it usually requires anaerobic followed by aerobic conditions. im looking for those papers or answers where degradation and mineralization of the azo dye was done only in anerobic condtions.
You are right Gopi, however, I feel that it is possible are you may try facultative anaerobes like Klebsiella strains which can ? In our study we never used anaerobic but totally aerobic conditions for azo-dye degradation.
Article Biodegradation of hexamethyl-p-rosaniline chloride (crystal ...
Hi, Azoreductase is the most well-studied enzyme in the context of azo dye degradation (symmetrical degradation i.e. cleavage of the azo bond to form amines). The azoreductase mediated extracellular dye degradation is dependent on the availability of redox mediators. The redox mediators get reduced due to azoreductase which in turn gets oxidized due to electronegative N=N bond, reducing the N=N bond in return (means dye decolorization). However, if there is oxygen in the system, the redox mediators get oxidized because of the oxygen rather than N=N bond, so dye remains intact and undecolorized. Thus, oxygen here acts as an inhibitor.
Though dye decolorization is not only limited to anaerobic environment, laccases and peroxidases are also known to degrade dye in many fungi. However, the important question is, WHY NOT MINERALIZATION IN ANAEROBIC CONDITION?
It is because dye decolorization forms aromatic amines (mono or polycyclic) which further require oxygen for complete degradation. As I have mentioned above that dye decolorization is extracellular, happens outside the cell, which means that microbes are not consuming the dye directly as a carbon source, they are first reducing it into simpler forms. However, for carbon utilization from the degraded products, microbes have to consume the dye inside the cell, which requires MONOOXYGENASES and DIOXYGENASES pathways. So, as the name suggests, OXYGEN is required. Usually, monocyclic aromatics are converted into catechol and then enters into TCA cycle for complete mineralization.
So, complete degradation requires two step processes. However, the field is still unexplored in the context of mineralization under anaerobic conditions. Dye degradation is non-specific (as I mentioned in my last publication), as there are many alternate pathways.
I hope it helped
Article Detoxification of azo dyes in the context of environmental processes
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