Isolation, characterization and screening of Pleurotus species for cellulase enzyme production

The increasing need for sustainable methods of lignocellulosic waste degradation has driven interest in the enzymatic capabilities of fungi, particularly members of the genus Pleurotus. This study aimed to isolate, characterize, and screen Pleurotus species from agro-waste-rich soil for their potential cellulase enzyme production. Ten soil samples were separately collected with sterile containers from different locations from an agro-waste dump site having decaying plant organic matter within a mushroom farm at Ugbene 2, Abakpa-Nike, in Enugu state. The samples were serially diluted before being cultured on potato dextrose agar (PDA) using spread plate technique. After incubation at 37°C for 72 hours, fungal colonies were sub-cultured and characterized both macroscopically, microscopically and molecularly. Cellulase activity screening was carried out using a qualitative assay on carboxymethyl cellulose (CMC) agar stained with Congo red, followed by destaining with NaCl. Enzyme activity was indicated by clear halos around fungal colonies. Molecular identification using Internal Transcribed Spacer (ITS) region amplification confirmed the isolates as Pleurotus ostreatus strain 24, Pleurotus ostreatus strain ICMP 11679, Pleurotus ostreatus isolate ITCC3226, and Pleurotus pulmonarius strain DMRP-32. The cellulolytic potential of these strains depicted by the zones of hydrolysis ranged from 14 mm (P. ostreatus strain 24 and ICMP 11679) to 16 mm (P. ostreatus strain ITCC3226 and P. pulmonarius DMRP-32), indicating significant cellulase activity. These findings suggest that the isolated Pleurotus strains are promising candidates for biotechnological applications in biodegradation and biofuel production.