传统的发酵乳是通过接种过程生产的,该过程涉及故意引入已经适应并在连续世代中延续的微生物。然而,在实验室环境下长期接种发酵过程中,传统发酵乳微生物群的变化仍不清楚。在这项研究中,我们从中国西藏(3种kurut产品)和新疆(2种tarag产品)的5个不同县收集了5种传统发酵乳样品,作为9个月连续接种发酵实验的发酵剂培养物。我们分析了采集样本的微生物群落的种群间和种群内的变化,代表他们的宏观多样性和微观多样性,使用鸟枪宏基因组测序。在所有样品中,我们总共获得了186个高质量的宏基因组组装基因组,包括7属13种,相对丰度超过1%。这些基因组中的大多数被注释为瑞士乳杆菌(60.46%),厄兰肠球菌(9.52%),和发酵肝菌(6.23%)。我们观察到5种初始接种体之间的物种组成和丰度存在显着差异。在长期接种发酵过程中,我们发现物种多样性总体呈上升趋势,composition,发酵乳细菌宏基因组中碳水化合物代谢模块编码基因的丰度,而发酵乳病毒表现出相对较窄的变化范围。瑞士乳杆菌,传统发酵奶中的优势物种,在长期接种发酵过程中表现出很高的稳定性。我们的研究为传统发酵乳的工业化生产提供了有价值的见解。
Traditional fermented milks are produced through an inoculation process that involves the deliberate introduction of microorganisms that have been adapted and perpetuated across successive generations. However, the changes in the microbiota of traditional fermented milk during long-term inoculation fermentation in a laboratory environment remain unclear. In this study, we collected 5 samples of traditional fermented milk samples from 5 different counties in Tibet (3 kurut products) and Xinjiang (2 tarag products) of China, which served as starter cultures for a 9-mo continuous inoculation fermentation experiment. We analyzed the inter- and intra-population variations in the microbial communities of the collected samples, representing their macrodiversity and
microdiversity, using shotgun metagenomic sequencing. Across all samples, we obtained a total of 186 high-quality metagenomic-assembled genomes, including 7 genera and 13 species with a relative abundance of more than 1%. The majority of these genomes were annotated as Lactobacillus helveticus (60.46%), Enterococcus durans (9.52%), and Limosilactobacillus fermentum (6.23%). We observed significant differences in species composition and abundance among the 5 initial inoculants. During the long-term inoculation fermentation, we found an overall increasing trend in species diversity, composition, and abundances of carbohydrate metabolism module-encoding genes in the fermented milk bacterial metagenome, while the fermented milk virome exhibited a relatively narrow range of variation. Lactobacillus helveticus, a dominant species in traditional fermented milk, displayed high stability during the long-term inoculation fermentation. Our study provides valuable insights for the industrial production of traditional fermented milk.