Biotechnology Colloquium: Prof. Dr. Bruno Bühler (UFZ Leipzig)

Guest: Prof. Dr. Bruno Bühler (Department of Microbial Biotechnology, Helmholtz Center for Environmental Research GmbH–UFZ, Permoserstraße 15, 04318 Leipzig, Germany)

Title: Microbial biotechnology on the verge of becoming a crucial technology in our future society

Abstract: Microbial biotechnology is considered to offer sustainable solutions for a future bioeconomy – in terms of energy carrier as well as chemicals production. For technically demanding reactions such as oxygenase-catalyzed oxyfunctionalizations or the setup of multistep catalysis schemes (i.e., reaction cascades – orthogonal pathways), living microbial cells offer attractive features such as efficient cofactor regeneration, self-renewal (enzyme synthesis and growth), and handling of reactive oxygen species. Furthermore, the cell membranes enclose a confined microenvironment featuring high reactant and catalyst concentrations. Thus, such whole-cell systems pose big chances as well as challenges in terms of catalyst optimization and process control. Beside technical aspects such as mass transfer and reaction kinetics, a large number of concurrent and highly cross-linked biological processes such as recombinant gene expression, energy metabolism, and toxification have to be considered.

As examples for the production of chemicals, in vivo steroid hydroxylation and cascades for monomer production in engineered Pseudomonads and E. coli will be presented. This includes the efficient production of lactones, ω-hydroxy acids, ω-amino acids, and dioic acids as monomers for a broad set of polyesters and polyamides (nylons), of which conventional production processes often are associated with severe environmental burdens (energy demand, carbon footprint, pollution). For this purpose, Cyp450-, nonheme-iron-, and Baeyer-Villiger monooxygenases as well as different types of dehydrogenase, hydrolases, and transaminases are combined and applied following an integrated approach, in which reaction engineering and strain analysis and optimization are pursued in parallel. On the reaction engineering side, this includes the evaluation and engineering of different biocatalyst formats, mixed species approaches, in situ substrate supply and product extraction schemes, as well as proof of concept DSP.

Beside heterotrophic host strains, we also focus on phototrophs, i.e. cyanobacteria. Thereby, we aim to exploit their capacity to provide high-energy reduction equivalents from water as highly attractive electron donor. The photosynthetic light reaction thereby provides both co-substrates of oxygenases, i.e., electrons and O2. Applying Synechocystis sp. PCC 6803, strain design and application for photosynthesis-driven redox biocatalysis as well as first steps towards multistep biocatalysis will be discussed. Again, reaction engineering options are included. Light-driven biocatalysis based on a CYP450 monooxygenase, a Bayer-Villiger monooxygenase, and an oxygen-tolerant hydrogenase will be highlighted.

For those that can’t make it in person, you can join online on ZOOM (Meeting ID: 775 214 8866 Passcode: PNb7rJ)