Evaluation of genotoxicity and pro-oxidant effect of the azo dyes: Acids yellow 17, violet 7 and orange 52, and of their degradation products by Pseudomonas putida mt-2

• Published in: Food and chemical toxicology 2007-09, Vol.45 (9), p.1670-1677
• Main Authors: Ben Mansour, Hedi, Corroler, David, Barillier, Daniel, Ghedira, Kamel, Chekir, Leila, Mosrati, Ridha
• Format: Article
• Language: English
• Subjects: amaranth dye; antioxidant activity; antioxidants; azo compounds; Azo Compounds - chemistry; Azo Compounds - metabolism; Azo Compounds - toxicity; Azo dyes; Biodegradation; Biodegradation, Environmental; Biological and medical sciences; Biological Assay; Coloring Agents - chemistry; Coloring Agents - metabolism; Coloring Agents - toxicity; culture media; Escherichia coli; food additives; food coloring; free radical scavengers; free radicals; Genotoxicity; Industrial Microbiology; Kinetics; Life Sciences; Medical sciences; Mutagenicity Tests; Oxidation-Reduction; Pro-oxidant effect; Pseudomonas putida; Pseudomonas putida - metabolism; Pseudomonas putida mt-2; quantitative structure-activity relationships; Toxicology
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/j.fct.2007.02.033

Acids yellow 17, violet 7 and orange 52, very important commercial azo dyes used in the textile, food, paper and cosmetic industries, were degraded by Pseudomonas putida mt-2 at concentrations up to 100 mg/l. The culture media was completely decolorized under static incubation for 60 h, this faster than under continuous shaking incubation. SOS chromotest using Escherichia coli PQ37, with and without metabolic activation (S-9 preparations), was used to assess genotoxicity potential of these dyes before and after biodegradation. None of these dyes or their metabolites was found to be genotoxic in the absence of “Araclor-Induced rat liver microsome” preparations (S-9). However, in presence of the preparation S-9, the genotoxicity of the biodegradation products was highlighted. Metabolites resulting from static cultures were more genotoxic than those obtained in shaken conditions. In addition to genotoxic effects, metabolites have shown a significant ability to induce the formation of superoxide free radical anion ( O 2 - ). The toxicities generated by the pure azo dyes and the pure azo-reduction products (sulfanilic acid, N, N′-dimethyl- p-phenylenediamine and 4′-aminoacetanilid) were compared. These results suggest that P. putida mt-2 degrades the studied azo dyes in two steps: an azo-reduction followed by an oxygen-dependent metabolization. Some of the derived metabolites would be responsible of genotoxicity and metabolic toxicity.