CONICET | Buscador de Institutos y Recursos Humanos

Abstract Five different strains of white-rot fungi have been tested for their ability todecolorize black liquor on plates and on solid-state fermentation using vermiculite as thesolid inert support. Since the high salt concentration inhibited the growth of all fungi, theblack liquor was dialyzed against distilled water prior to use. A preliminary step on plateswas carried out to qualitatively determine the capacity of the fungal strains for black liquordecolorization. Out of the five fungi studied, Phanerochaete sordida, Pycnoporussanguineus, and Trametes elegans exhibited the more conspicuous decolorization halos inmalt extract medium, while the decolorization by all the strains was not evident when adefined culture medium was used. Cultures on solid-state fermentation using vermiculite assolid support were also tested, the liquid phase was malt extract or glucose-based mediumand supplemented with different black liquor concentrations. Decolorization of black liquorwas largely affected by the fungal strain, the concentration of black liquor, and the carbonsource. The percentage of color removal ranged from 6.14% to 91.86% depending on thefungal strain and culture conditions. Maximal decolorization was observed in malt extractcultures after 60 cultivation days. Interestingly, decolorization in malt extract mediumincreased with increasing black liquor concentration. The highest decolorization value wasachieved by Steccherinum sp. which reduced up to 91.86% the color of the black liquor inmalt extract medium; this percentage is equivalent to 5.2 g L−1 of decolorized black liquor,the highest value reported to date. Traditional technologies used for the treatment of blackliquor are not always effective and may not to be an environmentally friendly process.Vermiculitewhite-rot fungi systems are presented in this work as a promising efficientalternative for the treatment of black liquor.