Enzymes and electrons at work: dual processing of carbohydrates and lignin producing prebiotic oligosaccharides and bioactive lignins

Abstract

One of the challenges facing our society is how food and feed can be produced sustainably in a world of 9 billion people. New knowledge, technology and approaches are needed in to use our agricultural resources more efficiently. The solutions will not provide quantum leaps, but rather incremental changes introducing new technologies for processing biomass to food or feed products. This project will investigate a new class of enzymes and light-driven reaction mechanisms capable of improving the feed value and processing properties of a lignocellulosic feedstock. A new class of enzymes capable of simultaneously processing carbohydrates and lignin has recently been discovered. The enzymes Lytic Polysaccharide Monooxygenases (LPMOs) oxidize the most recalcitrant carbohydrates (such as cellulose, for example) while at the same time abstracting electrons from lignin as part of their catalytic cycle. This dual oxidation mechanism is completely new and opens new possibilities for conversion of agricultural residues into not only fuels but also food and bioactive products.). The carbohydrate oligomers are well characterized, whereas the changes to the lignin structure have only been investigated and exploited rudimentarily. The potential lignin derived compounds are known to have both antioxidant and biocide properties. To function, The LPMOs require an external electron donor. A completely novel and highly relevant aspect of the project is, that the LPMO reactions can be boosted by 10 to 100 times using light combined with photosynthetic pigments and lignin as the electron donating system. This opens possibilities for developing a whole new set of technologies that not only produces unique food and bioactive compounds but also are driven by light, thereby increasing process efficiencies and further reducing environmental impacts. (AU)