State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, People's Republic of China.
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China.
Microbiome. 2021 Sep 1;9(1):180. doi: 10.1186/s40168-021-01108-8.
Probiotics have been used to regulate the gut microbiota and physiology in various contexts, but their precise mechanisms of action remain unclear.
By population genomic analysis of 418 Bifidobacterium longum strains, including 143 newly sequenced in this study, three geographically distinct gene pools/populations, BLAsia1, BLAsia2, and BLothers, were identified. Genes involved in cell wall biosynthesis, particularly peptidoglycan biosynthesis, varied considerably among the core genomes of the different populations, but accessory genes that contributed to the carbohydrate metabolism were significantly distinct. Although active transmission was observed inter-host, inter-country, inter-city, intra-community, and intra-family, a single B. longum clone seemed to reside within each individual. A significant negative association was observed between host age and relative abundance of B. longum, while there was a strong positive association between host age and strain genotype [e.g., single nucleotide polymorphisms in the arginine biosynthesis pathway]. Further animal experiments performed with the B. longum isolates via using a D-galactose-induced aging mouse model supported these associations, in which B. longum strains with different genotypes in arginine biosynthesis pathway showed divergent abilities on protecting against host aging possibly via their different abilities to modify the metabolism of gut microbes.
This is the first known example of research on the evolutionary history and transmission of this probiotic species. Our results propose a new mechanistic insight for promoting host longevity via the informed use of specific probiotics or molecules. Video abstract.
益生菌已被用于调节各种情况下的肠道微生物群和生理学，但它们的确切作用机制仍不清楚。
通过对包括本研究中新测序的 143 株在内的 418 株长双歧杆菌菌株的群体基因组分析，鉴定出三个具有地理差异的基因库/种群，即 BLAsia1、BLAsia2 和 BLothers。不同种群核心基因组中的细胞壁生物合成相关基因，特别是肽聚糖生物合成相关基因，差异很大，但对碳水化合物代谢有贡献的辅助基因则有明显的不同。尽管在宿主间、国家间、城市间、社区内和家庭内都观察到了活跃的传播，但每个个体似乎只存在一个长双歧杆菌克隆。宿主年龄与长双歧杆菌相对丰度之间存在显著负相关，而宿主年龄与菌株基因型（如精氨酸生物合成途径中的单核苷酸多态性）之间存在很强的正相关。通过使用 D-半乳糖诱导的衰老小鼠模型对长双歧杆菌分离株进行的进一步动物实验支持了这些关联，其中精氨酸生物合成途径中具有不同基因型的长双歧杆菌菌株在保护宿主衰老方面表现出不同的能力，这可能是通过其改变肠道微生物代谢的不同能力实现的。
这是首次对该益生菌种的进化历史和传播进行研究。我们的研究结果为通过使用特定益生菌或分子来促进宿主长寿提供了新的机制见解。视频摘要。
