Fig. 5: LPMO-catalyzed depolymerization of cellulose using organosolv lignin as photoredox catalyst.

The graph shows time courses for the production of oxidized products in photobiocatalytic reactions containing ScAA10C (500 nM), Avicel (10 g L⁻¹), and organosolv lignin (OL) from spruce (S; circles) or birch (B; squares) (2.5 g L⁻¹). All reactions were carried out in sodium phosphate buffer (50 mM, pH 6.0) at 40 °C under magnetic stirring and exposed (orange symbols) or not (white symbols) to visible light (I = 10% I_max, ~16.8 W cm⁻²). The light-exposed reactions were incubated for 1.5 h while the dark reactions were incubated for 24 h. Before quantification of soluble oxidized products, solubilized cello-oligosaccharides were hydrolyzed by TfCel6A to convert LPMO products with varying degree of polymerization (DP) to a mixture of DP 2 and 3 [GlcGlc1A, (Glc)2Glc1A], the amounts of which were summed up to yield the concentration of oxidized sites. The data is presented as mean values obtained from three independent experiments and error bars show ±s.d. (n = 3). OL was prepared as a stock suspension (25 g L⁻¹) in water, and thoroughly mixed prior to adding lignin to the reaction vials.