ERA-NET: Bioprocesses for the optimized, integrated production of butyl esters from sustainable resources

The ERA-CoBioTech project BESTER aimed to establish clostridial bioprocesses for an optimized integrated production of a range of different butyl esters for the commodity chemicals market. Efficient organic acid production using lignocellulosic sugars as a sustainable feedstock should be developed, linkable to ABE fermentation processes on similar feedstock as a source of BuOH. BESTER thereby addressed in a coordinated way the two key handles for efficient production of three different organics acids, i.e. a) Systems biology guided strain engineering using Synthetic biology principles to establish new acid production in suitable clostridial chassis strains and mitigate key metabolic bottlenecks hampering high productivity, and b) smart process design and integration to prevent inhibitory effects of the acids produced and the BuOH added in efficient bioprocesses with continuous enzymatic ester product formation and recovery. The project, led by SINTEF, was performed by seven project partners from Norway, UK (2), Germany (3), and France to maximize output of this substantially industry-driven project and share risks, costs and skills. In the final reporting period, SINTEF focused its work on generating and processing research data that should be used for joint publications together with other project partners. This included several fermentation experiments using optimized bacterial strains generated by our partners in Germany and UK, processing of proteome data for improving the metabolic models developed by our partners in Germany, and further work on studying the esterification in the context of integrated process designs by our partners in France. In addition, the project's final workshop was arranged and successfully conducted together with our UK partners. Finalisation of the project was coordinated by SINTEF in close interplay with all project partners.

The BESTER project has been in full support of the ongoing and urgently needed transition to a more sustainable production of commodity chemicals from 2nd generation renewable resources. It has strengthened the position of industrial biotechnology in the production of crucial chemical building blocks for a variety of products and markets and opened new options for Clostridia in bioprocesses that eventually can replace fossil-based production at a competitive price, with low environmental impact, and broad public acceptance. The project further strengthened the position of systems and synthetic biology as powerful tools in the engineering of bacterial production strains for optimised productivity and process stability. For the participating project partners, and SINTEF as the coordinator, the project has enabled new, solid connections across academia, the institute sector, and industry in Europe based on complementary competences and common interest in a more sustainable future.

The specialty chemical industry is a $450 billion market within the $5.4 trillion global chemical market. In this, butyl esters, derivable from n-butanol (BuOH) and suitable organic acids by esterification, have diverse uses as commodity chemicals and biofuels, but also in the fragrance and flavour industry, cosmetics, specialty polymers and coatings. The production of BuOH in the anaerobic clostridial ABE fermentation process is well established. What is needed are efficient processes to produce suitable organic acids from renewable resources for esterification, ideally using enzymes as natural catalysts for entirely green butyl ester formation. The ERA-CoBioTech project BESTER establishes clostridial bioprocesses for an optimized integrated production of a range of different butyl esters using lignocellulosic sugars as a sustainable feedstock for the commodity chemicals market. Efficient organic acid production processes will be developed, linkable to ABE fermentation processes on similar feedstock as a source of BuOH. BESTER will thereby address in a coordinated way the two key handles for efficient production of three different acids, i.e. a) Systems biology driven strain engineering using Synthetic biology principles to establish new acid production in suitable clostridial chassis strains and mitigate key metabolic bottlenecks hampering high productivity, and b) smart process design and integration to prevent inhibitory effects of the acids produced and the BuOH added in efficient bioprocesses with continuous enzymatic ester product formation and recovery. The BESTER project connects six project partners from Norway, UK, Germany, and France to maximise output of this substantially industry-driven project and share risks, costs and skills. Active company involvement will ensure that project results are efficiently taken further towards commercialization. In this way, BESTER will contribute to achieving a sustainable bio-based industrial development in Europe.