Synergistic Activity of Plant Extracts with Microbial Cellulases for the Release of Free Sugars
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Agricultural lignocellulosic waste such as corn stover is a potential source of inexpensive, abundant, and renewable biomass for the production of bioethanol. The enzymatic process for the economically viable breakdown of cellulose to ethanol relies on the availability of inexpensive microbial cellulases. Although the cost of cellulase has decreased in recent years, current costs still preclude the production of economically viable bioethanol from lignocellulose. Substantive efforts in this lab are being directed to transgenic production of cellulases in maize in order to boost efficiency both of production of enzymes and degradation of corn stover. We serendipitously observed that the addition of non-transgenic maize seed extracts to cellulose and microbial enzymes potentiated free sugar release by as much as 20-fold. Further, this synergistic effect between cellulase enzymes and extract was seen with a variety of plant species and tissue extracts, but varied in efficiency, and was optimal at low concentrations of cellulases. Although the nature of the synergistic molecule is not known, the use of extracts to potentiate cellulose breakdown provides opportunities for a clearer mechanistic understanding of the degradation process as well as an economical way to improve the efficiency of cellulases to produce more cost-effective bioethanol from agricultural waste.
KeywordsBioethanol Cellulase Maize Lignocellulose Synergism
Celluclast commercial cellulase enzyme
Control seed extract
This work was supported by a grant from the US Dept. of Energy (DE FG36 GO88025) with cost share from the Wal-Mart Foundation, the Walton Family Foundation, and Arkansas State University. We would also like to thank Nassim Naderi for her expert technical assistance and Dr. Vidya Rajan for help with preparation of the manuscript. JC was sponsored by the Department of the Navy, Office of Naval Research, under Award # N00014-08-1-1209.
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