Currently, bioethanol is the most promising alternative renewable energy
source to fossil fuels. Bioethanol has the potential to provide sustainable, cost effective
energy while reducing greenhouse gas emissions. The complex lignin-cellulosehemicellulose
matrix of the biomass has to be fractioned and the carbohydrate polymers
need to undergo hydrolysis to yield fermentable sugars. This hydrolysis step is typically
catalyzed by cocktails of enzymes including cellulases, hemicellulases and other
accessory proteins that target and degrade specific constituents of cell wall. The
requirements of enzyme complexes which act synergistically to unlock and saccharify
polysaccharides from the lignocellulose complex to fermentable sugars represent major
costs in the overall process and present a great challenge. Hence, improvements in the
development of economically viable technologies for the production of saccharifying
enzymes are essential for optimizing the biofuel production process. Topics are
summarized from a practical point of view including classification and properties of
cellulases, synergistic action, action mechanisms and accessory proteins as well as the
future trends for cellulase production, applications and biotechnological perspectives of
these enzymes.
Keywords: Accessory proteins, bioethanol, biorefinery, enzymatic hydrolysis,
lignocellulose.
