Cellulose conversion of corn pericarp without pretreatment

Area of Science:

• Biotechnology
• Biochemical Engineering
• Renewable Energy

Background:

• Cellulose hydrolysis is crucial for biofuel production.
• Phenolic compounds released during corn processing inhibit cellulase enzymes.
• Pretreatment of biomass is typically required to overcome inhibition.

Purpose of the Study:

• To investigate direct cellulose hydrolysis in unpretreated corn pericarp.
• To identify enzymes resistant to phenolic inhibition for efficient cellulose conversion.
• To demonstrate a viable pathway for cellulose-ethanol production in existing corn ethanol facilities.

Main Methods:

• Enzyme hydrolysis of unpretreated corn pericarp using a phenol-tolerant Aspergillus niger pectinase preparation.
• Comparison of conversion efficiency with Trichoderma reesei cellulase.
• Analysis of phenol release and its impact on enzyme activity.

Main Results:

• Achieved 98% cellulose conversion in 72 hours with 0.25 FPU/g pericarp solids using A. niger pectinase.
• Significantly lower conversion (16%) observed with Trichoderma reesei cellulase due to phenol sensitivity.
• High conversion was linked to using phenol-resistant enzymes and unground pericarp to minimize phenol release.

Conclusions:

• Direct enzymatic hydrolysis of unpretreated corn pericarp is feasible using phenol-tolerant enzymes.
• Minimizing phenol release by avoiding size reduction is key to high cellulose conversion.
• This approach offers a direct pathway for producing cellulosic ethanol within corn ethanol plants without pretreatment.