Production and Optimization of Cellulase from Penicillium sp. Using Corn-cob and Pawpaw Fibre as Substrates

Aim: This study reports the production and optimization of cellulase from Penicillium sp. using corn-cob (CC) and pawpaw fibre (PF) as substrates.

Methods: Nine fungal isolates, obtained from compost soil, were screened for cellulolytic activity. Isolate CPF-1, based on its ability to give the highest zones of clearance and cellulolytic activity, was selected. CPF-1 was identified as Penicillium sp. based on its cultural and morphological characteristics. Cellulase activity was determined by the DNS method on Congo red agar plate. Effects of temperature, pH and metal ions (Zn2+, Hg2+, Fe2+, Mg2+, Ca2+ and Co2+) on crude cellulase activity and stability were studied using two substrates (corn-cob and pawpaw fibre) by solid state fermentation.

Results: Data obtained from the study revealed that the optimal pH and temperature values for the production of crude cellulase by the Penicillium sp. were pH 5 and 30°C, respectively; with maximum cellulase activity of 37.32 IU/mL. Optimum cellulase productivity of 15.787 IU/mL was obtained with CC as the substrate while 2.141 IU/mL was obtained with PF substrate after 1 h of fermentation. The cellulase produced was most stable at pH 5 and temperature of 40°C. Fe2+ and Co2+ were able to stimulate cellulase activity whereas the other ions inhibited the enzyme activity.

Conclusion: This study has revealed the potentials of corn-cob and pawpaw fibre as substrates for cellulase production by Penicillium sp. through solid state fermentation (SSF); with corn-cob as the most suitable substrate. Considering that these substrates are readily available, they present cheaper substrate alternatives for potential large-scale cellulase production.