Production of Cellulase by Trichoderma viride via Submerged Fermentation using Corncob as Substrate

Cellulolytic enzymes are commonly used in lignocellulosic biomass conversion, textile, and paper and pulp industries. However, the high cost of cellulase and the high demand has led to increase researches to explore agro-residues for cost-effective production. This study was aimed at isolating Trichoderma viride from decaying wood and soil, and testing the isolates for cellulase production via submerged fermentation using corncob as substrate. Twenty-one (21) soil samples were collected from three different locations (botanical garden, refuse dump site and decaying wood) and used in the study. Colonies suspected to be Trichoderma viride were identified by microscopy of lactophenol cotton blue-stained preparation and slide culture technique, respectively. Isolates confirmed to be Trichoderma viride were then screened for cellulase production on a mineral salt medium containing carboxymethyl cellulose as an inducer. The isolates were further tested for cellulase production using corncob as the substrate via submerged fermentation. Out of the 21 samples analysed, 4 (19%) were positive for Trichoderma viride based on cultural and microscopic characteristics. The highest occurrence of Trichoderma viride (57%) was recorded from decaying wood samples, while no occurrence (0%) was observed from the botanical garden and refuse dumpsite soils. All four isolates obtained produced cellulase, with T. viride DW6 having the highest zone of cellulose hydrolysis (61.5 ± 2.12 mm) and T. viride DW1 having the least (58.5 ± 2.12 mm). The highest enzyme activity was recorded from T. viride DW4 (3.41 ± 0.46 U/ml) and the lowest from T. viride DW1 (1.77 ± 0.52 U/ml) using corncob as substrate. Trichoderma viride is abundantly present in decaying wood, and such isolates have high cellulase-producing ability, as wood material is rich in cellulose. This preliminary study provides information on the isolation of T. viride from decaying wood and their potential for cellulase production using corncob as substrate.