Synthetic dyes decolorization and bioremediation by indigenous fungi isolated from dye-effluent contaminated environments

Abstract

Biodegradation and detoxification of dyes, Methylene blue (MB), Bromophenol blue (BB), Crystal violet (CV) and Orange G (OG) have been carried out using two fungal isolates Aspergillus niger, and Phanerochaete chrysosporium, isolated from dye contaminated soils. Different approaches were utilized to study biodegradation, viz. agar overlay and broth media means; static and shake conditions at 25°C. Aspergillus niger recorded maximum decolorization of the BB dye under shake/static (68.12 / 71.39 %) followed by MB (60.21 / 75.34 %), CV (49.12 / 53.31 %) and OG (35.23 / 46.16 %). Whereas, P. chrysosporium displayed decolorization under shake/static conditions with MB (73.72 / 86.98 %) followed by BB (70.23 88.24 %), CV (69.56 / 75.62 %) and OG (68.47 / 72.27 %). Under stationary conditions, the fungal isolates performed better, compared to shaking approach. Fungal inoculation raised the pH of the dye solutions to neutral from acidic. Seed germination bioassay showed seed germination, when soaked with bioremediated dye solutions, on the other hand, seeds soaked in non-inoculated dyes, no germination was observed even after five days. Similarly, bacterial growth was also inhibited by uninoculated dyes, which shows their toxic effect against bacteria. The novelty of this work is to assess the biodegradation efficiency of filamentous fungi Aspergillus niger and Phanerochaete chrysosporium for remediation of synthetic dyes, methylene blue, bromophenol blue, crystal violet, and orange G. The results show the viability of these indigenous fungal species as an efficient bioremediation organisms.