Decolorization of Synthetic Dyes by Aspergillus flavus Strain EF-3 Isolated from Textile Dyeing Sludge

Abstract

Treatment of textile and dyeing wastewater using indigenous dye-degrading microorganisms is considered to be a sustainable bioremediation strategy. In the present study, a dye-decolorizing fungal strain was isolated from dyeing sludge and identified as Aspergillus flavus strain EF-3 on the basis of cultural, morphological and internal transcribed spacer (ITS) region sequencing. The fungal strain was tested to decolorize five commercially available textile reactive dyes and dye mixture as well. The decolorization efficiencies were ranged from 62% to 100% for 100 mg/L concentration of each dye in Czapek Dox broth within 6 days of incubation at 27°C, and 120 rpm batch-culture conditions. The dyes Novacron Brilliant Blue FN-R, Bezema Yellow S8-G and dye mixture were completely decolorized within the stipulated time period. The nature of decolorization was found to be co-metabolic, i.e., dyes were not used as the sole source of energy for fungal growth and required an external co-substrate, sucrose for induction of decolorization process. The dye removal mechanism involves initial biosorption of the dye in fungal mycelium followed by subsequent biodegradation to colorless end-product. The findings of the present study provide valuable insights to desgin effective biological treatment for dyeing wastewater using the fungus Aspergillus flavus.

Bangladesh J Microbiol, Volume 37 Number 1 June 2020, pp 7-13