Current knowledge on cyanobacterial biobutanol production: advances, challenges, and prospects

The development of alternative, sustainable sources of fuels is necessary for addressing the increasing world’s energy demand and global warming crisis. Butanol, an important and promising biofuel candidate, is generally produced from heterotrophic microorganisms by carbohydrate fermentation. Cyanobacteria can serve as an alternative feedstock for third and fourth-generation biofuel production. Biofuel and biochemical synthesis from CO₂ using photosynthetic organisms is an attractive approach. These prokaryotic photosynthetic microorganisms have been used as an energy feedstock and also genetically engineered for direct conversion of CO₂ into butanol. This review aims to highlight the crucial aspects of photosynthetic biobutanol synthesis. The review explores the recent advances in biobutanol production from cyanobacteria. It reviews the recent and classical cyanobacterial genetic modification approaches and the advances in synthetic biology toolboxes of cyanobacteria. It discusses both third and fourth-generation butanol synthesis while emphasizes more on genetic modifications used in metabolic engineering and their effects on butanol production. Challenges associated with strain development, cultivation, butanol toxicity, and recovery have also been discussed.