TY - JOUR T1 - Synthetic Photosynthetic Consortia Define Interactions Leading to Robustness and Photoproduction JF - bioRxiv DO - 10.1101/068130 SP - 068130 AU - Stephanie G. Hays AU - Leo L.W. Yan AU - Pamela A. Silver AU - Daniel C. Ducat Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/08/05/068130.abstract N2 - Microbial consortia composed of autotrophic and heterotrophic species abound in nature, yet examples of synthetic communities with mixed metabolism are limited in the laboratory. Herein, we construct artificial synthetic consortia consisting of sucrose-secreting cyanobacteria, Synechococcus elongatus PCC 7942, paired with three disparate heterotrophs: Bacillus subtilis, Escherichia coli, or Saccharomyces cerevisiae. Comparison of these different dyads highlights underlying interactions in co-culture. We witness both engineered and emergent interactions between cyanobacterium and heterotroph shared across heterotrophic species. Heterotrophs can consume carbon fixed photosynthetically by cyanobacteria while non-sucrose byproducts of photosynthesis can negatively impact heterotroph growth. Surprisingly, all tested heterotrophic species can positively impact cyanobacterial growth in co-culture in comparison to monoculture. Growth of co-cultures is witnessed in batch and continuous culture as well as on agar plates. Co-cultures persist long-term and can survive perturbation, particularly when heterotrophic sucrose uptake is enhanced and/or heterotrophic sensitivity to byproducts of photosynthetic metabolism is mitigated. This level of robustness is infrequently witnessed in synthetic microbial communities. Furthermore, by exchanging partner heterotrophs, we demonstrate flexible, phototrophic production of alpha-amylase and polyhydroxybutyrate in co-cultures containing specialized strains of B. subtilis and E. coli, respectively. Production can be improved via engineered intervention, i.e. increased efficiency growing on sucrose, showing promise for future tuning of these communities as production platforms. Altogether these synthetic microbial consortia provide a platform to study autotroph-heterotroph interactions, while demonstrating promising flexibility and stability for potential photoproduction strategies that capitalize on multi-species interactions.IMPORTANCE We describe a series of synthetic communities in which engineered cyanobacteria fix and secrete carbon to support growth of a broad range of evolutionarily-unrelated model heterotrophs. Because of the unprecedented flexibility of this consortia design, we can begin to characterize engineered and emergent interactions shared across multiple autotroph/heterotroph pairings. These observations allow us to evaluate characteristics and design principles that influence consortia robustness in a species-independent manner. For example, cyanobacterial productivity is improved by cohabitation with a broad range of heterotrophic species; an important observation for microalgal bioproduction. We show that the modular nature of our communities also allows them to be readily “reprogrammed” for photoproduction of a variety of compounds by substitution of the heterotrophic partner species. The unusual robustness and flexibility exhibited by our engineered consortia demonstrate promise as a platform that could be developed for the study of nascent symbioses, or as a highly-versatile photoproduction strategy. ER -