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Roles of extracellular lactose hydrolysis in cellulase production by Trichoderma reesei Rut C30 using lactose as inducing substrate

Paper ID Volume ID Publish Year Pages File Format Full-Text
34969 45064 2010 10 PDF Available
Title
Roles of extracellular lactose hydrolysis in cellulase production by Trichoderma reesei Rut C30 using lactose as inducing substrate
Abstract

Lactose, an inexpensive, soluble substrate, offers reasonably good induction for cellulase production by Trichoderma reesei. The fungus does not uptake lactose directly. Lactose is hydrolyzed to extracellular glucose and galactose for subsequent ingestion. The roles of this extracellular hydrolysis step were investigated in this study. Batch and continuous cultures were grown on the following substrates: lactose, lactose–glycerol mixtures, glucose, galactose, and glucose–galactose mixtures. Cell growth, substrate consumption, lactose hydrolysis, and lactase and cellulase production were followed and modeled. Cells grew much faster on glucose than on galactose, but with comparable cell yields. Glucose (at >0.3 g/L) repressed the galactose consumption. Cellulase synthesis was growth-independent while lactase synthesis was growth-dependent, except at D < ∼0.065 h−1 where a basal level lactase production was observed. For cellulase production the optimal D was 0.055–0.065 h−1 where the enzyme activity and productivity were both near maxima. The model suggested that lactase synthesis was subject to weak galactose repression. As the galactose concentration increased at high D (>0.1 h−1), lactase synthesis became repressed. The insufficient lactase synthesis limited the lactose hydrolysis rate. Extracellular lactose hydrolysis was concluded to be the rate-limiting step for growth of T. reesei Rut C30 on lactose.

Keywords
Cellulase; Lactase; β-Galactosidase; Induction; Repression; Lactose
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Roles of extracellular lactose hydrolysis in cellulase production by Trichoderma reesei Rut C30 using lactose as inducing substrate
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 45, Issue 9, September 2010, Pages 1494–1503
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us