Metabolic and genetic engineering of cyanobacteria for enhanced hydrogen production

There is an urgent need to develop sustainable solutions to convert solar energy into energy carriers used in society. In addition to solar cells generating electricity, there are several options to generate solar fuels, with molecular hydrogen being an interesting and promising option. Native and engineered cyanobacteria have been used as model systems to examine, develop and demonstrate photobiological hydrogen production. In the present review we present and discuss recent progress with respect to native biological systems to generate hydrogen, metabolic modulations, and genetic engineering of metabolic pathways, as well as the introduction of custom-designed, non-native enzymes and complexes for enhanced hydrogen production in cyanobacteria. In conclusion, metabolic and genetic engineering of native cyanobacterial hydrogen metabolism can significantly increase the hydrogen production. Introduction of custom-designed non-native capacities open up new possibilities to further enhance cyanobacterial-based hydrogen production.