Factors influencing gut microbial colonization: A host-microbe-environment interaction perspective

Gut microbial colonization is a dynamic balance shaped by host genetics and immunity, microbial ecology, and environmental exposures. This review synthesizes evidence on host barriers and immunity-mucus architecture, antimicrobial peptides, pattern recognition receptors, and secretory IgA-and on genetic loci such as LCT and ABO/FUT2 that modulate nutrient landscapes and strain selection. Microbial adaptability is summarized, including polysaccharide utilization loci and human milk oligosaccharide metabolism, bile salt hydrolase-mediated tolerance, extracellular polysaccharide-driven immune modulation, oxygen-gradient-linked metabolic partitioning, and adhesion mechanisms that secure niche occupancy. Environmental perturbations are evaluated, spanning dietary patterns, protein sources, polyphenols, food additives, pharmaceuticals, and lifestyle factors such as physical activity, circadian alignment, and smoking, which reshape resource competition, barrier integrity, and community resilience. Interaction frameworks that govern stability and dysbiosis are delineated, including competitive inhibition, cross-feeding, quorum sensing, cross-kingdom crosstalk among bacteria, fungi, and phages, and horizontal gene transfer that accelerates adaptation and resistance. Niche elasticity is proposed as a systems metric to quantify stability and recovery after perturbation. Translational strategies combine engineered probiotics, anti-adhesion approaches, and rationally designed phages and lysins with in situ multi-omics to enable mechanism-guided, personalized interventions for food science and microbial engineering.