THE SACCHARIFICATION OF CORN STOVER BY CELLULASE FROM PENICILLIUM-FUNICULOSUM

Corn stover, the most abundant agricultural residue produced in the US, was used as substrate for the enzymatic saccharification of cellulose and hemicellulose by a cellulase produced from Penicillium funiculosum. Mechanical pretreatment to minimize the particle size (from 8- to 200-mesh) allowed only minimal increases in the hemicellulose and cellulose conversions after incubation at 37-degrees-C. Apparently, the stover already possesses a large surface area accessible to the enzyme prior to mechanical pretreatment, so that size reduction does little to further increase surface area. Chemical pretreatments with 1 M HCl and 1 M H2SO4 only marginally improved the conversions of hemicellulose and cellulose. However, pretreatment with 1 M NaOH resulted in complete conversion of cellulose for pretreatment times greater than or equal to 3 h. The saccharification of NaOH-pretreated hemicellulose and cellulose in corn stover at various initial corn stover concentrations showed that cellulose saccharification was independent of substrate concentration up to an initial stover concentration of 50 g litre-1. Increases in the enzyme concentration were shown to increase the conversion of cellulose up to an enzyme concentration of 80 units ml-1 (approximately 3000 units (g of stover)-1).