Pii: S0043-1354(96)00296-5

-Among 12 basidiomycetaceous fungal strains, Phanerochaete chrysosporium SC26 and K3 and Phanerochaete flavido-alba FPL 106507 were the most efficient in decolorizing paper mill wastes. Enzymatic activities attributable to both families of extracellular ligninases, lignin peroxidase (LIP) and manganese peroxidase (MnP), have been detected in P. flavido-alba FPL 106507. Both peroxidase activities seem to be implicated in the decolorization of partially bio-depurated paper mill waste waters, but LiP activity seems to play a more important role. © 1997 Elsevier Science Ltd. All rights reserved Key words--lignin, Phanerochaete, decolorization, lignin peroxidase, manganese peroxidase INTRODUCTION LiP oxidizes phenolic substrates to phenoxy radicals and catalyzes the oxidative cleavage of The paper and pulp industry discharges brown fl-O-4, Cg-Cfl and other linkages present in lignin colored effluents causing serious environmental and lignin-model compounds (Dodson et al., 1987). problems. The effluents are taken through some type MnP catalyzes the Mn(II) dependent oxidation of of biological treatment, removing biological oxygen lignin model compounds, simple phenols and amines demand (BOD), some chemical oxygen demand (Pribnow et al., 1989). It has also been demonstrated (COD) and total organic carbon (TOC). However, that MnP oxidizes Mn(II) to Mn(III) and that the the color (associated with COD) is only partially Mn(III) produced, in turn, oxidizes the organic reduced (Eriksson and Kirk, 1985). Currently substrates (Wariishi e ta l . , 1989). employed treatment systems for color removal Both enzymes are produced in P. chrysosporium processes, are extremely expensive. Consequently, and in other white rot fungi during secondary several biological methods dealing with the decolmetabolism in response to nitrogen, carbon or sulfur orization of these wastes have been proposed, starvation (Kirk and Farrell, 1987). Since lignin transformation products are the It has been demonstrated that MnP and LiP are main contributors to the color of these effluents, the able to depolymerize lignin in vitro (Hammel and decolorization with ligninolytic fungi, predominantly Moen, 1991; Wariishi et al., 1991). Several white rot based on Phanerochaete chrysosporium strains (Bergfungi have been found to produce MnP, laccase or bauer and Eggert, 1992; Eaton et al., 1982; Joyce aryl alcohol oxidase, but not LiP under ligninolytic et al., 1984; Livernoche et al., 1983; Yin et al., 1989) conditions, however, the role that individual enzymes and extracellular enzymes (Ferrer et al., 1991; Paice play in lignin biodegradation still remains unclear. and Jurasek, 1984) has been studied. This paper deals with the screening of decolorizing Two classes of extracellular glycosylated heme fungi acting on paper mill effluents, the implication of proteins containing protoporphyrin IX, designated as secondary metabolic products in the decolorization lignin peroxidases (LiPs) (Gold et al., 1984; Tien and process and the P. flavido-alba FPL 106507 LiP and Kirk, 1983) and manganese peroxidases (MnPs) MnP activities. (Paszczynski et al., 1986) and a H202 generating system (Kersten et al., 1985) have been identified, to date, and associated with lignin biodegradation by MATERIALS AND METHODS the basidiomycetous P. chrysosporium and other Organisms white rot fungi. The 12 strains of white rot fungi were kindly provided by the U.S.A. Forest Products Laboratory in Madison (Wisconsin): P. chrysosporium K3, P. chrysosporium SC26: P. flavido-alba FPL 106507; P. magnoliae JHG366; P. *Author to whom all correspondence should be addressed sordida 13; Phlebia tremellosa PRL2845; Ph. ostreasmus [Fax: (34) 58 246235]. 0KM3563; Ph. brevispora HHBT030; Phellinus pini FPL