To convert optical energy into electric energy in a clean and sustainable way, Optopia is designed as a photovoltaic system consisting of two subsystems: photosynthetic microorganism system (Synechocystis sp. or Rhodopseudomonas palustris) and electrogenic microorganism system (Shewanella oneidensis). Synthetic biology strategies are applied to the system to trigger production and export of lactate in photosynthetic microorganisms, as well as to improve efficiency of lactate utilization and extracellular electron generation in electrogenic microorganism system.
Synechocystis, one kind of cyanobacteria, is more mature than Rhodopseudomonas in lactate production, but generating lots of oxygen during photosynthesis. Given the fact that Shewanella favors anaerobic environment for electricity production, Rhodopseudomonas may serve as a better carbon resource provider for Shewanella, not only because of its anaerobic photosynthesis maintaining an anaerobic environment required for extracellular electron generation in Shewanella, but also due to its capacity of reusing the waste from Shewanella. Hence, we construct a Synechocystis- Shewanella MFC and a Rhodopseudomonas - Shewanella MFC to find an optimized version of Optopia, maximzing the conversion of optical energy to electric energy.