Inhibition of enzyme blend from Chrysoporthe cubensis and Penicillium pinophilum by phenols

Phenolic compounds are known as important inhibitors during enzymatic hydrolysis of lignocellulosic biomass. The Chrysoporthe cubensis:Penicillium pinophilum blend present good synergy and great potential for application in the lignocellulose hydrolysis process. This work identifies the phenols with major inhibition effect on this enzyme blend. The inhibition effects were measured by combining the inhibitors (phenols) with enzyme and substrate immediately at the beginning of the assay. The possible inhibitory effects of various phenolic compounds (tannic, gallic, trans-cinnamic, ferulic, ρ-coumaric and sinapic acids, vanillin and syringaldehyde) were tested at 2.5 Mm. Our results indicated that only CMCase activity was inhibited by all phenolic compounds at 2.5 mM. Tannic acid inhibited the activities measured by the filter paper (28% inhibition), ρ-NPGase (40% inhibition) and ρ-NPCel (28% inhibiton) activity assays. The other phenols tested had little or no inhibition effect. Hemicellulases showed no inhibition at 2.5 mM. However at 5 mM, only tannic acid inhibited β-xylosidase (78%) and β-galactosidase (69%) activities. The strength of the inhibition effect depended on the type of enzyme, the microorganism from which the enzyme was derived, and the type of phenolic compounds present. This work shows that oligomeric phenols represented by tannic acid, promote greater inhibition than monomeric phenols in the same concentration. The dendritic architecture and phenolic composition of tannic acid may contribute significantly to the inhibitory potential of this compound.