The response of biofilms to nutrient environments and their potential in biogeochemical cycles

Biofilms play a central role in mediating biogeochemical cycling across diverse natural and engineered ecosystems. Research on biofilms continues to expand, but a comprehensive understanding of their adaptive responses to nutrient fluctuations remains lacking. Environmental nutrients act as signals that trigger multiple mechanisms controlling extracellular polymeric substance production and microbial selection. Nutrient availability and stoichiometry are sensed through interconnected regulatory networks involving two-component systems, second messengers, and transcriptional regulators, which collectively direct biofilm formation, matrix investment, and dispersal. Under nutrient heterogeneity, biofilms also exhibit spatial self-organization and coordinated collective behaviors that enhance resource partitioning and functional differentiation. Biofilms function as biogeochemical hotspots that support diverse microbial communities, including nitrogen-fixing and denitrifying bacteria. These properties make them important for wastewater treatment in engineered systems. In addition, the plastisphere acts as a distinct biofilm ecosystem, creating new ecological and biogeochemical relationships. This review integrates nutrient-driven regulations from intracellular signaling to community-scale self-organization and links these mechanisms to biogeochemical functions, providing an integrative conceptual framework for predicting and comparing biofilm responses across scales. Together, these insights provide a conceptual basis for improving the design and management of biofilms in bioremediation, nutrient recovery, and low-carbon wastewater treatment, while also highlighting the context dependence and current limitations of predictive control.