Optimization of Cellulase (E.C. 3.2.1: 4) Production Using Penicillium citrinum MTCC 9620 in Solid State Fermentation

Abstract

Aim: The objective of the present work was to optimize the environmental parameters for Cellulase (1,4 β-endoglucanase, E.C.3.2.1:4) production using Penicillium citrinum MTCC 9620 in Solid State Fermentation. Study Design: One unit of Cellulase (1,4 β-endoglucanase, E.C.3.2.1:4) activity is defined as the amount of enzyme producing 1μmole of glucose equivalent/min measured using UV visible spectrophotometer at 540 nm. Place and Duration of Study: Food Technology laboratory of Dr. S. S. Bhatnagar University Institute of Chemical Engineering & Technology, Panjab University, Chandigarh between January and June 2011. Methodology: Penicillium citrinum MTCC 9620 was maintained on potato dextrose agar (PDA) at 4°C. For Cellulase production Czapek Yeast Extract medium was used as moistening medium. Incubation temperature, pH, incubation time and other parameters like suitable substrate, pre-treatment of the substrate on production of Cellulase in Solid State Fermentation (SSF) was optimized using agricultural residues by Penicillium citrinum MTCC 9620. Microscopic and Spectral properties of substrates were determined to detect the structural changes after pre-treatment. Results: Production of extracellular Cellulase was greatly affected by variation in substrates, pre-treatments of substrate and variation in pH and incubation temperature. Cellulase activity was significantly (p < 0.05) higher when alkali treated wheat bran was used as substrate than untreated substrate. Among three substrates and their three pre-treatment conditions, It has been observed that alkali treated wheat bran was the most suitable substrate for maximum cellulase production (12.56± 0.097U/mL) at pH 5.5 and 30ºC without any extraneous nitrogen source by Penicillium citrinum MTCC 9620 after 120 h of fermentation time. SEM study revealed that during alkali treatment the solid surface become rough which results growth of fungus eventually maximum cellulase production. Conclusion: P. citrinum MTCC 9620 is one of the potential cellulase producing fungal strain. Optimum condition of cellulase (1,4 β-endoglucanase, E.C.3.2.1:4) production by P. citrinum MTCC 9620 was 30°C temperature, 5.5 pH when alkali treated wheat bran was used as substrate. Growth kinetics of P. citrinum MTCC 9620 was studied and it showed adequacy of fit to Monod Model to describe the growth pattern of P. citrinum MTCC 9620 in SSF at 30°C for 120 h incubation period.