| Large quantities of solid casing waste are being produced by the meat industry and are disposed of in landfills. In this study, the casing waste was utilized for the production of glucose and cellulase enzymes. Six commercial cellulase enzymes were evaluated to determine their hydrolytic performance in converting the waste into glucose with a reaction time of 24 hours at 50°C and 100 rpm. The spent casing waste was also used as a sole carbon source to induce the production of cellulase enzymes in a submerged batch fermentation with Trichoderma reesei RUT-C30. The cellulase production experiments were conducted in 250-mL baffled flasks and in a 2-L bubble-column reactor, both with an incubation temperature of 28°C. The hydrolytic capacity of the commercial and produced cellulase enzymes was evaluated using pure cellulosic paper and spent casing waste. A casing conversion between 80% and 90% in 24 hours was obtained with a casing loading of 25 and 50 g/L with a commercial enzyme loading above 20 IFPU/g casing. The only sugars produced were glucose, which accounted for more than 90%, and cellobiose. Among the different treatments tested, the variable which most affected enzymatic hydrolysis was temperature, followed by pH, enzyme loading, substrate loading, and mixing. The fungus was able to metabolize the spent casing waste for the production of biomass and cellulase enzyme with a casing loading of 25, 50, and 75 g/L. The cellulase activity in the bench scale bubble column reactor was higher than that obtained in the flask and it reached a maximum of 1.3 IFPU/mL with a casing loading of 50 g/L after 7 days. The cleaned aliquot from the culture containing the produced enzyme was then compared with the commercial enzyme and the results showed that the produced enzyme has identical hydrolytic power as the commercial enzymes, with more than 80% casing conversion with 25 and 50 g/L of casing in 24 hours. The hydrolytic enzyme assay also showed that the produced enzyme has a ratio of cellulase-to-beta-glucosidase similar to that found in the commercial enzymes. |
