GENOMICS AND PROTEOMICS Secretome analysis of Phanerochaete chrysosporium strain CIRM-BRFM41 grown on softwood Holy Ravalason & Gwénaël Jan & Daniel Mollé & Maryvonne Pasco & Pedro M. Coutinho & Catherine Lapierre & Brigitte Pollet & Frédérique Bertaud & Michel Petit-Conil & Sacha Grisel & Jean-Claude Sigoillot & Marcel Asther & Isabelle Herpoël-Gimbert Received: 27 March 2008 / Revised: 26 June 2008 / Accepted: 26 June 2008 / Published online: 25 July 2008 # Springer-Verlag 2008 Abstract Proteomic analysis was performed to determine and differentiate the composition of the secretomes of Phanerochaete chrysosporium CIRM-BRFM41, a peroxi- dase hypersecretory strain grown under ligninolytic con- ditions and on softwood chips under biopulping conditions. Extracellular proteins from both cultures were analyzed by bidimensional gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrom- etry. A total of 37 spots were identified. The secretome in liquid synthetic medium comprised mainly peroxidases, while several wood-degrading enzymes and enzymes involved in fungal metabolism were detected in biopulping cultures on softwood. This prompted an analysis of the impact of secretome modulation in the presence of softwood chips. Biotreated wood was submitted to kraft cooking and chemical bleaching using chlorine dioxide. The fungal pre-treatment led to a significant increase in pulp yield and a better bleachability of the pulp. This bleachability improvement could be explained by the production of specific lignocellulose-degrading enzymes. Keywords Phanerochaete chrysosporium . Secretome . Softwood . Chemical pulping Appl Microbiol Biotechnol (2008) 80:719–733 DOI 10.1007/s00253-008-1596-x H. Ravalason : S. Grisel : J.-C. Sigoillot : M. Asther : I. Herpoël-Gimbert INRA, UMR1163, Biotechnologie des Champignons Filamenteux, 13000 Marseille, France H. Ravalason : S. Grisel : J.-C. Sigoillot : M. Asther : I. Herpoël-Gimbert Université Aix-Marseille I, UMR1163, BCF, 13000 Marseille, France H. Ravalason : S. Grisel : J.-C. Sigoillot : M. Asther : I. Herpoël-Gimbert Université Aix-Marseille II, UMR1163, BCF, 13000 Marseille, France H. Ravalason (*) : F. Bertaud : M. Petit-Conil Centre Technique du Papier, Domaine Universitaire, B.P. 251, 38044 Grenoble Cedex 9, France e-mail: holy.ravalason@esil.univmed.fr G. Jan : D. Mollé : M. Pasco INRA, UMR1253, Science et Technologie du Lait et de l’Oeuf, 35000 Rennes, France G. Jan : D. Mollé : M. Pasco Agrocampus Rennes, UMR1253, STLO, 35000 Rennes, France P. M. Coutinho CNRS, UMR6098, Architecture et Fonction des Macromolécules Biologiques, 13000 Marseille, France P. M. Coutinho Université Aix-Marseille II, UMR6098, AFMB, 13000 Marseille, France C. Lapierre : B. Pollet INRA, UMR206, Chimie Biologique, 78850 Thierval-Grignon, France C. Lapierre : B. Pollet AgroParisTech, UMR206, Chimie Biologique, 78850 Thierval-Grignon, France