Light-driven synthetic microbial consortia: playing with an oxygen dilemma.

Background: Light-driven synthetic microbial consortia are composed of photoautotrophs and heterotrophs. They exhibited better performance in stability, robustness and capacity for handling complex tasks when comparing with axenic cultures. Different from general microbial consortia, the intrinsic property of photosynthetic oxygen evolution in light-driven synthetic microbial consortia is an important factor affecting the functions of the consortia. Results: In light-driven microbial consortia, the oxygen liberated by photoautotrophs will result in an aerobic environment, which exerts dual effects on different species and processes. On one hand, oxygen is favorable to the synthetic microbial consortia when they are used for wastewater treatment and aerobic chemical production, in which biomass accumulation and oxidized product formation will benefit from the high energy yield of aerobic respiration. On the other hand, the oxygen is harmful to the synthetic microbial consortia when they were used for anaerobic processes including biohydrogen production and bioelectricity generation, in which the presence of oxygen will deactivate some biological components and compete for electrons. Conclusions: Developing anaerobic processes in using light-driven synthetic microbial consortia represents a cost-effective alternative for production of chemicals from carbon dioxide and light. Thus, exploring a versatile approach addressing the oxygen dilemma is essential to enable light-driven synthetic microbial consortia to get closer to practical applications.