Decolorization and degradation of Direct Blue-1 (Azo dye) by newly isolated fungus Aspergillus terreus GS28, from sludge of carpet industry

Abstract

Abstract Decolorization of azo dye is one of the most challenging tasks before releasing the wastewater discharged from azo dye containing effluent. Microbial decolorization of Direct Blue-1 (DB-1) via degradation and adsorption is one of the eco-friendly and feasible way. Therefore, in this study we have isolated native fungal isolate GS28 from sludge of carpet industry, Bhadohi (U.P.), India and optimized its role in decolorization of DB-1 dye. Batch experiment was conducted using potato dextrose broth (PDB) medium at the concentration of DB-1 ranges from 100-1000 mgL−1 and maximum decolorization (98.4%) was recorded at 100 mgL−1, 30 °C within 168h after incubation. Isolate GS28 also exhibited efficient decolorization ability in the pH ranges from 4.0-9.0, temperature (25-40 °C), under the presence of different metal (Mn, Cu, Zn and Fe) and with different carbon sources (PDB+G, PDB+B, PDB+P, PDB+Y). Isolate GS28 was subjected to ITS region gene sequencing and was identified as Aspergillus terreus (Genbank accession number; MK574833). The role of degradation and adsorption in DB-1 decolorization was confirmed by GC–MS, enzymatic activity (laccase and manganese-peroxidase) and FTIR investigation. Increased activity of laccase, manganese-peroxidase was recorded in GS28 in exposure of 100,500 and 1000 mgL−1 of DB-1 at 120 h after incubation while, the level of H 2 O2 and protein content were low as compare to control. The degraded products of DB-1 were characterized by GC–MS as phenol,2,6-bis(1,1-Diemethylethyl), 4,5-Diazotricyclo[4.3.0.0(3,7)non-4-in-2-one] and 1,2-benzene dicarboxylic acid,3-nitro. Toxicity of degraded products was less than DB-1, confirmed by good germination rate and growth of Solanum leucopersicum and Triticum aestivum seeds. Therefore, the isolate GS28 can be utilized for treatment of industrial wastewater containing azo dyes in economic and ecofriendly way.