Interspecific Interactions Among White-Rot Fungi Modulate the Production of Extracellular Oxidative Enzymes and Wheat Straw Degradation

Wheat straw contains recalcitrant lignin that limits its bioconversion. This study examined how white-rot fungal cocultivation affects extracellular oxidative enzyme activities and wheat-straw degradation. Nine fungal strains were screened using aniline blue and guaiacol plate assays, and three selected strains—Cerrena unicolor WS4761, Pleurotus ostreatus WS4122, and Trametes versicolor WS4313—were compared in monoculture and pairwise coculture. Coculture enhanced laccase activity, whereas the peroxidase response depended on the fungal pairing. The coculture of C. unicolor WS4761 and P. ostreatus WS4122 showed the highest measured laccase and peroxidase activities. On day 20, its laccase activity was approximately 5 and 62 times, and its peroxidase activity approximately 17 and 5 times, those of the respective monocultures at the same sampling time. The coculture of P. ostreatus WS4122 and T. versicolor WS4313 produced the greatest weight loss (48.09%) and cellulose and hemicellulose losses (54.50% and 64.65%, respectively). However, no coculture exceeded the highest mean lignin loss recorded in the C. unicolor WS4761 monoculture (60.53%), which also showed relatively low cellulose loss (22.82%). Thus, enhanced oxidative enzyme activities did not necessarily improve selective delignification. Greater carbohydrate losses in some cocultures may limit their advantages for pretreatment aimed at preserving cellulose, while the C. unicolor WS4761 monoculture showed potential for balancing lignin removal and cellulose preservation.