Microbial fixation of CO2 in water bodies and in drylands to combat climate change, soil loss and desertification

The growing concern for the increase of the global warming effects due to anthropogenic activities raises the challenge of finding novel technological approaches to stabilize CO2 emissions in the atmosphere and counteract impinging interconnected issues such as desertification and loss of biodiversity.Biological-CO2 mitigation, triggered through biological fixation, is considered a promising and eco-sustainable method, mostly owing to its downstream benefits that can be exploited. Microorganisms such as cyanobacteria, green algae and some autotrophic bacteria could potentially fix CO2 more efficiently than higher plants, due to their faster growth. However, multiple factors have to be optimized for maximum rate of CO2 fixation by these microorganisms. The design of photobioreactors, the optimization of culture conditions including the optimal concentration of CO2 in the provided gas, the use of metabolic engineering and the use of dual purpose systems for the treatment of wastewater and production of biofuels and high value products within a biorefinery, among others, have to be developed and tested for cost-effective CO2 sequestration. In arid and semiarid environments, soil carbon sequestration (CO2 fixation) by cyanobacteria and Biological Soil Crusts represent an eco-friendly and natural process to increase soil C content, and a viable pathway to soil restoration after one disturbance event. Within this context, inoculation-based techniques have proved to be a viable and sustainable pathway to increase soil biomass, soil stabilization and to increase soil fertility.