Enzyme production and chemical alterations of Eucalyptus grandis wood during biodegradation by Ceriporiopsis subvermispora in cultures supplemented with Mn2+, corn steep liquor and glucose

Eucalyptus grandis biodegradation by Ceriporiopsis subvermispora in solid-state cultures supplemented with corn steep liquor (CSL), glucose and Mn2+ was evaluated. Chemical composition of biotreated wood was determined to correlate the extent of wood transformation with the levels of extracellular agents produced during fungal growth. Manganese-dependent peroxidases and xylanases were detected under all culture conditions. The lowest and the highest MnP activities were observed in cultures supplemented with Mn2+ and CSL/glucose (178 and 1317 IU kg−1 of dry wood, respectively). In all cultures, glucan and xylan losses were lower than 3% while lignin loss varied from 2.7% to 9%. Lignin loss was correlated with the cleavage of aryl-ether linkages detected with basis on derivatization followed by reductive cleavage (DFRC) analysis. The highest lignin loss and the lowest yield of DFRC monomers were observed in cultures supplemented with Mn2+ and CSL. This culture condition presented intermediate levels of MnP production. Oxalate production was not strongly affected by addition of culture supplements suggesting that oxalate was not a limiting agent during wood degradation by C. subvermispora. Conversely, the results suggest that a compromise between the levels of MnP and Mn2+ was necessary to promote intense degradation of lignin revealed by DFRC analysis and lignin mass balances.