Bioremediation of textile dye solutions, textile dye mixtures and textile effluents by laccase from Aureobasidium pullulans (de Bary) G. Arnaud (1918) (Fungi: Ascomycota)

Abstract

The environmental impact of textile waste water is detrimental to all living species in such habitat and hence there is the need to seek novel bioremediation alternative means to alleviate the effect of these dyes on aquatic life. This study investigated the potentials of Aureobasidium pullulans (de Bary) G. Arnaud (1918) (Fungi: Ascomycota) in bioremediation of waste water through its production of laccase. Both the fungi and its secreted laccase (crude and purified) were used to decolorize textile dyes, textile dye mixtures and textile waste-water effluent. A. pullulans laccase was able to decolorize malachite green (79.9%), allura red (57.5%), tartrazine (21.5%) and methylene blue (4.5%) after 2 h of incubation. The crude A. pullulans laccase was able to decolorize the textile waste water up to 35% after 3 h incubation and it was able to decolorize the blue + green + red dye mixtures more specifically. The purified laccase was able to specifically decolorize malachite green. The fungi was able to absorb the textile dyes when it was inoculated into a laccase culture medium containing the dyes or textile waste water effluent. There was approximately 91% decolorization of malachite green, 71% decolorization of allura red, 23% methylene blue and 38% tartazine after three day incubation A. pullulans when inoculated into the textile water effluent was able to decolorize the textile waste water effluent up to 80% after 5 days of incubation. Manganese peroxidase played additional role in the decolorization as it was detected in the crude filtrate (1.2 units/mL/min) but no lignin peroxidase activity was detected. It can be deduced that A. pullulans is a potential fungi useful for bioremediation of textile waste-water polluted environment.