Signal-guided microbial communities enhance the entrapment of rare earth elements

Area of Science:

• Microbiology
• Environmental Science
• Biotechnology

Background:

• Microbial communities form aggregates, influencing ecosystem functions.
• Quorum sensing (QS) regulates microbial interactions but its role in aggregate-based rare earth element (REE) entrapment is unclear.
• Microbial aggregates are complex, hindering understanding of their ecological roles, especially in REE sequestration from waste.

Purpose of the Study:

• To investigate how QS, specifically acyl-homoserine-lactones (AHLs), influences REE entrapment in periphytic biofilms (PBs).
• To assess the efficiency of AHL-enhanced PBs for REE recovery from diverse waste streams.
• To elucidate the mechanisms by which AHLs facilitate REE entrapment and mitigate stress in microbial aggregates.

Main Methods:

• Utilized periphytic biofilm (PB) as a model microbial aggregate.
• Applied acyl-homoserine-lactones (AHLs) to enhance QS in PBs.
• Quantified REE entrapment capacity and efficiency in native and AHL-enhanced PBs.
• Analyzed the impact of AHLs on biopolymer synthesis, community structure, and stress tolerance.

Main Results:

• AHL-enhanced PBs showed approximately a 2x increase in REE entrapment capacity compared to native PBs.
• Achieved high REE entrapment efficiencies (up to ~96%) in simulated and real-world waste streams (mine wastewater, e-waste, coal fly ash).
• AHLs promoted biopolymer production, aiding REE sequestration via electrostatic interactions, proton release, and precipitation, while enhancing community resilience to pH and REE stress.

Conclusions:

• QS via AHLs significantly enhances REE entrapment in microbial aggregates.
• This strategy offers a viable, green approach for REE recovery from industrial waste, supporting a circular economy.
• AHL-mediated biopolymer production and community protection mechanisms are key to efficient and stable REE sequestration.