Comparative Genomics and Adaptive Evolution of Bifidobacterium adolescentis in Geographically Distinct Human Gut Populations

Abstract

Bifidobacterium adolescentis is prevalent in the gastrointestinal tract of healthy humans, and significantly influences host health. Recent studies have predominantly investigated the probiotic characteristics of individual strains and their specific metabolic roles, whereas analyses at the population genome level have been limited to date. This study conducted a comparative genomics analysis of 543 B. adolescentis genomes to explore genetic background variations and functional gene differences across geographically diverse populations. The results revealed significant differences in genome size and GC content among populations from Asia, Europe, and North America (p < 0.05). The pan-gene exhibited an open structure, reflecting the substantial genetic diversity within B. adolescentis. Functional annotation demonstrated that B. adolescentis possesses numerous protein-coding genes and abundant carbohydrate-active enzymes (CAZys) implicated in carbohydrate degradation and transformation. Population-specific CAZys were identified, suggesting adaptive evolution driven by distinct regional dietary patterns.