Oxidation is a versatile method to modify cellulose material properties, used in range of applications from cosmetics to papermaking. Biocatalytic oxidation, using enzymes as catalysts, is an interesting opportunity due to the low energy consumption and reduced waste formation, as well as environmental safety of the protein-based catalysts. However, for a long time there were no known enzymes able to do this, although indications that presence of oxygen can have positive effect on cellulose degradation by microbial enzyme cocktails existed. Around 10 years ago, a new enzyme type was discovered: lytic monosaccharide monooxygenases (LPMOs), enzymes which can oxidize not only cellulose, but also chitin, hemicelluloses and starch, depending on the enzyme variant. This discovery had not only scientific, but also technical impact, since these enzymes can have a huge positive effect on efficiency of lignocellulose saccharification needed in biofuel biorefineries.
Beyond the biofuel and chemical sector, the LPMOs offer tools to biocatalytic oxidation of cellulose for material applications. As in any new technology, many fundamental aspects need to be understood before the targets of application requirements can be reached. These have been elucidated in a FinnCERES-funded project Enzymatic modification of lignocellulose building blocks & cellulose surfaces modelling and related project From fundamentals to valorization: Enzymatic oxidation of cellulosic fibres and underlying mechanisms (FunEnzFibres) funded in European Co-fund action ERA-Net ForestValue.
Figure 1: Biocatalytic oxidation of cellulose for material applications can be obtained by lytic monosaccharide monooxygenases (LPMOs). Computational modelling reveals molecular level interactions and changes resulting from the enzyme processing.
Molecular modelling figure credits: Maisa Vuorte, Soft Materials Modelling Group, Aalto University. Photographs of fermentors&pulps: VTT image bank. Trichoderma culture: Nina Aro. Nanocellulose & dissolving fibre: Panu Lahtinen & Ulla Holopainen-Mantila.