RECYCLE OF CELLULASES AND THE USE OF LIGNOCELLULOSIC RESIDUE FOR ENZYME-PRODUCTION AFTER HYDROLYSIS OF STEAM-PRETREATED ASPENWOOD

Various modes of substrate and enzyme addition were used to hydrolyze a 10% concentration (w/v) of steam-exploded, water-and-alkali extracted aspenwood with Trichoderma harzianum E58 cellulases. Although cellulose conversion was high (94-100%), enzyme recovery was low in all cases. Low enzyme recovery was due to a combination of thermal inactivation and adsorption of the cellulases onto the lignocellulosic residue. Enzyme recycle was not feasible as the activity of the recovered cellulases towards crystalline cellulose was low. However, the residual material from enzyme hydrolysis was a suitable carbon source for cellulase enzyme production by T. harzianum based on enzyme yield and hydrolytic potential. These residues could only be used up to a 1% substrate concentration, since at higher substrate loadings cellulase production was reduced, likely because of lignin inhibitors.