To convert corn stover and switchgrass into biofuel, the plant fibres must first be broken down into sugars. But cell wall polymers are cross-linked in various ways that make them very resistant to breaking down, according to Dominic Wong, a chemist at the USDA Agricultural Research Service (ARS) Western Regional Research Center in Albany, California.
Previous studies have shown that a special group of enzymes known as feruloyl esterases (FAEs) are capable of breaking apart key links between the polymers and that the enzymes are produced by certain types of microbes that degrade plant materials.
Wong collected the microbial population from a cow’s rumen and screened their genetic compositions to find genes that produce the FAE enzymes.
Working with scientific partners at Cargill, Wong then isolated, sequenced and cloned 12 genes capable of being introduced into Escherichia coli for production of the enzymes, which can then be used to break loose the polymeric network in the plant cell wall. Wong and the Cargill team have filed a provisional patent application on the FAE genes and enzymes.
In addition to increasing the efficiency of processes that convert biomass to biofuel, the enzymes could also be used to enhance the digestibility and the nutritional qualities of animal feeds.