Evaluation of Aeromonas Spp. In Microbial Degradation and Decolorization of Reactive Black in Microaerophilic – Aerobic Condition

Abstract

Azo dyes are a widespread class of poorly biodegradable industrial pollutants. In anaerobic environments, azo bonds are reductively cleaved yielding carcinogenic aromatic amines, many of which are assumed to resist further metabolism by anaerobes bacteria. The latter compounds generally require aerobic conditions for their degradation. Reactive Black was found to be degraded using Aeromonas spp. to α-ketoglutaric acid with transient accumulation of 4-aminobenzenesulphonic acid (sulphanilic acid), 4-amino, 3-hydronapthalenesulphonic acid and 4-amino, 5-hydronapthalene 2,7 disulphonic acid as a degradation intermediate in anaerobic facultative batch culture. Colour and Total Organic Carbon (TOC) was successfully removed more than 95% and up to 50% respectively. There is no significant correlation between pH and oxygen depletion since there is slightly change in pH was observed (pH from 7.21 to 7.25) though the anaerobiosis was found developed throughout the experiment (redox potential from 0.7 to 1.6 mV). The anaerobic metabolism of glucose as co-metabolite also shown to provide the electrons required for the initial reductive cleavage of the azo group. This finding suggest that it is possible to mineralize the azo dye in the environment; thereby, avoiding accumulation of toxic intermediates in the water. The results provide evidence that the successive microaerophilic/aerobic stages, using Aeromonas spp. in the same bioreactor, were able to form aromatic amines by the reductive break down of the azo bond and to oxidize them into non-toxic metabolites. Journal of Bior emediation & Biodegradation

Decolorization of azo dye methyl red by suspended and co-immobilized bacterial cells with mediators anthraquinone-2,6-disulfonate and Fe3O4 nanoparticles

“…It has been reported that Aeromonas sp. could degrade azo dyes under either anaerobic or aerobic conditions (Du et al, 2015;Idaka et al, 2008;Shah, 2014). However, A. jandaei strain SCS5 could decolorize and degrade MR under both anaerobic and aerobic conditions suggesting that A. jandaei strain SCS5 would have high potential in the removal of azo dye MR.…”

In Silico Analysis of Bacterial Systems For Textile Azo Dye Decolorization and Affirmation With Wetlab Studies

“…As oxygen inhibits the azoreduction activity, oxygen depletion in microaerophilic cultures allows dissimilatory reduction of azo dyes by facultative anaerobic bacteria. In this study, A. hydrophila with its ability to survive in both aerobic and microaerophilic environments has been used as an efficient single microorganism for non‐specific degradation of textile azo dyes by a microbial respiratory mechanism which may be linked to the electron transport chain for microbial growth . A mechanistic pathway has been proposed for degradation of the chosen azo dye Reactive Yellow F3R by A. hydrophila SK 16.…”

Degradation of Azo Dyes: Bacterial Potential for Bioremediation

“…One of the major problems faced in the degradation of azo dyes in anaerobic environments is the formation of toxic products, notably mutagenic and/or carcinogenic aromatic amines (e.g., benzidine and 4-biphenylamine) that are only degraded in aerobic environments [7,59]. The work of Shah [59] evaluated the degradation of the dye Reactive Black using a strain of Aeromonas sp.…”

“…One of the major problems faced in the degradation of azo dyes in anaerobic environments is the formation of toxic products, notably mutagenic and/or carcinogenic aromatic amines (e.g., benzidine and 4-biphenylamine) that are only degraded in aerobic environments [7,59]. The work of Shah [59] evaluated the degradation of the dye Reactive Black using a strain of Aeromonas sp. in a microaerophilic environment until the color was no longer noticeable in the medium and then promoted the aeration of it to stimulate the oxidation of the aromatic amines-formed by the breakdown of the dye into non-toxic products, obtaining a discolored medium with a low degree of toxicity.…”