Mhlongo S.I., den Haan R., Viljoen-Bloom M., van Zyl W.H.
Department of Microbiology, University of Stellenbosch, Stellenbosch, South Africa; Department of Biotechnology, University of the Western Cape, Bellville, South Africa
Mhlongo, S.I., Department of Microbiology, University of Stellenbosch, Stellenbosch, South Africa; den Haan, R., Department of Biotechnology, University of the Western Cape, Bellville, South Africa; Viljoen-Bloom, M., Department of Microbiology, University of Stellenbosch, Stellenbosch, South Africa; van Zyl, W.H., Department of Microbiology, University of Stellenbosch, Stellenbosch, South Africa
In this study, we monitored the inhibition and deactivation effects of various compounds associated with lignocellulosic hydrolysates on individual and combinations of cellulases. Tannic acid representing polymeric lignin residues strongly inhibited cellobiohydrolase 1 (CBH1) and β-glucosidase 1 (BGL1), but had a moderate inhibitory effect on endoglucanase 2 (EG2). Individual monomeric lignin residues had little or no inhibitory effect on hydrolytic enzymes. However, coniferyl aldehyde and syringaldehyde substantially decreased the activity of CBH1 and deactivated BGL1. Acetic and formic acids also showed strong inhibition of BGL1 but not CBH1 and EG2, whereas tannic, acetic and formic acid strongly inhibited a combination of CBH1 and EG2 during Avicel hydrolysis. Diminishing enzymatic hydrolysis is largely a function of inhibitor concentration and the enzyme-inhibitor relationship, rather than contact time during the hydrolysis process (i.e. deactivation). This suggests that decreased rates of hydrolysis during the enzymatic depolymerisation of lignocellulosic hydrolysates may be imparted by other factors related to substrate crystallinity and accessibility. © 2015 Elsevier Inc.
Enzyme inhibition; Enzymes; Flavonoids; Formic acid; Hydrolysis; Lignin; Cellobiohydrolase 1; Cellulases; Deactivation; Enzyme inhibitors; Hydrolysis process; Inhibitor concentration; Inhibitory effect; Lignocellulosic hydrolysates; Enzymatic hydrolysis; beta glucosidase; cellulose 1,4 beta cellobiosidase; enzyme inhibitor; formic acid; formic acid derivative; glucan synthase; lignocellulosic hydrolysate inhibitor; tannin; unclassified drug; Article; enzyme activity; enzyme inactivation; enzyme inhibition; enzyme purification; hydrolysis; nonhuman; polymerization; Saccharomyces cerevisiae