title: Lignocellulosic hydrolysate inhibitors selectively inhibit/deactivate cellulase performance.
abstract: 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.
authors.affiliation: Department of Microbiology, University of Stellenbosch, Stellenbosch 7600, South Africa. Electronic address: mhlongo.sizwe8@gmail.com.
authors.forename: Sizwe I
authors.initials: SI
authors.lastname: Mhlongo
authors.affiliation: Department of Biotechnology, University of the Western Cape, Bellville, 7530, South Africa. Electronic address: rdenhaan@uwc.ac.za.
authors.forename: Riaan
authors.initials: R
authors.lastname: den Haan
authors.affiliation: Department of Microbiology, University of Stellenbosch, Stellenbosch 7600, South Africa. Electronic address: mv4@sun.ac.za.
authors.forename: Marinda
authors.initials: M
authors.lastname: Viljoen-Bloom
authors.affiliation: Department of Microbiology, University of Stellenbosch, Stellenbosch 7600, South Africa. Electronic address: whvz@sun.ac.za.
authors.forename: Willem H
authors.initials: WH
authors.lastname: van Zyl
mesh_terms: D018533:Biomass; D001709:Biotechnology; D002480:Cellulase / Q000037:antagonists & inhibitors; D044602:Cellulases / Q000037:antagonists & inhibitors*; D002482:Cellulose / Q000378:metabolism; D043366:Cellulose 1,4-beta-Cellobiosidase / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology; D043326:Glucan 1,3-beta-Glucosidase / Q000037:antagonists & inhibitors; D006868:Hydrolysis; D007700:Kinetics; D008031:Lignin / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D029701:Saccharomyces cerevisiae Proteins / Q000037:antagonists & inhibitors; D013634:Tannins / Q000378:metabolism / Q000493:pharmacokinetics; D001617:beta-Glucosidase / Q000037:antagonists & inhibitors
chemical_list: D004791:Enzyme Inhibitors; D029701:Saccharomyces cerevisiae Proteins; D013634:Tannins; C036909:lignocellulose; D002482:Cellulose; D008031:Lignin; D044602:Cellulases; C056373:endoglucanase 2; D001617:beta-Glucosidase; D002480:Cellulase; C468487:EXG1 protein, S cerevisiae; D043326:Glucan 1,3-beta-Glucosidase; D043366:Cellulose 1,4-beta-Cellobiosidase
keywords: Cellulases; Deactivation; Inhibition; Lignocellulosic hydrolysate