Screening of cellulose- and lignin-degrading fungi for improving nutritive quality of ruminant feed

Abstract

This experiment aimed to screen some cellulose- and lignin-degrading fungal species for improving nutritive quality of ruminant feed. Fungal species used were Ganoderma lucidum, Pleurotus ostreatus, Phanerochaete chrysosporium, and Trametes visicolor. These fungal species were grown on Potato Dextrose Broth (PDB) medium that added with 0.5 g substrate, i.e. either rice straw, rice bran or carboxymethyl cellulose for 12 days at room temperature. Harvesting was performed in order to separate fungal mycelium and supernatant that contained crude cellulase enzyme. Among the fungi observed, Ganoderma lucidum had the highest cellulase activity, i.e. 4.02 U/mg. Cellulase activities of Pleurotus ostreatus, Phanerochaete chrysosporium, and Trametes visicolor were 1.53, 1.08, and 0.13 U/mg, respectively. Ganoderma lucidum was further investigated for its ligninolytic enzyme activity, i.e. laccase and manganese peroxidase. It was observed that the fungi had laccase and manganese peroxidase activities of 368.95 and 33.89 U/mL, respectively. Crude enzymes of Ganoderma lucidum that contain cellulase, laccase and manganese peroxidase were further used to increase nutritive quality of rice straw and subjected to in vitro incubation with rumen fluid of cattle.