FEMS Microbiology Reviews 13 (1994) 125-135 © 1994 Federation of European Microbiological Societies 0168-6445/94/$26.00 Published by Elsevier 125 FEMSRE00344 Lignin-modifying enzymes fungi: production and role from selected white-rot in lignin degradation Annele Hatakka * Department of Applied Chemistry and Microbiology, Division of Microbiology, P.O. Box 27, FIN-O0014, University of Helsinki, Finland Abstract: White-rot fungi produce extracellular lignin-modifying enzymes, the best characterized of which are laccase (EC 1.10.3.2), lignin peroxidases (EC 1.11.1.7) and manganese peroxidases (EC 1.11.1.7). Lignin biodegradation studies have been carried out mostly using the white-rot fungus Phanerochaete chrysosporium which produces multiple isoenzymes of lignin peroxidase and manganese peroxidase but does not produce laccase. Many other white-rot fungi produce laccase in addition to lignin and manganese peroxidases and in varying combinations. Based on the enzyme production patterns of an array of white-rot fungi, three categories of fungi are suggested: (i) lignin-manganese peroxidase group (e.g.P. chrysosporium and Phlebia radiata), (ii) manganese peroxidase-laccase group (e.g. Dichomitus squalens and Rigidoporus lignosus), and (iii) lignin peroxidase-laccase group (e.g. Phlebia ochraceofulva and Junghuhnia separabilima). The most efficient lignin degraders, estimated by 14CO~ evolution from 14C-[Ring]-labelled synthetic lignin (DHP), belong to the first group, whereas many of the most selective lignin-degrading fungi belong to the second, although only moderate to good [14CIDHP mineralization is obtained using fungi from this group. The lignin peroxidase-laccase fungi only poorly degrade [14C]DHP. Key words." Lignin; White-rot fungi; Lignin peroxidase; Manganese peroxidase; Laccase; Enzyme regulation Introduction Wood-rotting basidiomyceteous fungi which cause white-rot in wood are the most efficient lignin degraders in nature [1]. Biodegradation of lignin has been studied extensively during the last two decades. In the 1970s the main focus was to define laboratory conditions under which white- rot fungi, and especially Phanerochaete chrysospo- rium Burds., maximally mineralize lignin. In the 1980s, biochemistry of lignin-modifying enzymes * Corresponding author. Tel. +358-0-7085279; Fax. +358-0- 7085212. was predominantly studied, due to the discovery of the enzyme, 'ligninase', thought to be directly involved in lignin biodegradation (references: [1]). In the 1990s, in addition to detailed studies on catalytic and enzymatic properties of lignin-mod- ifying peroxidases and their molecular biology, major lines of research have involved applications of enzymes in biopulping (biomechanical pulping) and pulp bleaching, and a search for the enzymes responsible for lignin degradation in more selec- tive lignin degraders, i.e. fungi which degrade larger amounts of lignin relative to carbohydrates [1,2]. This has led to a reassessment of the biotechnical potential of white-rot fungi other than P. chrysosporium and investigation of their ligninolytic enzyme systems. SSDI 0168-6445(93)E0070-Z Downloaded from https://academic.oup.com/femsre/article/13/2-3/125/549296 by guest on 21 September 2022