Microbial degradation of textile dye reactive blue 250 (RB 250) by the novel Pseudomonas aeruginosa RGB11: a sustainable approach.

Untreated textile effluent discharge has increased due to rapid industrialization and human activity, posing a serious and growing threat to environmental well-being over the past few decades. This study isolates a novel bacterial strain, Pseudomonas aeruginosa RGB11, from sewage sludge capable of degrading the azo dye Reactive Blue 250 dye (RB 250) as identified via 16S rRNA gene sequencing. Decolorization of RB 250 was tested in Minimal Salt Media (MSM) throughout the studies. Under static conditions, pH 7, and 37 °C, the dye showed 88.91% decolorization after 24 h, which increased to 96.27% at pH 9 and 93.15% at 45 °C. Adding 1% w/v sucrose and yeast extract as carbon and nitrogen sources increased the decolorization to 96.83% and 97.54%, respectively. A study on growth kinetics over 8 h showed that as the Optical Density (OD) of bacteria increased at 600 nm, the absorbance of the dye decreased at 604 nm, indicating the bacterial role in the decolorization process. FT-IR analysis of the metabolite extracted after decolorization revealed the shift in the intensity of the characteristic peak of the RB 250 dye and the formation of new peaks, which can be attributed to the degradation of dye and generation of intermediates in the decolorized solution. The LC-MS study further confirms degradation as the parental peak in the dye disappeared and smaller new peaks were observed, possibly due to breakage of characteristic bonds in dye like the azo bond. Haemolysis test on blood agar demonstrated gamma haemolysis confirming that the novel strain of Pseudomonas aeruginosa RGB11 doesn't produce haemolysins and is a non-pathogenic strain. Thus, emphasizing the efficiency of Pseudomonas aeruginosa RGB11 as potential candidate for dye decolourizer for textile effluents. It has immense potential to serve as a contributor to environmental studies by providing a means of sustainable bioremediation for textile effluents.