Influence of spatial structure on the assembly and interactions of microbial communities in fermented foods: Current status and future perspectives.

The quality and stability of fermented foods largely depend on the cooperative metabolism of microbial communities. These microorganisms are not randomly distributed but colonize fermentation substrates with complex spatial structures. An increasing number of studies show that spatial structure not only influences spatial adjacency and mass exchange pathways among microorganisms, but also influences community succession and functional outputs by shaping microenvironments. This review focuses on the mechanisms by which spatial structure reshapes microbial interactions, with particular emphasis on its regulatory effects on microbial community assembly and interactions. Evidence indicates that spatial segregation promotes coexistence by reducing competitive exclusion among competing populations, whereas moderate spatial heterogeneity increases community diversity and stability by increasing the number of ecological niches. This spatial structure-mediated assembly mechanism shapes microbial interaction networks and thereby affects the quality and stability of fermented foods. At present, this field remains limited by a lack of direct causal evidence linking spatial structure, local interactions, and functional outputs, and by restricted cross-scale predictive capabilities. This review aims to systematically elucidate the ecological functions of spatial structure in fermented foods and to provide a theoretical basis and research perspective for improving the quality of fermented foods through the regulation of spatial structure.