Monday, April 19, 2010
LL Conference Facility (Hilton Clearwater Beach)
Conversion of lignocellulosic biomass to biofuels requires efficient cell wall degrading enzymes at low cost. One promising approach is to produce enzymes by using their designated degradation target biomass as growth carbon source and presumably also an enzyme inducer for the production organism. This approach assumes that the acclimation of the cellulolytic microorganism to the complex target biomass will produce enzymes better suited to breaking down the biomass. To test this hypothesis, the aerobic fungus Trichoderma reesei was grown on four different substrates to represent different recalcitrance indexes, one highly processed commercial crystalline cellulose (i.e., Avicel), and three others that were much more nearly “native”, i.e., corn stover, switchgrass and yellow poplar that had simply been milled and washed with water and ethanol. Enzymatic activities of up to 17-day growth broths were analyzed on substrates: (1) cellulose such as Avicel for cellulase, (2) xylan for xylanase, and (3) complex biomass substrates. The observed overall rates of sugar-release and the relative rates of release of specific sugars are used to select the optimal pairings of enzymes and their target complex biomass substrates.