Use of phototrophic biofilms in the agricultural sector to improve plant growth

• Applicant: Dr.-Ing. Dorina Strieth
• Subject Area: Biological Process Engineering ; Plant Cultivation, Plant Nutrition, Agricultural Technology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 464589509

In 2018, around 866 million tons of greenhouse gases were produced in Germany, with agriculture accounting for 10-12 % of anthropogenic greenhouse emissions worldwide. While the exchange of CO2 is almost balanced by the simultaneous fixation of CO2 in organic mass, agriculture accounts for 50 % of all emissions of methane and nitrous oxide even 60 % of all emissions. This is mainly due to the use of mineral and organic fertilizers. Without active countermeasures, nitrous oxide emissions in agriculture are expected to increase by 30- 65 % by 2030. In order to achieve the climate-political goal of reaching greenhouse gas neutrality by 2050, a climate-friendly cultivation of renewable raw materials in agriculture is an important strategy. A central aspect of this strategy could be the establishment of terrestrial cyanobacteria, which are tolerant to biotic and abiotic conditions. Additionally, they are able to fix atmospheric nitrogen and convert it into bioavailable nitrogen that can be used by other organisms and released into the environment. In addition, terrestrial cyanobacteria grow embedded in a matrix of extracellular polymeric substances, which could contribute to a desirable soil stabilization and thus to the protection against soil erosion and to the promotion of water storage in the soil. For this purpose, nitrogen-fixing cyanobacteria isolated from the cool temperate climate zone will be used. Suitable strains must have spatially separated the nitrogen fixation from the process of photosynthesis by the formation of heterocysts and release the bioavailable nitrogen into the environment. Co-cultures of cyanobacteria with Arabidopsis thaliana (thale cress) and Triticum aestivum (wheat) should show whether an artificially induced symbiosis is possible. Besides the agricultural plant wheat, A. thaliana was selected because it is a fast-growing and well characterized model plant. Furthermore, it belongs to the same family as the crops cabbage, broccoli and horseradish. For the application of the biofilms in agriculture, they will be immobilized on a biodegradable carrier material. For this purpose, an aerosol-based photobioreactor will be designed and characterized and an inoculation and harvesting procedure will be established. Additionally, the water retention of the biofilms will be optimized by varying the process parameters. Finally, the co-cultivation of immobilized cyanobacteria on carrier material and plants in plant substrates as a function of temperature will be investigated. Here the question shall be answered whether a periodic application of the cyanobacteria is necessary or whether a permanent implementation of biofilms in the soil is possible.

• DFG Programme: Research Grants