Optogenetic Control of Microbial Consortia for the Optimization of Chemical Production

Abstract

Metabolic engineering involves modifying genetic pathways in microbes to more sustainably and efficiently produce countless chemical compounds. However, engineered metabolic pathways induce metabolic burden within microbial strains, which can inhibit microbial growth and product formation. Microbial consortia divide metabolic labor among two or more microbial strains but require concurrent systems of control to ensure that one strain does not out-compete another and that microbes in consortia are operating at optimum ratios to maximize product formation. This research builds on previous work, which used optogenetic control to dynamically control microbial growth using blue light-activated genetic circuits. In this research, we study consortia of Saccharomyces cerevisiae and optogenetically controlled Escherichia coli to produce isobutyl acetate, a compound valuable in the food and fragrance sectors, as well as naringenin, a valuable pharmaceutical compound. Fermentations reveal that intermediate light duties produce the highest final product titers. We then explore the use of media containing lignin-derived organic acids with S. cerevisiae engineered to produce naringenin. Lignin is a complex byproduct of many chemical processes whose valorization has important economic and environmental implications. We characterize the toxicity of many of these acids to S. cerevisiae before examining the potential detoxifying effects of optogenetically controlled Pseudomonas putida in consortia with S. cerevisiae. Previous research has demonstrated the potential for P. putida to break down organic acids present in pretreated lignin streams. This research demonstrates how optogenetic. control can optimize the renewable and efficient production of several natural compounds in microbial consortia. Future work can draw upon this research to more sustainably and efficiently produce several valuable chemical compounds with applications in lignin valorization.