In nature, cells compartmentalize their internal spaces by creating physical barriers to centralize specific biochemical reactions and store useful compounds. The proteinaceous compartments are able to encapsulate enzyme cargos and act as catalytic machineries in various biological processes, such as carbon fixation and nutrient metabolism. We are interested in designing and building these protein assemblies (such as vault) for addressing global environmental needs in remediation, monitoring, and sustainable energy. Co-localizing key pathway enzymes in confined spaces in cells can greatly stimulate intermediates transfer between enzymes and prevent side reactions, and therefore enhance overall biotransformation rates. Our goal is to construct in vivo catalytic nanocompartments for bioremediation, bioenergy production, and resource recovery, and in vitro bionanoreactors for water treatment and water quality monitoring.