Abstract:
Background: The presence of anthraquinone (Disperse blue 64) and azodyes (Acid yellow 17) in a waterbody are considered among the most dangerous pollutants.

Methods: In this study, two different isolated microbes, bacterium and fungus, were individually and as a co-culture applied for the degradation of Disperse Blue 64 (DB 64) and Acid Yellow 17 (AY 17) dyes. The isolates were genetically identified based upon 16S (for bacteria) and ITS/5.8S (for fungus) rRNA genes sequences as Pseudomoans aeruginosa and Aspergillus flavus, respectively.
Results: The fungal/bacterial consortium exhibited a higher percentage of dyes degradation than the individual strains, even at a high concentration of 300 mg/L. Azoreductase could be identified as the main catabolic enzyme and the consortium could induce azoreductase enzyme in the presence of both dyes. However, the specific substrate which achieved the highest azoreductase specific activity was Methyl red (MR) (3.5 U/mg protein). The tentatively proposed metabolites that were detected by HPLC/MS suggested that the reduction process catalyzed the degradation of dyes. The metabolites produced by the action consortium on two dyes were safe on Vicia faba and Triticum vulgaris germination and health of seedlings. Toxicity of the dyes and their degradation products on the plant was different according to the type and chemistry of these compounds as well as the type of irrigated seeds.
Conclusion: We submit that the effective microbial degradation of DB64 and AY17 dyes will lead to safer metabolic products.