Fficient Aerobic Degradation of Various Azo Dyes by a Sphingomonas sp Isolated from Petroleum Sludge

Abstract

The extensive discharge of textile dyes in industrial wastewater and the recalcitrant nature of azo dyes have fueled a strong interest in exploring efficient and environmentally friendly approaches for wastewater remediation. In this present study, we report on the isolation and characterization of a Sphingomonas sp. strain from petroleum sludge that was capable of efficiently degrading various classes of dyes. A subsequent detailed analysis using a panel of 12 azo dyes showed that this strain was capable of efficient aerobic degradation of at least 7 diverse azo dyes. Furthermore, these dyes could also be degraded (more than 70% in 24 hours) under static (anaerobic) culture conditions by this Sphingomonas sp. Lastly, HPLC analysis of the metabolites of three different azo dyes showed that depending on the availability of oxygen during the culturing and dye degradation process, and different sets of metabolites could be produced from these dyes. The current study establishes the usefulness of screening petroleum sludge for the isolation of novel bacterial strains for efficient bioremediation and highlights the different degradative pathways that are taken during aerobic and anaerobic bacterial dye degradation processes