In situ measurements of oxidation–reduction potential and hydrogen peroxide concentration as tools for revealing LPMO inactivation during enzymatic saccharification of cellulose
Open Access
- 18 February 2021
- journal article
- research article
- Published by Springer Science and Business Media LLC in Biotechnology for Biofuels
- Vol. 14 (1), 1-10
- https://doi.org/10.1186/s13068-021-01894-1
Abstract
Biochemical conversion of lignocellulosic biomass to simple sugars at commercial scale is hampered by the high cost of saccharifying enzymes. Lytic polysaccharide monooxygenases (LPMOs) may hold the key to overcome economic barriers. Recent studies have shown that controlled activation of LPMOs by a continuous H2O2 supply can boost saccharification yields, while overdosing H2O2 may lead to enzyme inactivation and reduce overall sugar yields. While following LPMO action by ex situ analysis of LPMO products confirms enzyme inactivation, currently no preventive measures are available to intervene before complete inactivation. Here, we carried out enzymatic saccharification of the model cellulose Avicel with an LPMO-containing enzyme preparation (Cellic CTec3) and H2O2 feed at 1 L bioreactor scale and followed the oxidation–reduction potential and H2O2 concentration in situ with corresponding electrode probes. The rate of oxidation of the reductant as well as the estimation of the amount of H2O2 consumed by LPMOs indicate that, in addition to oxidative depolymerization of cellulose, LPMOs consume H2O2 in a futile non-catalytic cycle, and that inactivation of LPMOs happens gradually and starts long before the accumulation of LPMO-generated oxidative products comes to a halt. Our results indicate that, in this model system, the collapse of the LPMO-catalyzed reaction may be predicted by the rate of oxidation of the reductant, the accumulation of H2O2 in the reactor or, indirectly, by a clear increase in the oxidation–reduction potential. Being able to monitor the state of the LPMO activity in situ may help maximizing the benefit of LPMO action during saccharification. Overcoming enzyme inactivation could allow improving overall saccharification yields beyond the state of the art while lowering LPMO and, potentially, cellulase loads, both of which would have beneficial consequences on process economics.Keywords
Funding Information
- Norges Forskningsråd (256766, 257622)
- Lund University
This publication has 32 references indexed in Scilit:
- Harnessing the potential of LPMO-containing cellulase cocktails poses new demands on processing conditionsBiotechnology for Biofuels, 2015
- Catalase improves saccharification of lignocellulose by reducing lytic polysaccharide monooxygenase-associated enzyme inactivationBiotechnology Letters, 2015
- The addition of accessory enzymes enhances the hydrolytic performance of cellulase enzymes at high solid loadingsBioresource Technology, 2015
- Effects of Lytic Polysaccharide Monooxygenase Oxidation on Cellulose Structure and Binding of Oxidized Cellulose Oligomers to CellulasesThe Journal of Physical Chemistry B, 2015
- Cellulose Surface Degradation by a Lytic Polysaccharide Monooxygenase and Its Effect on Cellulase Hydrolytic EfficiencyOnline Journal of Public Health Informatics, 2014
- Production of four Neurospora crassa lytic polysaccharide monooxygenases in Pichia pastoris monitored by a fluorimetric assayBiotechnology for Biofuels, 2012
- Production and effect of aldonic acids during enzymatic hydrolysis of lignocellulose at high dry matter contentBiotechnology for Biofuels, 2012
- An Oxidative Enzyme Boosting the Enzymatic Conversion of Recalcitrant PolysaccharidesScience, 2010
- Progress and Challenges in Enzyme Development for Biomass UtilizationPublished by Springer Science and Business Media LLC ,2007
- Ascorbic Acid Oxidation by Hydrogen PeroxideAnalytical Biochemistry, 1998