Different elephant grass (Pennisetum purpureum) accessions as substrates for enzyme production for the hydrolysis of lignocellulosic materials

Pennisetum purpureum (elephant grass) is a tropical species presenting C4 metabolism and high productivity, yielding approximately 45 t of dry matter/ha/year. Such productivity makes elephant grass an interesting biomass source to produce second-generation ethanol. However, the high cost of enzymes for enzymatic hydrolysis is one bottleneck on the way to making the production of this biofuel economically viable. The production of cellulases and xylanases by Penicillium echinulatum 9A02S1 was evaluated using 85 different non-treated elephant grass accessions in submerged culture, aiming to identify genotypes with potential biomass for the production of enzymes for the second-generation ethanol industry. The data clearly indicate that it is possible to replace cellulose with elephant grass biomass for the production of cellulases, β-glucosidases and xylanases. The accession IJ 7127 produced 4.7 times more than cellulose for endoglucanases and 4 times for Filter Paper Activity. Ten accessions (BAGCE 69, Napierzinho, IJ 7125, IJ 7126, IJ 7127, IJ 7136, IJ 7141, CAC-262, Ibitinema, 13 AD) produced at least 4 times more β-glucosidases than cellulose, and for xylanases, three accessions (Mercker 86 México, Taiwan A-144, Napier S.E.A.) produced twice as much as the control. The data also indicate that there is no direct relationship between the amount of lignin and cellulose in the substrate, but the mineral salts present in the sample significantly influenced the enzyme production.