不是优势种德氏乳杆菌保加利亚亚种和嗜热链球菌，这表明选择本土非优势菌的重要性。
