Deciphering and engineering high-light tolerant cyanobacteria for efficient photosynthetic cell factories

Development and utilization of ‘‘liquid sunshine" could be one of key solutions to deal with the issues of fossil fuel depletion and increasing carbon dioxide.Cyanobacteria are the only prokaryotes capable of performing oxygenic photosynthesis, and their activity accounts for ～25% of the total carbon fixation on earth.More importantly, besides their traditional roles as primary producers, cyanobacteria could be modified as ‘‘photosynthetic cell factories" to produce renewable fuels and chemicals directly from CO2driven by solar energy, with the aid of cutting-edging synthetic biology technology.Towards their large-scale biotechnological application in the future, many challenges still need to be properly addressed, among which is cyanobacterial cell factories inevitably suffer from high light(HL) stress during large-scale outdoor cultivation, resulting in photodamage and even cell death, limiting their productivity.In this review, we critically summarized recent progress on deciphering molecular mechanisms to HL and developing HL-tolerant chassis in cyanobacteria, aiming at facilitating construction of HLresistant chassis and promote the future application of the large-scale outdoor cultivation of cyanobacterial cell factories.Finally, the future directions on cyanobacterial chassis engineering were discussed.