Quantification of bound and free enzymes during enzymatic hydrolysis and their reactivities on cellulose and lignocellulose

•Bound enzymes are primarily responsible for enzymatic hydrolysis.•Free enzymes become insignificant for enzyme hydrolysis after a certain time.•The loss of synergistic effect in free enzymes limits digestibility of free enzymes.•Tween 80 assists releasing CBH I into free enzymes.•With surfactant, t...

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Bibliographic Details
Published in:Bioresource technology 2013-11, Vol.147, p.369-377
Main Authors: Yu, Zhiying, Jameel, Hasan, Chang, Hou-min, Philips, Richard, Park, Sunkyu
Format: Article
Language:English
Subjects:
Biological and medical sciences
Biomass
Biotechnology
Bound and free enzyme
Cellulose
Cellulose - metabolism
Electrophoresis, Polyacrylamide Gel
Enzymatic hydrolysis
Enzymes - metabolism
Fundamental and applied biological sciences. Psychology
Hydrolysis
Lignin - metabolism
Lignocellulose
Synergistic effect
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Summary:•Bound enzymes are primarily responsible for enzymatic hydrolysis.•Free enzymes become insignificant for enzyme hydrolysis after a certain time.•The loss of synergistic effect in free enzymes limits digestibility of free enzymes.•Tween 80 assists releasing CBH I into free enzymes.•With surfactant, the digestibility of free enzymes on Avicel was greatly enhanced. Enzymatic hydrolysis of insoluble biomass is a surface reaction. Part of the enzyme adsorb on the surface of biomass, whereas the others stay in the liquid phase. In this study, three substrates (Avicel cellulose, bleached hardwood pulp, and green-liquor pretreated hardwood pulp) were used to study the reactivity of bound and free enzyme. In a continuous enzymatic hydrolysis, 35–65% initially added enzymes became bound enzymes, which were primarily responsible for enzymatic hydrolysis. The contribution from free enzymes became insignificant after a certain period of reaction time. SDS–PAGE analysis showed that CBH I was significantly decreased in the free enzyme, which might be the reason for the low digestibility of free enzymes due to the loss of synergistic effect. When Tween 80 was added during enzymatic hydrolysis, the digestibility of free enzyme on Avicel was greatly enhanced. However, the benefit of surfactant was not noticeable for lignocellulosic pulps, comparing to Avicel.
ISSN:0960-8524
1873-2976
DOI:10.1016/j.biortech.2013.08.010