Microscopic examination of changes of plant cell structure in corn stover due to hot water pretreatment and enzymatic hydrolysis

• Published in: Biotechnology and bioengineering 2007-06, Vol.97 (2), p.265-278
• Main Authors: Zeng, Meijuan, Mosier, Nathan S., Huang, Chia-Ping, Sherman, Debra M., Ladisch, Michael R.
• Format: Article
• Language: English
• Subjects: accessible surface area; Biological and medical sciences; Biotechnology; Cells; Cellulase - metabolism; Cellulase - pharmacology; Cellulose - metabolism; Chemical reactions; Corn; corn stover; enzymatic hydrolysis; Enzymes; Flowers & plants; Fundamental and applied biological sciences. Psychology; Glucose - chemistry; glucose conversion; Hot Temperature; hot water pretreatment; Hydrolysis; Microscopy, Electron, Scanning; particle size; Plant Leaves - drug effects; Plant Leaves - ultrastructure; Plants; SEM image; Water; Water treatment; Zea mays - anatomy & histology; Zea mays - drug effects
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.21298

Particle size associated with accessible surface area has a significant impact on the saccharification of plant cell walls by cellulolytic enzymes. Small particle sizes of untreated cellulosic substrate are more readily hydrolyzed than large ones because of higher specific surface area. Pretreatment enlarges accessible and susceptible surface area leading to enhanced cellulose hydrolysis. These hypotheses were tested using ground corn stover in the size ranges of 425–710 and 53–75 µm. Ultrastructural changes in these particles were imaged after treatment with cellulolytic enzymes before and after liquid hot water pretreatment. The smaller 53–75 µm corn stover particles are 1.5× more susceptible to hydrolysis than 425–710 µm corn stover particles. This difference between the two particle size ranges is eliminated when the stover is pretreated with liquid hot water pretreatment at 190°C for 15 min, at pH between 4.3 and 6.2. This pretreatment causes ultrastructural changes and formation of micron‐sized pores that make the cellulose more accessible to hydrolytic enzymes. Biotechnol. Bioeng. 2007;97: 265–278. © 2006 Wiley Periodicals, Inc.