On March 13th, the 20th BioSC Lecture took place in the Jülich Research Center. Prof. Dr. Thomas Brück, holder of the Werner Siemens Chair for synthetic biotechnology and director of the AlgaeTec Center at the Technical University of Munich, presented different impressive bioprocesses for fixation, valorization and storage of CO2.
Prof. Brück began by naming urgent global challenges, especially the effects of climate change, that are already noticeable today. In his view, measures to combat climate change have been inadequate largely because economic motivation is too low. He emphasized that scientific questions must lead to economic opportunities. He therefore presented some successful examples from his research.
Many high-quality chemicals and materials are produced on the basis of lipids. Microalgae and yeasts can produce large quantities of lipids without competing with food production and without causing land-use changes, as is the case for palm oil or even rapeseed oil, for example. Prof. Brück presented a patented process in which specific yeasts are co-fermented with hydrolyzed biomass from agricultural residue flows and acetate produced from CO2 and electrolytically obtained hydrogen. As a result of this co-fermentation, yeasts can grow to a high density and produce large quantities of lipids. Water and biomass from the fermentation process are completely recycled and specialized enzymatic hydrolysis of the yeast cells allows a solvent-free lipid extraction. The price of the oil obtained in this way corresponds to the price of eco-certified palm oil and is thus competitive. In terms of life cycle analysis, the oil is within the range of plant oils.
The products to which lipids are processed range from plastics to lubricants and biodiesel up to carbon fibers. Today, the latter are mainly used in automobile production, but they are also suitable for construction elements in buildings or bridges, for example. This represents a highly effective opportunity to fight climate change, explained Prof. Brück. If lipids are produced in algae on a large scale, used in the construction sector and, after use, are ultimately stored in empty coal seams instead of burning them as it is done today, significant quantities of CO2 could be permanently withdrawn from the atmosphere. This approach is deemed globally relevant in the current world climate report and Prof. Brück received an award for this work at the UN World Climate Conference 2018 in Kattowitz.
In addition, Prof. Brück presented two other biosyntheses established in his working group. For the production of the biodegradable plastic polyhydroxybutyrate (PHB) made of wheat bran, the Dahms synthetic pathway from Pseudomonas was introduced into Ralstonia in order to make the xylose in bran available. Ralstonia produces the monomer 3-hydroxybutyric acid that is subsequently polymerized to PHB using a cell-free enzyme cascade. The biodegradable insect repellant cembratrienol can also be produced from wheat bran by a metabolically engineered E.coli strain, which creates new possibilities for plant protection. All examples demonstrated impressive possibilities for establishing a sustainable bioeconomy.