Effect of nitrogen source on lignocellulolytic enzyme production by white-rot basidiomycetes under solid-state cultivation Eva Kachlishvili 1 , Michel J. Penninckx 2, *, Nino Tsiklauri 1 and Vladimir Elisashvili 1 1 Durmishidze Institute of Biochemistry and Biotechnology, Academy of Sciences of Georgia, 10 km Agmashenebeli kheivani, 0159, Tbilisi, Georgia 2 Faculte des Sciences, Laboratoire de Physiologie et Ecologie Microbienne, Universite Libre de Bruxelles, c/o Institut Pasteur, 642 Rue Engeland, B-1180, Brussels, Belgium *Author for correspondence: Tel.: +32-2-3733303, Fax: +32-2-3733309, E-mail: upemulb@resulb.ulb.ac.be Received 21 June 2005; accepted 18 August 2005 Keywords: Cellulase, Funalia trogii, laccase, Lentinus edodes, manganese peroxidase, nitrogen source, Pleurotus dryinus, P. tuberregium, solid-state fermentation, xylanase Summary The effect of additional nitrogen sources on lignocellulolytic enzyme production by four species of white-rot fungi (Funalia trogii IBB 146, Lentinus edodes IBB 363, Pleurotus dryinus IBB 903, and P. tuberregium IBB 624) in solid- state fermentation (SSF) of wheat straw and beech tree leaves was strain- and substrate-dependent. In general, the yields of hydrolytic enzymes and laccase increased by supplementation of medium with an additional nitrogen source. This stimulating effect of additional nitrogen on enzyme accumulation was due to higher biomass pro- duction. Only xylanase specific activity of P. dryinus IBB 903 and laccase specific activity of L. edodes IBB 363 increased significantly (by 66% and 73%, respectively) in SSF of wheat straw by addition of nitrogen source to the control medium. Additional nitrogen (20 mM) repressed manganese peroxidase (MnP) production by all fungi tested. The study of the nitrogen concentration effect revealed that 10 mM peptone concentration was optimal for cellulase and xylanase accumulation by P. dryinus IBB 903. While variation of the peptone concentration did not cause the change in MnP yield, elevated concentrations of this nutrient (20–40 mM) led to a 2–3-fold increase of P. dryinus IBB 903 laccase activity. About 10–20 mM concentration of NH 4 NO 3 was optimal for cellulase and xylanase production by F. trogii IBB 146. However, neither the laccase nor the MnP yield was significantly changed by the additional nitrogen source. Introduction White-rot fungi are the only group of microorganisms capable of the degradation of all the basic wood poly- mers, due to their capability to synthesize the relevant hydrolytic (cellulases and hemicellulases) and oxidative (ligninolytic) extracellular enzymes. These are responsi- ble for the degradation of substrate major components, i.e. cellulose, hemicellulose and lignin into low molecu- lar weight compounds that can be assimilated for fungal nutrition (Kirk & Farrell 1987; Eriksson et al. 1990). The major hydrolytic enzymes are endo-1,4-b-D- glucanase (EC 3.2.1.4), exo-1,4-b-D-glucanase (EC 3.2.1.91), and xylanase (EC 3.2.1.8). The ligninolytic enzyme complexes of white-rot fungi differ significantly in their composition. These fungi secrete one or more of three extracellular enzymes that are essential for - lignin degradation: two glycosylated heme-containing peroxidases, lignin peroxidase (EC 1.11.1.14) and Mn-dependent peroxidase (EC 1.11.1.13), and a copper- containing phenoloxidase, laccase (EC 1.10.3.2). The potential application of ligninolytic enzymes in bio- technology has stimulated the investigation of their production with the purpose of selecting the most promising producers of enzymes (Elisashvili et al. 2001; Mikiashvili et al. 2004; Moldes et al. 2004). The physi- ology of ligninolytic enzymes has been extensively studied using submerged and solid-state fermentation of lignocellulosic substrates (Elisashvili et al. 2001; Baldrian & Gabriel 2003; Kapich et al. 2004; Mikiashvili et al. 2004; Moldes et al. 2004). However, not many com- parative studies are available on ligninolytic enzyme production by white-rot basidiomycetes and especially little attention has been given to the evaluation of the World Journal of Microbiology & Biotechnology (2005) Ó Springer 2005 DOI 10.1007/s11274-005-9046-8