Decolourisation of model and industrial dyes by mitosporic fungi in different culture conditions

Six mitosporic fungi belonging to five species (Aspergillus flavus var. flavus, Aspergillus ochraceus, Cladosporium cladosporioides, Penicillium glabrum and Penicillium verrucosum) were selected from a screening on 258 fungal strains as the most promising for their ability to remove 2 model dyes in solid conditions. Hence they were tested in liquid conditions for their ability to decolourise 3 model dyes and 9 industrial dyes widely used in the textile industry. The influence of the culture medium, particularly its carbon:nitrogen ratio, on biomass development and decolourisation capacity was considered. All the strains were able to grow in the dyed media and displayed various degrees of decolourisation according to the dye and culture medium. The decolourisation was due to biosorption phenomena. Aspergillus ochraceus performed the highest decolourisation yield being able to remove all dyes over 90%. This strain was also found very effective, both in the living and inactivated form, against simulated effluents that mimicked the recalcitrance of real wastewaters being composed of ten different dyes at high concentration (1,000 ppm), in saline solution.