Institution: | aMicrobiology Unit (MBLA), Catholic University of Louvain, Croix du Sud 3 boîte 6, B 1348 Louvain-la-Neuve, Belgium bWetlands Engineering SPRL, Rue du Laid Burniat 5, B 1348 Louvain-la-Neuve, Belgium cSchool of Biosciences, Department of Biotechnology, New Cavendish Street 115, London W1W6UW, United Kingdom dLaboratoire de Bioinorganique Structurale, CNRS UMR6517, Case 432, Faculté des Sciences St Jérôme, 13397 Marseille Cedex 20, France eDipartimento di Chimica Organica e Biochimica, Università di Napoli “Federico II”, Complesso Universitario Monte S. Angelo, via Cinthia, 80126 Napoli, Italy |
Abstract: | Pycnoporus strains were used as model to understand the role of laccases in the in vivo decolourisation of three anthraquinonic dyes. The decolourisation capability of Pycnoporus sanguineus MUCL 41582 (PS7), which produces laccases as the main oxidative enzyme, was assayed and compared with the decolourisation capability of a control strain, Pycnoporus cinnabarinus MUCL 39533 (PC330) described as laccase-deficient strain. In absence of dye, laccase activity was observed during the trophophase and the idiophase with PS7, while no laccase activity was observed with PC330. Acid Blue 62 (ABu62), Acid Blue 281 (ABu281) and Reactive Blue 19 (RBu19) caused an increase in laccase activity and surprisingly laccase activity was detected with PC330. In vitro, oxidation of all three anthraquinones by a laccase preparation was obtained to a lesser extent than the whole cell process; suggesting that other factor(s) could be required for a complete decolourisation. As the time space of laccase production in the tested fungi was not perfectly coincidental with the decolourisation process, the activity of cellobiose dehydrogenase (CDH) was monitored. Present early in the broth during the growth of the fungi, CDH displayed in vitro a synergism with laccases in the decolourisation of ABu62, and an antagonism with laccases in the decolourisation of ABu281 and RBu19. |