No abstract

In the present study, biotransformation of Remazol Orange 3R (RO3R) was studied using well-known bacterial isolate Pseudomonas aeruginosa strain BCH. The dye was decolorized up to 98 % within 15 min. The induction in the level of various oxidoreductive enzymes viz. laccase, tyrosinase, veratryl alcohol oxidase and DCIP reductase were observed in the cells obtained after decolorization of RO3R, which supports their role in decolorization. The metabolites of RO3R obtained after biodegradation were identified and characterized by various analytical techniques viz, HPLC, FTIR, and GC–MS. The RO3R was transformed to the N-(7 amino 8 hydroxy-napthalen-2yl) actamide (m/z, 198), Acetamide (m/z, 59) and Napthalen-1-ol (m/z, 144).

A systemic approach involving in‐silico and in‐vitro tests were used for the decolorization of five azo dyes, Reactive Yellow F3R, Joyfix Yellow 53R, Remazol Red RR, Drimaren Black CL‐S and Disperse Red F3BS, using Aeromonas hydrophila SK16 and Lysinibacillus sphaericus SK13. Homology models for laccase and azoreductase enzymes from these two bacteria were generated using Accelrys Discovery Studio 3.5 and validated. Docking was performed with LeadIT software for binding energy calculation, and active site residues were identified. Reactive Yellow F3R showed highest binding energy with A. hydrophila, which emulated the decolorization percentage by ultraviolet–visible (UV–vis) spectroscopy. High‐performance LC (HPLC), Fourier transform IR spectroscopy (FTIR), and gas chromatography–mass spectrometry (GCMS) supported biotransformation and biodegradation of Reactive Yellow F3R by A. hydrophila SK16, and a biodegradation pathway was proposed. HPLC analysis of treated sample illustrated peaks at retention time 1.481, 3.165, 3.374, and 3.945 min while the control dye showed peaks at 1.478 and 3.106 min. GCMS analysis showed that (2Z)‐but‐2‐ene, 1,3,5‐triazine, aniline, and naphthalene were formed as end products. The in‐silico outcome was in good agreement with experimental studies. Thus, it can be surmised that in‐silico molecular modeling and docking studies can assist as a preliminary tool for screening of potential bacterial system to be employed in textile dye decolorization and degradation studies.

The aim of the present study was to investigate the textile effluent degrading potential of an isolated bacterial consortium PMB11. The consortium had the capacity to decolourize various textile dyes and textile effluent. Ninetyone percent textile effluent decolourization was observed within 120 hours. The physiochemical characterization of textile effluent indicates reduction in the total hardness (CaCO3), fluorides, chlorides, sulphate, chemical oxygen demand, and biochemical oxygen demand of textile effluent after treatment with consortium PMB11. Induction in the activities of NADHdichlorophenolindophenol reductase, azoreductase, and aminopyrine N-demethylase was observed after decolourization, which indicates involvement of these enzymes in the decolourization and degradation process. The biodegradation of dyes from effluent was confirmed using various analytical techniques, such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy, gas chromatography -mass spectroscopy, and HPLC. A phytotoxicity study was performed to confirm the less toxic nature of the degradation metabolites than the effluent.