Inhibition of cellulose saccharification and glycolignin-attacking enzymes of five lignocellulose-degrading fungi by ferulic acid

At 5 g/l, ferulic acid, a plant cell-wall phenolic, severely repressed growth of the lignocellulose-degrading fungi Trichoderma harzianum, Chaetomium celloulolyticum, Phanaerochaete chrysosporium, Trametes versicolor and Pleurotus sajor-caju. At 0.5 g/l, however, it slightly stimulated growth of the latter two organisms, Two classes of extracellular enzymes involved in cellulose and glycolignin breakdown were assayed: cellulases; and phenol oxidases as laccases. All of the strains depolymerized cellulose but two (T. versicolor and P. sajor-caju) also secreted laccases. Laccase-secreting fungal species had normal levels of cellulose saccharification except in the presence of 5 g ferulic acid/l, whereas saccharification by the other strains was suppressed at all concentrations of the phenolic tested.