Cyanobacteria and Friends: Engineered Photosynthetic Microbial Communities

Abstract

Microbial communities are the rule rather than the exception. Laboratories using model organisms often focus on monoclonal, axenic cultures overlooking the importance of the interactions, division of labor, and robustness of consortia. This thesis presents the construction, characterization, and exploration of multiple engineered photosynthetic communities. Division of labor is inherent in the use a phototroph (the model cyanobacterium Synechococcus elongatus) to capture solar energy and fix carbon for the community, paired with various heterotrophs (Escherichia coli, Bacillus subtilis, and Saccharomyces cerevisiae) that cannot grow without the phototroph. Within these microbial communities, engineered interactions (i.e., feeding of fixed carbon from cyanobacteria to heterotrophs) are observed along with un-engineered interactions. The unexpected, emergent interactions include increased phototroph growth in consortia in comparison to monoculture and inhibition of heterotroph growth with phototrophs in a density and light dependent manner. Using these communities, we show robustness to culture perturbations through time as well as flexible functionalization to make target compounds. We are continuing this work to unearth the mechanisms underlying these interactions using community-scale models across these and other synthetic photosynthetic consortia. Finally, we made use of microbial consortia in various outreach exhibits to spark public interest in science, biotechnology, and microbial communities.