DEVELOPMENT OF GENETIC TOOLKIT AND SYNTHETIC CIRCUITRY IN CHROMOBACTERIUM VIOLACEUM FOR GOLD BIOLEACHING

Abstract

An attractive microbial cell factory application is in the gold recycling of electronic waste that uses the highly toxic cyanide for gold leaching. The cyanogenic bacterium, Chromobacterium violaceum, is one of the highest producers of cyanide and one of the most efficient at solubilizing gold from electronic waste. However, studies are limited to wild type bacterium, limiting the potential of the microbial cell factory. In this thesis, a genetic toolkit consisting of origin of replications, antibiotic resistance cassettes and promoters are first developed in this non-model bacterium. CRISPRi is also shown successfully in C. violaceum for knockdown of endogenous gene expression. Subsequently, a synthetic circuitry for autonomous gold bioleaching is designed to enable ON-OFF dynamic regulation of cyanide production in the face of toxic gold ions. This study provides a platform for future design-build-test cycles of developing C. violaceum into an autonomous gold bioleaching microbial cell factory with synthetic biology.