Engineering Bioactive Materials for Pollutant Removal and Microbial Control in Water Reclamation

Water scarcity and pollution are critical environmental issues worldwide. Particularly, urban water system, providing safe drinking water and wastewater treatment for public health, have been challenged by aging infrastructure, population growth, and climate change. One emerging solution to enhance urban water security involves decentralized treatment and reuse of municipal wastewater and stormwater to supplement the conventional water supply. Coupled with the drive to minimize the energy and environmental footprints of cities, there is an urgent need to develop efficient and environmental benign technology for decentralized water treatment and reclamation. In this thesis, the overarching goal is to harnesses the power of synthetic biology techniques and microbial cell machinery to design protein/peptide based bioactive materials to remove pollutants of emerging concern, and sense and kill bacteria pathogens for enhanced wastewater treatment and reclamation.

Emerging contaminants such as pharmaceuticals and personal care products are biologically active and potentially harmful to human health and ecosystems, and they tend to be persistent or only partially removed by conventional wastewater treatment processes. Therefore, we created a surface display laccase (SDL) and characterized its biocatalytic properties in removing an emerging contaminant. Meanwhile, water contamination by pathogenic bacteria is still a major public health concern, thus we engineered a novel whole-cell biosensor to detect two critical causative agents for waterborne diseases, Pseudomonas aeruginosa and Burkholderia pseudomallei. The biosensor detected the target bacterial pathogens with high sensitivity by responding to quorum sensing signal molecules of bacterial pathogens. We also developed a new type of antimicrobial agent for bacteria disinfection by immobilizing an antimicrobial peptide on the surface of engineered biobeads. This new antimicrobial agent had antimicrobial activity against Escherichia coli and Bacillus subtilis with reduction efficiency up to 6 log and 4 log respectively.

This research provides scientific basis for developing and implementing surface display laccase as an innovative biocatalytic material for contaminant treatment applications, and a proof-of-concept study of designing a whole-cell biosensor and antimicrobial biobeads for microbial control in water reclamation. The result of our study demonstrated the effectiveness and potential of engineered cell systems in advancing water treatment towards environmental sustainability.