Screening and optimization of ligno cellulose degrading fungi using agro wastes as substrates

Abstract

Waste cellulosic materials (potato peel, onion peel, carrot peel and sugar beet peel) are inducers for cellulase, xylanase and ligninase production in wild strains of Penicillium crustosum and Penicillium sp. which were isolated from agro wastes collected from different localities of Bangalore (India). The results obtained indicated that the production of these enzymes started from the fourth to seventh day. The degradation of carboxymethyl cellulose (CMC), and xylan was observed with a yellow opaque layer formation around the colony in case of cellulase enzyme detection, whereas lignin was observed with the formation of brown oxidation zones around the colonies. Among all of fungi studied, Penicillium sp. showed highest clearance zone for 0.67cm whereas, highest clearance zone for xylanase was Penicillium crustosum (0.74 cm). Lignin degradation was observed by Penicillium sp. The brownish black colour was the characteristic feature of positive test and Penicillium crustosum could not degrade lignin. A submerged type of fermentation was carried out for the enzyme production with the substrate concentration of 5.8 % (w/v). The optimization conditions such as incubation time, pH, temperature and effect of different carbon and nitrogen sources were studied. The highest cellulase activity was observed with potato peel as substrate on 6th day and for onion peel, carrot peel and sugar beet peel maximum cellulase activity was on 7th day of incubation. The highest cellulase activity was observed with sugar beet at the pH of 6.5 (1.56 U/ml) and at temperature 20°C (1.28U/ml). With different carbon and nitrogen sources, the highest enzyme activity was observed with urea and onion peel as substrate (2.58U/ml) and with rhamnose and sugar beet peel as substrate (1.49 U/ml).