Journal of Biotechnology 115 (2005) 333–343 Comparison of different fungal enzymes for bleaching high-quality paper pulps C´ ecile Sigoillot a , Susana Camarero b , Teresa Vidal c , Eric Record a , Mich` ele Asther a , Marta P´ erez-Boada b , Mar´ ıa Jes ´ us Mart´ ınez b , Jean-Claude Sigoillot a , Marcel Asther a , Jos´ e F. Colom c , ´ Angel T. Mart´ ınez b,∗ a UMR 1163 INRA/UP UBCF, CP 925, 163 Avenue Luminy, F-13288 Marseille Cedex 09, France b CIB, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Spain c ETSEIT, UPC, Colom 11, E-08222 Terrassa, Spain Received 23 March 2004; received in revised form 7 September 2004; accepted 14 September 2004 Abstract Wild and recombinant hydrolases and oxidoreductases with a potential interest for environmentally sound bleaching of high- quality paper pulp (from flax) were incorporated into a totally chlorine free (TCF) sequence that also included a peroxide stage. The ability of feruloyl esterase (from Aspergillus niger) and Mn 2+ -oxidizing peroxidases (from Phanerochaete chrysosporium and Pleurotus eryngii) to decrease the final lignin content of flax pulp was shown. Laccase from Pycnoporus cinnabarinus (without mediator) also caused a slight improvement of pulp brightness that was increased in the presence of aryl-alcohol oxidase. However, the best results were obtained when the laccase treatment was performed in the presence of a mediator, 1-hydroxybenzotriazol (HBT), enabling strong delignification of pulps. The enzymatic removal of lignin resulted in high-final brightness values that are difficult to attain by chemical bleaching of this type of pulp. A partial inactivation of laccase by HBT was observed but this negative effect was strongly reduced in the presence of pulp. The good results obtained with the same laccase expressed in A. niger at bioreactor scale, revealed the feasibility of using recombinant laccase for bleaching high-quality non-wood pulps in the presence of a mediator. © 2004 Elsevier B.V. All rights reserved. Keywords: Biobleaching; Paper pulp; Oxidoreductases; Hydrolases; Recombinant enzymes; Flax; Mediator ∗ Corresponding author. Tel.: +34 91 8373112x4407; fax: +34 91 5360432. E-mail address: atmartinez@cib.csic.es ( ´ A.T. Mart´ ınez). 1. Introduction Lignocellulose degradation is a multienzymatic pro- cess due to the complex nature of lignified plant ma- terials (Eriksson et al., 1990). This degradation repre- 0168-1656/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jbiotec.2004.09.006