One of the major challenges of todays´ society is the shift of the chemical industry from being based on fossil feedstocks and relying on unsustainable processes towards renewable resources and eco-friendly manufacturing processes. The Cell4Chem project fits into these endeavours by harnessing the power of microbial communities. Microorganisms are poster children of circular processes, having kick-started the first global elemental cycles and having sustained them ever since. Today, microbial communities are routinely used in biotechnological processes such as wastewater treatment and biogas production, however, the ability to control these systems has been limited.
Cell4Chem aims at providing tools and strategies to unlock the full potential of microbial communities and enabling transformation processes that end in high-value products from sustainable feedstocks. Medium-chain carboxylates (MCC) such as caproate and caprylate are specialty chemicals with broad application spectra. Up to now, the use of sustainable feedstocks such as agro-industrial waste and residues for MCC production is mostly limited to biomass with high ethanol or lactate content, as such electron donors are crucial for reaching efficient MCC production processes. The exploitation of more abundant lignocellulosic biomass has the potential of greatly expanding the application of this new anaerobic fermentation technology, however, it harbours two major bottlenecks, i.e. the poor hydrolysis of cellulose and low internal production of lactate.
Overview of the work packages in Cell4Chem project
Cell4Chem tackles these issues on three engineering levels. On the first level, different bacterial strains including lactic acid bacteria will be genetically modified to create metabolic specialists for cellulose hydrolysis and lactate production in a Synthetic Biology approach. On the second level, these specialised bacterial strains will be combined in de novo constructed consortia with various wildtype microorganisms or enriched consortia including chain-elongating bacteria that can convert lactate into MCC. On the third engineering level, anaerobic bioreactors will be operated with microbiota with the aim to develop process strategies for targeted steering of anaerobic fermentation towards MCC formation. Experiences from these reactor experiments will be exploited for tailored upscaling of the most promising designed consortia. The communities will be monitored over time using nextgeneration amplicon sequencing and metaomics methods such as metagenomics and metaproteomics in order to follow community dynamics and process performance, leading to time series data and the recovery of genomes of not yet described species. This information will be further processed by bioinformatics tools to construct species-specific metabolic models that are combined to quantitative, mechanistic microbial community models, which both are parameterised towards the experimental data in order to elucidate determinants of observed dynamics, and to screen for optimal community compositions (Systems Biology).
Producing MCC from cellulose-based feedstocks (instead of e.g. palm oil) will demonstrate the validity of the methods used in Cell4Chem to modify microbial consortia in a controlled manner. Beyond this proof-of-concept, the project shows the potential of microbial communities to convert renewable feedstocks into desirable feedstocks in a sustainable way.
