Degradation of wheat straw and oak sawdust by Ganoderma applanatum

Abstract

Ganoderma applanatum is a widely-distributed wood decaying species whose ligninolytic enzyme system has not been sufficiently studied. The aims of the study were to profile its Mn-oxidizing peroxidases and laccases and defining of wheat straw and oak sawdust delignification extents depending on cultivation type. Activities of these enzymes were higher in submerged than in solid-state cultivation. Oak sawdust induced the highest activities of Mn-dependent (5545.5 U L−1) and Mn-independent peroxidases (5810.0 U L−1), and wheat straw stimulated laccase activity (11007.0 U L−1). The isoelectric focusing profiles of enzymes and extent of lignocellulose degradation were affected by plant residue as well as type and period of cultivation. Submerged cultivation induced the synthesis of a higher number of enzyme isoforms and the maximum levels of lignin, hemicellulose and cellulose degradation (40.9%, 32.7% and 27.4%) were reached during this oak sawdust fermentation. However, selectivity in fiber mineralisations was the highest during solid-state fermentation of wheat straw, which is important for possible application in various biotechnological processes that require accessible cellulose, such as production of more digestible feed, paper pulp and bioethanol.