Article révisé par les pairs
Résumé : In order to design azo polymers having potential for use as colonic coating materials, the most important factors able to affect the bacterial degradation of azo derivatives were evaluated by a reliable method, using Clostridium perfringens ATCC 3626 as colonic bacteria. The azo degradation was followed by recording the decrease of the absorbance of azo dye solutions in phosphate buffer salt (PBs), pH 7.2, containing Clostridium perfringens, vs time. The results obtained show that the degradation of azo substrates is linear (zero order), faster in basic media and when a redox mediator, such as riboflavin or benzylviologen, is introduced in the incubation medium. Moreover, the substrate redox potential was shown not to affect significantly the degradation rates. However, when several azo dyes are introduced simultaneously into the incubation medium, the microbial azo reduction occurs sequentially as a first. Finally, when Eudragit® RL/RS films containing an azo dye (amaranth) are incubated with Clostridium perfringens or NADPH, the rime required to bleach the films decreases dramatically when the percentage of Eudragit® RL in the films increases, as a result of the increase of the film permeability.