Lignocellulolytic activity of Coniophora puteana and Trametes versicolor in fermentation of wheat bran and decay of hydrothermally modified hardwoods

• Wheat bran substrate favors the production of fungal hydrolases and ligninases.
• Hydrothermal modification of hardwoods at 170 °C/1 h is efficient against decay.
• Wood thermal modification improves the decay resistance but does not stop the secretion of lignocellulolytic enzymes.
• Enzymatic activity depends on hardwood species rather than treatment regime.

In submerged- (SF) and solid-state fermentation (SSF) of wheat bran (WB) substrate, the brown-rot fungus Coniophora puteana produced high levels of endoglucanase, xylanase and filter paper activity (FPA) but neither laccase nor manganese-dependent peroxidase (MnP) activity was detected. SF favored the accumulation of endoglucanase (3.2 U ml−1), xylanase (9.4 U ml−1), and FPA (0.14 U ml−1) by C. puteana. Under the same cultivation conditions, the white-rot fungus Trametes versicolor secreted lower levels of hydrolytic enzymes but expressed high laccase and MnP activities in SF (0.93 U ml−1 and 1.75 U ml−1, respectively) and SSF (1.54 U ml−1 and 1.63 U ml−1, respectively) of WB. Extracellular enzymatic activities and weight loss (WL) were investigated in untreated and hydrothermally modified (HTM) birch, aspen, and alder wood blocks, exposed to C. puteana and T. versicolor. Acetone soluble extractives and cellulose content were determined in HTM hardwoods colonized by C. puteana. WL and cellulose degradation in untreated wood correlated with the high levels of cellulase activity produced by C. puteana. HTM noticeably increased decay resistance, although it was not toxic to the fungal growth and did not disturb the secretion of the enzymes involved in wood degradation.