Multiple-species biofilms as structuralized microbial communities for modulating microbiota homeostasis in human

The human body is colonized by a diverse community of microorganisms that are crucial for human health, while microbiota homeostasis is modulated by both environmental and host-derived cues. Specific microbial species form surface-attached microcolonies surrounded by their self-generated extracellular polymeric substances called biofilms. These complex assemblies may protect commensal bacteria, serving as a barrier against pathogenic microorganisms as well as hostile conditions, thus creating structuralized microbial communities for complex microbial interactions. However, biofilms formed by pathogenic bacteria will lead to invasion and perturbance of microbiota homeostasis, potentially leading to dysbiosis and diseases. In this review, we provide an in-depth analysis of the multiple-species biofilms on microbiota homeostasis within the human body. We describe the nature of biofilms in various anatomical regions, emphasizing their protective role against pathogenic invasions and their potential roles in causing disease under certain conditions. We also explore the microbial interactions between biofilms and microbial communities, emphasizing the significant potential of biofilms to alter the structure and composition of microbial assemblages. Finally, we suggest the directions for future biofilm research to enhance our understanding of the pathogenesis of diseases related to microbial dysbiosis and human health.