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Microwave pretreatment of substrates for cellulase production by solid-state fermentation
Xuebing Zhao1, Yujie Zhou, Guangjian Zheng
1Department of Chemical Engineering, Institute of Applied Chemistry, Tsinghua University, Beijing 100084, China.
Applied Biochemistry and Biotechnology
|May 20, 2009
Summary
Microwave irradiation and alkali pretreatment enhanced cellulase production from agricultural residues like rice hulls. Combined pretreatment significantly boosted enzyme yields and reducing sugar content for improved biomass utilization.
Area of Science:
- Biotechnology
- Agricultural Science
- Enzyme Engineering
Background:
- Agricultural residues such as wheat bran and rice hulls are abundant lignocellulosic biomass.
- Cellulase enzymes are crucial for biofuel production and biomass conversion.
- Solid-state fermentation (SSF) is an effective method for microbial enzyme production.
Purpose of the Study:
- To investigate the effectiveness of microwave irradiation and alkali pretreatment on agricultural residues for enhanced cellulase production using Trichoderma sp.
- To optimize pretreatment conditions for maximizing cellulase yield and reducing sugar content.
- To evaluate the combined effect of alkali and microwave pretreatment (APCMP) on rice hulls.
Main Methods:
- Solid-state fermentation (SSF) of wheat bran and rice hulls using Trichoderma sp. 3.2942.
- Pretreatment of substrates using microwave irradiation at varying power and time.
- Combined alkali and microwave pretreatment (APCMP) of rice hulls.
- Measurement of cellulase activities (filter paper activity, carboxymethylcellulase activity) and reducing sugar content (RSC).
Main Results:
- Microwave pretreatment alone showed no significant effect on cellulase production, despite initial reducing sugar content decrease.
- Combined alkali and microwave pretreatment (APCMP) of rice hulls significantly increased cellulase yields and reducing sugar production.
- APCMP treatment resulted in a 35.2% increase in filter paper activity, 21.4% in carboxymethylcellulase (CMC)ase, and 13% in RSC compared to untreated rice hulls.
- Fermented residues pretreated with APCMP yielded higher cellulase and reducing sugars than fresh rice hulls.
Conclusions:
- Microwave irradiation primarily increases substrate accessibility by disrupting the rigid structure of rice hulls.
- Alkali pretreatment and APCMP are highly effective due to delignification and ash removal, enhancing substrate acceptability.
- APCMP is a promising strategy for maximizing cellulase and reducing sugar yields from lignocellulosic agricultural residues.
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