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Deactivation of cellulases by phenols
Eduardo Ximenes1, Youngmi Kim, Nathan Mosier
1Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, IN 47907-2022, United States.
Enzyme and Microbial Technology
|November 25, 2011
Summary
Phenolic compounds released during lignocellulosic material pretreatment inhibit and deactivate enzymes crucial for cellulose-to-ethanol conversion. Tannic acid severely damages cellulases and beta-glucosidases, impacting biofuel production efficiency.
Area of Science:
- Biotechnology
- Biochemical Engineering
- Renewable Energy
Background:
- Pretreatment of lignocellulosic biomass can generate inhibitory compounds that hinder enzymatic hydrolysis.
- Phenolic compounds are identified as major inhibitors and deactivators of cellulase enzymes.
- Efficient conversion of cellulose to ethanol relies on effective enzymatic hydrolysis.
Purpose of the Study:
- To identify specific phenolic compounds that inhibit or deactivate cellulase enzymes.
- To quantify the deactivation effects of various phenols on cellulases and beta-glucosidases.
- To compare the resistance of enzymes from different microorganisms to phenolic inhibition and deactivation.
Main Methods:
- Phenolic compounds were tested for their inhibitory effects by immediate addition to enzyme-substrate assays.
- Deactivation effects were assessed by pre-incubating phenols with cellulases or beta-glucosidases before enzyme assays.
- Enzyme activity was measured after pre-incubation periods to quantify inhibition and deactivation levels.
Main Results:
- Tannic, gallic, hydroxy-cinnamic, and 4-hydroxybenzoic acids, along with vanillin, caused 20-80% deactivation of enzymes after 24h.
- Enzymes pre-incubated in buffer alone maintained full activity, confirming phenol-induced deactivation.
- Beta-glucosidase from Aspergillus niger showed higher resistance to inhibition and deactivation compared to enzymes from Trichoderma reesei.
- Tannic acid was identified as the most potent phenolic inhibitor and deactivator across all tested enzyme activities.
Conclusions:
- Phenolic compounds significantly inhibit and deactivate cellulase enzymes essential for biofuel production.
- Enzyme resistance varies based on the source microorganism and the specific phenolic compound.
- Tannic acid poses a substantial challenge to efficient cellulose-to-ethanol conversion due to its strong inhibitory and deactivating properties.
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