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.