Engineering and understanding self-sustaining, structured phototrophic microbial communities in hydrogels and biofilms for biocatalytic applications

• Applicants: Dr.-Ing. Rohan Karande; Professor Dr. Tilo Pompe
• Subject Area: Biological Process Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 464311431

Phototrophic microbial mats are a very remarkable biological (eco)-system evolved in nature for effective energy and material flow with vertically structured microbial communities. These mats are robust and stable under extreme environmental conditions and can efficiently utilize the solar spectrum based on the concerted activity of different microorganisms. These emergent properties of spatially organized phototrophic microbial communities are highly attractive from biotechnological aspects to design energy-efficient photo-biocatalytic processes. However, understanding the functions and interactions of microbial species in such structured microbial communities and the engineering of connected biotechnological processes is experimentally challenging and virtually non-existent.This project aims to have a quantitative understanding of the fundamental parameters needed to engineer structured phototrophic microbial communities in biofilms. To achieve this, we will join our expertise in (bio)materials engineering and microbial biotechnology. We will use phototrophic and heterotrophic microorganisms' concerted activity to design vertically structured microbial communities that allow maximum conversion of light energy into bio-hydrogen (H2) production. The model strains Synechocystis sp. PCC 6803 M55, Anabaena sp. PCC 7120 AMC 414, Rhodopseudomonas palustris, and Pseudomonas sp. VLB120 are selected as relevant trophies to access the maximal amount of solar light conversion and to stabilize chemical redox equilibrium. We propose two experimental platforms (hydrogels and biofilms) with integrated analytics to explore structure, stability, and metabolic performance of the phototrophic microbial community. The quantitative analysis of light conversion and mass balances correlated to the structure of microbial communities in hydrogels will be translated to set operational conditions necessary to establish vertically structured biofilms. The system's biotechnological performance will be evaluated in terms of H2 production efficiency.To achieve our goal, the work program will include the following steps: (1) engineering a materials-based cultivation toolbox to manipulate and analyze multispecies phototrophic microbial communities in immobilized formats for control of structure as well as mass and light fluxes, (2) quantitative analysis of naturally evolving mixed-species phototrophic biofilms in flow-cell setups with access to structural evolution as well as light and mass fluxes, and (3) exploration of the operational window of structured microbial communities for efficient light conversion in bio-H2 production.In perspective, we aim to provide new options for using structured phototrophic microbial communities in biofilms in various biotechnological applications for efficient light conversion and advanced product synthesis.

• DFG Programme: Research Grants