Developing ecological and sustainable ways to convert biomass side-streams and industrial wastes to valuable products is a key challenge in our modern society and hence constitutes a central focus in Bioeconomy. In the BioSC BoostFund project PectiLyse we therefore aimed on establishing the prerequisites for a consolidated bioprocess using Ustilago maydis. More specifically, this model fungus should be engineered for efficient degradation of pectin-rich industrial side-streams. The released monosaccharides should subsequently be converted to the organic acid itaconic acid, a promising platform chemical for the production of biofuels, plastics or cement additives.
To achieve this, intrinsic carbohydrate-activating enzymes were produced in the biotechnologically relevant yeast stage of the fungus. To complement the limited pectinolytic repertoire of U. maydis, potent heterologous pectinases were introduced which were derived not only from fungal but also from bacterial sources. This strategy enabled the degradation and metabolization of the main pectin backbone polygalacturonic acid. Enzymes attacking the complex pectin side-chains were also addressed. For example, a complementary set of five intrinsic arabinofuranosidases was characterized which showed complementary activities towards different arabinan substrates. On the product side, a limiting factor of itaconic acid production was identified with the activity of the transcription factor Ria1 which controls the itaconic acid biosynthesis cluster. Importantly, insertion of a constitutively expressed version of the respective gene enabled constantly high itaconic acid titers in previously inactive strain backgrounds. In the near future, this will allow combining the biomass degrading abilities of U. maydis with the production of itaconic acid in a consolidated bioprocess. In parallel, key steps were also undertaken to enable an efficient bioprocess from the technical perspective. Specifically, the respiratory quotient determined in RAMOS devices proofed a potent means for online characterization of metabolic activity towards complex substrates like polygalacturonic acid. This serves as a basis for high-throughput cultivation studies in which optimal conditions for the simultaneous saccharification and fermentation of organic acids or other valuable compounds will be established.
Participating Core Groups
Dr. K. Schipper and Prof. Dr. M. Feldbrügge, Institute for Microbiology, HHU Düsseldorf
Dr. N. Wierckx and Prof. Dr. L. M. Blank, Institute of Applied Microbiology, RWTH Aachen University
Dr. T. Schlepütz and Prof. Dr.-Ing. J. Büchs, Aachener Verfahrenstechnik, RWTH Aachen University
Industrial partner: Pfeifer & Langen GmbH Co. KG, 50835 Köln
Dr. K. Schipper
Institute for Microbiology
Heinrich-Heine University Düsseldorf
Building 26.12.01 Room 64
01.11.2015 – 31.10.2017
The total budget of PectiLyse is € 441.327,00. PectiLyse is part of the NRW-Strategieprojekt BioSC and thus funded by the Ministry of Innovation, Science and Research of the German State of North Rhine-Westphalia.
Geiser, E, Ludwig, F, Zambanini, T, Wierckx, N and Blank, LM (2016). Draft genome sequences of itaconate-producing ustilaginaceae. Genome Announc 4(6).
Geiser, E, Przybilla, SK, Engel, M, Kleineberg, W, Buttner, L, Sarikaya, E, Hartog, TD, Klankermayer, J, Leitner, W, Bolker, M, Blank, LM and Wierckx, N (2016). Genetic and biochemical insights into the itaconate pathway of ustilago maydis enable enhanced production. Metab Eng 38: 427-435.
Geiser, E, Reindl, M, Blank, LM, Feldbrugge, M, Wierckx, N and Schipper, K (2016). Activating intrinsic carbohydrate-active enzymes of the smut fungus ustilago maydis for the degradation of plant cell wall components. Appl Environ Microbiol 82(17): 5174-5185.