preprints.org > biology and life sciences > biochemistry and molecular biology > doi: 10.20944/preprints202012.0120.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 3 December 2020 / Approved: 6 December 2020 / Online: 6 December 2020 (18:15:08 CET)

Cellulose is the most abundant polysaccharide in lignocellulosic biomass, where it is interlinked with lignin and hemicellulose. Bioethanol can be produced from biomass. Because breaking down biomass is difficult, cellulose-active enzymes secreted by filamentous fungi play an important role in degrading recalcitrant lignocellulosic biomass. We characterized a cellobiohydrolase (AfCel6A) and lytic polysaccharide monooxygenase LPMO (AfAA9_B) from A. fumigatus after they were expressed in Pichia pastoris and purified. The biochemical parameters suggested that the enzymes were stable; the optimal temperature was ~60 °C. Further characterization revealed high turnover numbers (kcat of 147.9 s-1 and 0.64 s-1, respectively). Surprisingly, when combined, AfCel6A and AfAA9_B did not act synergistically. Association of AfCel6A and AfAA9_B inhibits the activity of AfCel6A, an outcome that needs to be further investigated. However, addition of AfCel6A or AfAA9_B boosts the enzymatic saccharification activity of a cellulase cocktail and the activity of cellulase Af-EGL7. The supplementation of an enzymatic cocktail with AfCel6A or AfAA9_B boosted the yield of fermentable sugars from complex substrates, especially sugarcane exploded bagasse, by up to 95%. The synergism between the cellulase cocktail and AfAA9_B is enzyme- and substrate-specific, which suggests a specific enzymatic cocktail for each biomass.

GH6 cellobiohydrolase; AA9 LPMO; lignocellulose hydrolysis; bioethanol

Biology and Life Sciences, Biochemistry and Molecular Biology

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