Determination of the minimal enzyme cocktails for hydrolysis of Borregaard pre-treated lignocellulosic biomasses

Despite recent progress, enzymatic hydrolysis of many lignocellulosic biomasses is still insufficiently efficient. In this study, we present the optimization of minimal enzyme cocktails for hydrolysis of Norway spruce and bagasse, which were pre-treated with Borregaard’s patented BALI process (1). Minimal enzyme cocktails were composed using several glycoside hydrolases purified from the industrially relevant filamentous fungus Trichoderma reesei, a purified commercial β-glucosidase from Aspergillus niger, and in-house expressed enzymes. The effect of addition of lytic polysaccharide monooxygenases (LPMOs) was also tested, since oxidative cleavage of cellulose by such LPMOs is known to be beneficial for conversion efficiency (2-4). We applied statistically designed mixtures of enzymes, utilizing MODDE Design of Experiments software. The results reveal the relative importance of varying enzyme types in optimal processing of the Borregaard pre-treated biomasses. Results indicate also that the effect of LPMOs on cellulose degradation is substrate dependent. Currently available commercial cellulase cocktails were used for bench-marking.

References:

1) Sjöde A, Frölander A, Lersch M, Rødsrud G. Lignocellulosic biomass conversion, 2013, Patent no. EP2376642

2) Vaaje-Kolstad G, Westereng B, Horn SJ, Liu Z, Zhai H, Sørlie M, Eijsink VG. An oxidative enzyme boosting the enzymatic conversion of recalcitrant polysaccharides. Science 2010; 330: 219-222

3) Horn SJ, Vaaje-Kolstad G, Westereng B, Eijsink VG. Novel enzymes for the degradation of cellulose. Biotechnol Biofuels 2012, 5

4) Aachmann FL, Sørlie M, Skjåk-Bræk G, Eijsink VG, Vaaje-Kolstad G. NMR structure of a lytic polysaccharide monooxygenase provides insight into copper binding, protein dynamics, and substrate interactions. PNAS 2012, 109: 18779–18784