Statistical optimization of Congo red biodegradation by a bacterial strain of Alcaligenes faecalis

Abstract

The textile industry consumes a significant amount of water and chemicals, with a primary visible chemical pollutant being a dye that poses dangers to humans and aquatic life. In order to tackle this issue, bacterial isolates from textile effluent were screened to assess their ability to degrade Congo red (CR) dye. The decolorization process was optimized using response surface methodology (RSM) based on the Box-Behnken design (BBD). The RSM response optimizer prediction revealed the remarkable efficiency of Alcaligenes faecalis H77 (accession number OK353795), a bacterial strain identified through 16S rRNA sequencing, in decolorizing CR dye. The analysis showed an impressive decolorization rate of 92.51 % for a concentration of 25 mg/L during 72 h, at pH 6.7 and 35 °C. The degradation of the dye was confirmed through liquid mass chromatography-mass spectra analysis, which also indicated the production of less toxic byproducts during the biodegradation process, as identified by LC/MS analysis. In conclusion, Alcaligenes faecalis H77 proved to be highly effective in biodegrading CR, and the statistical modeling employed successfully maximized the efficiency of the biodegradation process.