BaPro – Bacteroidota for production of probiotics, bioactive substances and organic acids from renewable resources
Bacteroidota belong to one of the most abundant phyla inhabiting the human and animal gastro-intestinal tract. There they provide beneficial functions for the host, for example by the degradation of indigestible dietary fibers and production of useful substances such as acetate and propionate (Thomas et al., 2011). Within the joined project BaPro, funded by the BMBF, our group investigates the potential of bacteria belonging to the phylum Bacteroidota for degradation of biopolymers and for production of propionate.
For the degradation of complex polysaccharides, Bacteroidota possess so called “polysaccharide utilization loci” (PULs) in their genome, which encode for genes involved in sensing, depolymerization and uptake of the breakdown products of a specific polysaccharide (Grondin et al., 2017). The ability to target a variety of plant cell wall components is a well-known feature of gut Bacteroidota PULs and is a rapidly evolving field of research in these days (Hao et al., 2021). With regard to the increasing numbers of predicted PULs and their putative targets, this group of bacteria harbours a huge potential for the identification of new enzymatic functions (Lapébie et al., 2019).
In order to identify strains that efficiently degrade plant polymers and convert them to organic acids, we screened anaerobic Bacteroidota for the utilization of different classes of plant-based polymers. By comparison of the substrate turnover and the product formation of selected species we aim to identify strains that show an especially fast polymer degradation as well as the enzymes involved in this process.
Bacteroidota are also promising for their ability to produce organic acids, specifically succinate and propionate. The latter is an important precursor for a variety of products in food-, medical- and textile-industry and can even be used for the production of bioplastics (Samel et al., 2018). Around 450 000 t are produced every year via petrochemical pathways, but an effective biochemical production from renewable resources has not yet met industrial standards. (Gonzalez-Garcia et al., 2017)
Propionate producing Bacteroidota utilize the succinate-pathway. While the general mechanisms are understood (Macy et al., 1987), further investigation needs to be done to understand dependencies and regulations as well as to improve genetic tools for this group. For this we have started out by screening strains for their propionate production and are now working on different fermentation conditions and genetic systems for selected model organisms to improve yield and titre of the propionate fermentation.
In addition to the examination of known species, new isolates are obtained from environmental samples and screened for the degradation of polymeric substrates and propionate production to find promising new candidates for further research.
Team members involved @ University of Rostock:
Prof. Dr. Mirko Basen
M.Sc. Carolin Döring
M.Sc. Sonja Elisabeth Kurrer
Partners
→ Universität Hamburg (Prof. Dr. Wolfgang Streit)
→ Rheinische Friedrich-Wilhelms-Universität Bonn (Prof. Dr. Uwe Deppenmeier)
→ Christian-Albrechts-Universität zu Kiel (Prof. Dr. Ruth Schmitz-Streit)
→ Universität Rostock (Prof. Dr. Mirko Basen)
→ Carl von Ossietzky Universität Oldenburg (Prof. Dr. Ralf Rabus)
→ RWTH Aachen (Prof. Dr.-Ing. Jochen Büchs)
→ Novozymes Berlin GmbH (Dr. Thomas Polakowski)
References
Basen, M. and Kurrer, S.E. (2020) A close look at pentose metabolism of gut bacteria. FEBS J.288: 1804–1808.
Gonzalez-Garcia, R.; McCubbin, Tim; Navone, Laura; Stowers, Chris; Nielsen, Lars; Marcellin, Esteban (2017): Microbial propionic acid production. Fermentation 3: 21.
Grondin, J.M.; Tamura, K.; Déjean, G.; Abbott, D.W.; Brumer, H. (2017): Polysaccharide utilization loci: fueling microbial communities. J Bacteriol.199: e00860-16.
Hao, Z.; Wang, X.; Yang, H.; Tu, T.; Zhang, J.; Luo, H.; Huang, H.; Su, X. (2021) PUL-mediated plant cell wall polysaccharide utilization in the gut Bacteroidetes. Int J Mol Sci.22: 3077.
Lapébie, P.; Lombard, V.; Drula, E.; Terrapon, N.; Henrissat, B. (2019) Bacteroidetes use thousands of enzyme combinations to break down glycans. Nat Commun.10: 2043.
Macy, J. M.; Ljungdahl, L. G.; Gottschalk, G. (1978): Pathway of succinate and propionate formation in Bacteroides fragilis. J Bacteriol.134: 84-91.
Samel, U-R; Kohler, W.; Gamer, A. O., Keuser, U.; Yang, S-T; Jin Y.; Lin, M.; Wang, Z.; Teles, J. H. (2018) Propionic acid and derivatives. In: Ullmann´s Encyclopedia of Industrial Chemistry. Wiley-VCH, Weinheim, Germany.
Thomas, F.; Hehemann, J-H.; Rebuffet, E.; Czjzek, M.; Michel, G. (2011): Environmental and gut Bacteroidetes: the food connection. Front Microbiol.2.
