Challenges and opportunities in C1-based biomanufacturing

[Display omitted] •C1 biorefinery provides a solution to energy crisis and greenhouse effect.•Main C1 compounds are reviewed as abundant and cheap feedstocks in C1 biorefinery.•Various C1 fixation pathways are analyzed for their roles in carbon assimilation.•Natural &non-natural C1 using microbes are discussed as hosts for C1 biorefinery. The intensifying impact of green-house gas (GHG) emission on environment and climate change has attracted increasing attention, and biorefinery represents one of the most effective routes for reducing GHG emissions from human activities. However, this requires a shift for microbial fermentation from the current use of sugars to the use of biomass, and even better to the primary fixation of single carbon (C1) compounds. Here how microorganisms can be engineered for fixation and conversion of C1 compounds into metabolites that can serve as fuels and platform chemicals are reviewed. Meanwhile, key factors for utilization of these different pathways are discussed, followed by challenges and barriers for the development of C1-based biorefinery.