The aim of iBiomass is to evaluate the impact of cell wall changes in corn brought about by infection on processing of the lignocellulose in the OrganoCat technology. Smut fungal infections are used as an example, since they occur at low incidence in corn fields in Germany, which is not detrimental to yield, but entails changes in downstream processing of the biomass e.g. in silage conditions.
Infected material was produced in WP1. Here, seedling infections in corn were carried out with several strains of the model smut fungus Ustilago maydis to produce large amounts of infected material under controlled conditions rapidly. Healthy and infected material was harvested and ground, and then passed on in small aliquots to WP2 for an analysis of the lignocellulose composition. Notably, infection brings about several changes. Starch and cellulose content are reduced possibly due to the activity of the fungus as an additional sink. By contrast, the lignin content and total wall acetate is increased, which might point to cell wall strengthening as part of the plant defense program. Overall, infection leads to a reduced saccharification yield of the biomass, and hence a challenge for processing of the maize biomass. To gain insight into the connection between lignocellulose composition and infection, a mutant with a high saccharification yield, Cal-1, (provided by core group Pauly) was tested for enhanced susceptibility to fungal infection in WP1. Consistent with yield data from field trials, where only natural pathogen pressure was present, the Cal-1 mutant is not more susceptible to U. maydis. Processing of infected material in the OrganoCat technology was tested in WP3. Initial results indicate improved accessibility of infected material to the OrganoCat pre-treatment. Pre-treatment can be carried out at shorter times. The resulting hydrolysate and pulp from infected and healthy material are now being analyzed for composition and saccharification yield in WP2. With regard to the timeline, the project overall is in schedule with minor changes as indicated for the individual WPs. Importantly, exchange of material is well-established, and common conditions for drying and grinding the plant material have been established. Molecular data raised in WP1 on mutant analyses (fungal and plant mutants) will in the future provide the mechanistic details to understand the chemical changes brought about in the infection. In particular, the increased lignin content in the plant cell wall observed in WP2 was surprising, since U. maydis possesses an effector protein that is supposed to suppress lignin formation. WP3 only started in April and has already revealed first adaptations to infection in the OrganoCat processing. Upon completion of iBiomass in October 2019, a critical follow-up will be confirmation of the detected effects also with material from adult plants and from field infection. Only with agronomically relevant samples, we will be able to scale up the processing for improved biomass use in bioeconomy.
Dr. V. Göhre
CG M. Feldbrügge
Heinrich Heine University Düsseldorf
phone: +49 211 8111529
Dr. V. Ramirez; CG M. Pauly, Plant Cell Biology and Bioechnology, Heinrich Heine University Düsseldorf
Prof. W. Leitner, Technical Chemistry and Petrochemistry, RWTH Aachen University
01.11.2018 - 31.10.2019
The total budget of iBiomass is 139,630 €. iBiomass is is part of the NRW-Strategieprojekt BioSC and thus funded by the Ministry of Culture and Science of the German State of North Rhine-Westphalia.