Decolorization of anthraquinone-based dye (Vat Brown R) by Pseudomonas aeruginosa NCH - Optimization and kinetic study

Abstract

The objective of this research work is related to the fact that the source of isolation and acclimatization process influences the microorganism’s potential for the decolorization of various substances. Some of the widely used anthraquinone vat dyes decolorization by the pure bacterial strain is a significant aspect that will assist in the in-situ bioremediation of the ecosystem.The present study is to evaluate the enhanced decolorization of Vat Brown R by an isolated bacterium, Pseudomonas aeruginosa NCH, from textile dye wastewater under aerobic conditions. The effect of pH, temperature, and inoculum size was optimized using response surface methodology with the box-behnken experimental design. The strain NCH showed maximum decolorization efficacy under optimum conditions at pH9.76, temperature 34.69C, and an inoculum size of 9.51% (v/v), respectively. A decolorization of 90.34% was observed with 100 mg L−1of Vat Brown R within 18h under these conditions. Confirmatory experiments have verified the optimum combination of the three variables predicted by RSM. Kinetics study was carried out using various approaches: Michaelis-Menten (Vmax = 29.1 mg L−1 h−1 and Km = 25.2 mg L−1), Lineweaver-Burk (Vmax = 30.12 mg L−1 h−1 and Km = 26.91 mg L−1), and Eadie-hofstee model (Vmax = 30.23 mg L−1h−1and Km = 27.29 mg L−1), and the results showed that the degradation followed a first-order reaction kinetics. The subsequent degradation of the dye and the formation of metabolites were studied using analytical techniques such as UV-vis spectroscopy and FT-IR analysis. UV-vis spectroscopy validated the detoxification of the dye and confirmed that Pseudomonas sp. NCH overcomes this decolorizing activity through biodegradation. This study investigated the highest decolorization efficiency of strain NCHused in the biodegradation of wastewaters containing anthraquinone dyes.