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Changes in the structural properties and rate of hydrolysis of cotton fibers during extended enzymatic hydrolysis
Author(s) -
Wang Lushan,
Zhang Yuzhong,
Gao Peiji,
Shi Dongxia,
Liu Hongwen,
Gao Hongjun
Publication year - 2006
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20730
Subject(s) - cellulase , hydrolysis , cellulose , enzymatic hydrolysis , chemistry , hydrogen bond , crystal (programming language) , trichoderma reesei , scanning electron microscope , chemical engineering , crystallography , materials science , organic chemistry , molecule , composite material , engineering , computer science , programming language
An extended enzymatic hydrolysis of cotton fibers by crude cellulase from Trichoderma pseudokoningii S‐38 is described with characterization of both the enzyme changes of activities and cellulose structure. The hydrolysis rates declined drastically during the early stage and then slowly and steadily throughout the whole hydrolysis process the same trend could be seen during the following re‐hydrolysis process. Morphological and structural changes to the fibers, such as swelling, frequent surface erosion, and variation in the packing and orientation of microfibrils, were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Observation of X‐ray diffraction and IR spectra suggests that the hydrolysis process results in a gradual increase in the relative intensity of the hydrogen bond network, and a gradual decrease in the apparent crystal size of cellulose. The I α crystal phase was hydrolyzed more easily than was the I β crystal phase. Apart from the inactivation of CBHs activity, changes in the packing and arrangement of microfibrils and the structural heterogeneity of cellulose during hydrolysis could be responsible for the reduction in the rate of reaction, especially in its later stages. The results indicate that the enzymatic hydrolysis of cellulose occurs on the outer layer of the fiber surface and that, following this, the process continues in a sub‐layer manner. © 2005 Wiley Periodicals, Inc.