Climate-friendly production of renewable resources by the innovative use of diazotrophic, terrestrial cyanobacteria

Renewable raw materials from agriculture help to reduce greenhouse gases, as they expand the CO₂ cycle and release less greenhouse gases than fossil raw materials when used for energy purposes. However, since high levels of nitrous oxide are released, especially by organic fertilization, no emission-free production of renewable raw materials is possible so far. Accordingly, there is an urgent need to replace organic and mineral fertilizers with nitrogen-binding systems. Here, diazotrophic (atmospheric nitrogen fixing), terrestrial cyanobacteria provide a way to fix atmospheric nitrogen and pass it on to plants for the production of renewable raw materials. Especially terrestrial cyanobacteria grow embedded in a thick matrix of extracellular polymeric substances which can contribute to a desirable soil stabilization and thus protection against soil erosion and to promoting water retention in the soil.

The main goal of this research is the sustainable establishment of nitrogen-fixing terrestrial cyanobacteria, which are immobilized on biodegradable carriers, in the ground in agriculture. Based on the aerosol-based photobioreactors constructed and established at the chair of bioprocess engineering, a new reactor system for the cultivation of cyanobacteria on carriers was developed and characterized. In addition, a screening for potential diazotrophic terrestrial cyanobacteria including the formation from vegetative cells to heterocysts (nitrogen fixing cells), nitrogen uptake and release rates for the use in the German agricultural economy was performed. A proof-of-principle to prove the use of terrestrial cyanobacteria as fertilizer for a climate-friendly production of renewable resources was tested by sowing seeds of Arabidopsis thaliana on agar plates with and without nitrogen as well as with and without a diazotrophic phototrophic biofilm.

This project is financially supported by the def DFG (UL 170/16-1) and the “Landesforschungsschwerpunkt NanoKat”.