Cyanobacteria offer advantages to microbial fuel and chemical production, including use of non-arable land, high-efficiency photon harvesting, and direct production. However, synthetic pathway construction in photosynthetic hosts is still nascent compared to model fermentative organisms. In this study, we installed a new metabolic pathway in the cyanobacterium Synechococcus elongatus PCC7942 and used this as a model system to establish design methods for efficient exogenous chemical production. To adapt the pathway to photosynthetic cells, we matched reducing cofactors to the host, avoided oxygen sensitive enzymes, and optimized gene codons. We applied irreversible enzymatic steps to create a driving force toward the target molecule and identified low product toxicity enabling high titers. Through a screening process, we achieved a pathway where endogenous synthesis of precursors became the apparent limiting step. We observed an increase in oxygen evolution, correlating to high carbon redirection away from metabolism, which indicates possibilities for increasing photosynthetic efficiency.

Metabolic design for cyanobacterial chemical production

245th National Meeting (2013)

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