Microbial strategies for low-concentration substrate degradation are crucial for sustainable remediation solutions. Microorganisms in low-concentration environments use various strategies to concentrate, utilize, and metabolize substrates. These strategies include substrate-concentrating mechanisms at the cell and aggregate levels, physiological adjustments for substrate uptake, and metabolic pathways such as mixed-substrate utilization, syntrophic metabolism, dynamic responses to nutrient variation, and population density-based mechanisms. These strategies enable microorganisms to efficiently utilize low-concentration substrates and adapt to challenging oligotrophic environments. Understanding these strategies is essential for developing new approaches to tackle environmental challenges and drive the sustainability of water ecosystems, particularly in managing low-concentration contaminants like micropollutants. Aquatic ecosystems are categorized into eutrophic and oligotrophic environments based on the abundance of carbon and nutrients. Eutrophic environments have high concentrations of nutrients and labile compounds, while oligotrophic environments are resource-limited and challenge microorganisms to adapt to low concentrations of poorly degradable nutrients and organic carbon. Microorganisms in oligotrophic environments must employ specialized metabolic strategies to effectively compete for limited resources, including producing extracellular enzymes and scavenging to utilize scarce substrates. Understanding microbial adaptation in oligotrophic environments is critical for managing emerging environmental concerns. Emerging organic carbon, including micropollutants, poses significant ecological and health risks due to their low concentrations and toxic effects. Recent regulatory efforts, such as the European Commission's proposals for stricter standards for controlling emerging pollutants, highlight the urgency of understanding microbial interactions with low-concentration contaminants. These efforts aim to improve urban wastewater treatment and protect public health and the environment. Microbial strategies for low-concentration substrate utilization include substrate concentrating mechanisms, such as carbon, nitrogen, and sulfate concentrating mechanisms, and biofilm formation. These strategies allow microorganisms to survive in nutrient-scarce environments by concentrating substrates, forming structured communities, and sharing resources. Microbial transport mechanisms and substrate affinity also play crucial roles in nutrient uptake and utilization under low-concentration conditions. Microbial metabolic pathways, including mixed-substrate utilization and syntrophic metabolism, enable microorganisms to efficiently utilize low-concentration substrates and adapt to changing environmental conditions. These pathways are essential for maintaining ecological balance and supporting sustainable environmental management. Understanding these strategies is vital for developing effective bioremediation techniques and promoting the sustainability of aquatic ecosystems.Microbial strategies for low-concentration substrate degradation are crucial for sustainable remediation solutions. Microorganisms in low-concentration environments use various strategies to concentrate, utilize, and metabolize substrates. These strategies include substrate-concentrating mechanisms at the cell and aggregate levels, physiological adjustments for substrate uptake, and metabolic pathways such as mixed-substrate utilization, syntrophic metabolism, dynamic responses to nutrient variation, and population density-based mechanisms. These strategies enable microorganisms to efficiently utilize low-concentration substrates and adapt to challenging oligotrophic environments. Understanding these strategies is essential for developing new approaches to tackle environmental challenges and drive the sustainability of water ecosystems, particularly in managing low-concentration contaminants like micropollutants. Aquatic ecosystems are categorized into eutrophic and oligotrophic environments based on the abundance of carbon and nutrients. Eutrophic environments have high concentrations of nutrients and labile compounds, while oligotrophic environments are resource-limited and challenge microorganisms to adapt to low concentrations of poorly degradable nutrients and organic carbon. Microorganisms in oligotrophic environments must employ specialized metabolic strategies to effectively compete for limited resources, including producing extracellular enzymes and scavenging to utilize scarce substrates. Understanding microbial adaptation in oligotrophic environments is critical for managing emerging environmental concerns. Emerging organic carbon, including micropollutants, poses significant ecological and health risks due to their low concentrations and toxic effects. Recent regulatory efforts, such as the European Commission's proposals for stricter standards for controlling emerging pollutants, highlight the urgency of understanding microbial interactions with low-concentration contaminants. These efforts aim to improve urban wastewater treatment and protect public health and the environment. Microbial strategies for low-concentration substrate utilization include substrate concentrating mechanisms, such as carbon, nitrogen, and sulfate concentrating mechanisms, and biofilm formation. These strategies allow microorganisms to survive in nutrient-scarce environments by concentrating substrates, forming structured communities, and sharing resources. Microbial transport mechanisms and substrate affinity also play crucial roles in nutrient uptake and utilization under low-concentration conditions. Microbial metabolic pathways, including mixed-substrate utilization and syntrophic metabolism, enable microorganisms to efficiently utilize low-concentration substrates and adapt to changing environmental conditions. These pathways are essential for maintaining ecological balance and supporting sustainable environmental management. Understanding these strategies is vital for developing effective bioremediation techniques and promoting the sustainability of aquatic ecosystems.