Cellulase Production by Penicillium citrinum using Brewer’s Spent Grain and Pineapple Peels as Cheap, Alternate Substrates

Abstract

Cellulases are major group of enzymes with wide-ranging industrial and biotechnological applications. The high cost of cellulase production is a major factor limiting its industrial applications in cellulose bioconversions, hence the need to develop low-cost production systems for this enzyme. Cellulose-rich plant biomass which may be agricultural or industrial in origin exists abundantly as organic wastes which are detrimental to the environment. This study evaluated cellulase production by Penicillium citrinum isolated from deteriorating orange fruits, using brewer’s spent grain and pineapple peels as cheap, alternate substrates. Cellulase titres 3.82 ± 0.136 U/mL and 1.405 ± 0.151 U/mL were produced by the fungus, using pineapple peels and brewer’s spent grain as substrates, respectively, under submerged fermentation. Maximum cellulase production by P. citrinum occurred with the use of pineapple peels as substrate, after 72 h fermentation period, with the use of pineapple peels at a concentration of 1.5%w/v and peptone as the best nitrogen source. The optima pH and temperature for the production of cellulase by the fungus was found to be 6.0 and 50 oC, respectively. Findings from this study indicated the potential use of pineapple peels as cheaper, alternative substrate for the production of cellulase thus mitigating its hazardous effect on the environment as pollutant. P. citrinum was able to grow and produce good levels of cellulase using solely pineapple peels as low-cost substrate, at high temperature of 50 oC, making this strain and this low-cost agro-industrial residue worthy of further investigation and potentially feasible for a wide range of biotechnological applications.