Degradation of Drimarene Red, a reactive textile dye by an extremophilic Bacillus sp. isolated from fresh water
Publication Date : 22/03/2016
Azo dyes are known for their application in textile dyeing by virtue of their wide range of colours. During the dyeing process, almost 30% of the dye remains unused and enters the effluent stream. Presence of Glauber’s salt (sodium sulphate) or sodium chloride in concentrations 40-100 gl-1 and the highly alkaline (pH 9.8-11.8) nature of the effluent makes conventional treatment (activated sludge process) difficult, as the normal microbial consortium cannot carry out degradation in such conditions. An ideal predominant microorganism, an alkaliphilic and halotolerant bacterium, has been isolated and shown to degrade an azo textile dye (Drimarene Red). The isolate was identified as a species of Bacillus (closely resembling Bacillus beveridgei) and designated Bacillus sp. SG2, based on 16S rDNA sequence analysis. Dye degradation assessed primarily by decolourization efficiency was assessed under different conditions of temperature, initial pH, aeration and sodium chloride concentration. 90% decolourization was seen at ambient temperature under stationary conditions at pH 9.5 and sodium chloride concentration of 5% (w/v) at 24 hours of incubation. UV-Vis absorbance spectra showed that the maximum absorption peaks for the coloured solutions (522 nm and 542 nm) disappeared after 24 hours of incubation. The m/z values of the peaks obtained after HPLC-MS analysis of the uninoculated broth control (344.05 and 655.28) and the decolourized samples (226.95) indicate that the decolourization can be attributed to biodegradation of the dye.
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