Scientists at the Department of Energy's Los Alamos National Laboratory working with other researchers say a potential pretreatment method can make plant cellulose five times more digestible by enzymes that convert it into ethanol, a useful biofuel.
While biomass is an attractive renewable energy source, the fermentable sugars that are extracted and converted live within a cellulose network in plant cells that's tightly packed and held together with strong hydrogen bonds, making it difficult for enzymes to get at, researchers say.
Currently, ethanol can only be extracted in usable quantities if the biomass is pretreated with costly, potentially toxic chemicals in an energy-intensive process, a DOE release said Wednesday.
Los Alamos researcher S. Gnanakaran and colleagues examined how cellulose changes structurally into an intermediate form that can be enzymatically attacked when pretreated with ammonia.
"Our modeling showed, and the experimental evidence confirmed, that the pretreatment reduced the strength of hydrogen bonds in the cellulosic network," Gnanakaran said.
This significantly reduced the tightness of the cellulose network and left it more open to conversion into sugar by enzymes, he said.
"This work helps address some of the potential cost barriers related to using biomass for biofuels," Gnanakaran said.