ABSTRACT
White-rot fungi (Pleurotus eryngii) are decomposers of lignocellulosic substrates. The relationship between the structure of humified organic matter and P. eryngii growth, is poorly understood. This study aimed to evaluate the relationship between the growth and development of white-rot fungi (P. eryngii) in two structurally different sources of humified organic matter. Fungus growth and development (mycelium diameter, fresh and dry mycelium mass, mycelium density, and biological yield) were evaluated in experiments with the application of humic substances (HS) extracted from vermicompost (VC) and peat. Both HS were characterized by CP/MAS 13C NMR spectroscopy associated with chemometrics analysis. The HS present different structural characteristics, with those extracted from VC having a predominance of functionalized C-aliphatics (carbohydrates), low hydrophobicity, and a 90% proportion of cellulose/hemicellulose carbon in the composition. HS extracted from peat have a predominance of C-aromatics (lignin fragments), higher hydrophobicity, and a proportion of lignin carbon of up to 80%. The results showed that P. eryngii growth is dependent on the C-cellulosic and C-lignin balance. HS extracted from lignin-rich peat regulates the fungus growth at initial times and sometimes inhibits the biological performance. The highly cellulosic HS from VC regulate the fungus growth at later times and its biological performance.