Influence of the chemical structure on the biodegradability of acids yellow 17, violet 7 and orange 52 byPseudomonas putida

Abstract

In the present study, the textiles azo dyes acids orange 52 (AO52), yellow 17 (AY17) and violet 7 (AV7) were degraded by Pseudomonas putida mt-2 in mineral medium at concentration up to 100 mg/l. The culture media were completely (case of AO52) or partially (case of AY17 and AV7) decolourised under static incubation, this faster than under continuous shaking incubation. Decolourisation kinetic by intact cells indicated that AO52 disappeared completely and faster than the two other azo dyes. To understand the differentiated action of this bacterium on the three dyes, cell-free extracts activity was assessed and compared for each couple of dyes "inductor-substrate". Results showed the same halfsaturation constant Km for a given dye as a substrate whatever the dye inductor, from where the assumption of a same protein with nonspecific azoreductase activity. The enzyme showed slightly more affinity for AO52 than for AY17 and AV7, but especially weaker specific activities against these two last dyes independently of the inductor. Finally, AO52 would be the best azoreductase inductor among the three tested dyes. These results indicated that the level as well the induction as the specificity of the azoreductase activity seems to be strongly dependent on the chemical structure of the dyes.

Immobilization of Laccase on Magnetic Carriers and Its Use in Decolorization of Dyes

“…This could be the reason why Acid Blue 225 was more degraded than the other dyes 39 . Weak degradation rate between diazoic compounds could rarely be imputed to the presence of the sulfonic and chloro substituents 40 . The second highest amount of dye decolorized by free laccase was calculated at dye Direct Blue 78.…”