Optogenetic Control of Microbial Growth for Consortia Population Optimization

Abstract

The metabolic pathways of microorganisms can be engineered for efficient production of valuable chemicals such as fuels, fragrances and medicines. However, having a single organism harbor a complex metabolic pathway may lead to a metabolic burden on that organism, and ultimately lead to inefficient chemical production. Co-culturing multiple organisms and dividing the metabolic pathway between them allows for efficiency in product synthesis, but also requires control over population size. The optimization of the relative population sizes of different organisms in a consortium is an area of active research. Here, we show that the population ratio of an Escherichia coli and Saccharomyces cerevisiae consortium can be controlled by engineering their growth to be light-dependent. Using a blue/dark optogenetic system, we engineer a strain of E. coli that grows under blue light and use it in tandem with an engineered S. cerevisiae strain that grows in the dark; when grown together under different light conditions, a variety of bacteria to yeast ratios are achieved. The results show the first application of optogenetics for consortia population control. In the future, we can apply this technology for efficient chemical production.