Biotransformation and Detoxification of Xylidine Orange Dye Using Immobilized Cells of Marine-Derived Lysinibacillus sphaericus D3

Abstract

Lysinibacillus sphaericus D3 cell-immobilized beads in natural gel sodium alginate decolorized the xylidine orange dye 1-(dimethylphenylazo)-2-naphthol-6-sulfonic acid sodium salt in the laboratory. Optimal conditions were selected for decolorization and the products formed were evaluated for toxicity by disc diffusion assay against common marine bacteria which revealed the non-toxic nature of the dye-degraded products. Decolorization of the brightly colored dye to colorless products was measured on an Ultra Violet-Vis spectrophotometer and its biodegradation products monitored on Thin Layer Chromatographic plate and High Performance Liquid Chromatography (HPLC). Finally, the metabolites formed in the decolorized medium were characterized by mass spectrometry. This analysis confirms the conversion of the parent molecule into lower molecular weight aromatic phenols and sulfonic acids as the final products of biotransformation. Based on the results, the probable degradation products of xylidine orange were naphthol, naphthylamine-6-sulfonic acid, 2-6-dihydroxynaphthalene, and bis-dinaphthylether. Thus, it may be concluded that the degradation pathway of the dye involved (a) reduction of its azo group by azoreductase enzyme (b) dimerization of the hydrazo compound followed by (c) degradation of monohydrazo as well as dimeric metabolites into low molecular weight aromatics. Finally, it may be worth exploring the possibility of commercially utilizing L. sphaericus D3 for industrial applications for treating large-scale dye waste water.

A genome-scale metabolic reconstruction of Lysinibacillus sphaericus unveils unexploited biotechnological potentials

“…In spite of the growing amount of reports of L . sphaericus strains able to degrade aromatics and other xenobiotics [ 64 – 67 ], there are no detailed studies that aim to elucidate the molecular mechanisms underlying this functional feature.…”

Applications of Marine-Derived Microorganisms and Their Enzymes in Biocatalysis and Biotransformation, the Underexplored Potentials

“…MW-1 (Arora and Jain, 2012). (C) Decolorization of xylidine orange dye by L. sphaericus D3 (Devi et al, 2017). (D) Biotransformation of salicylic acid by Moraxella spp.…”

“…2MPII for PAHs biodegradation, the substrate biotransformation was measured by substrate disappearance and by oxygen uptake in sole carbon experiments, characterizing the reported results as a biodegradation study that indirectly determined the degree of mineralization (Nadalig et al, 2002). Whereas the consumption of xylidine orange dye was determined by decolorization and confirmed by the presence of the identified metabolites (Devi et al, 2017).…”

“…This biocatalyst was immobilized in sodium alginate beads for decolorization of the xylidine orange dye 1-(dimethylphenylazo)-2-naphthol-6-sulfonic acid sodium salt (Figure 3C). A decolorization of 100% was observed, and the metabolites naphthol, 1-naphthylamine-6-sulfonic acid, 2-6-dihydroxynaphthalene, and a dye dimer were identified (Devi et al, 2017).…”

Corncob as an effective, eco-friendly, and economic biosorbent for removing the azo dye Direct Yellow 27 from aqueous solutions

“…For example, even a very small amount of dye (less than 1 mg L -1 ) can markedly color the water, making it unfit for human consumption [ 6 , 7 ]. Such colored water also has reduced sunlight penetration, which lowers photosynthetic activities in the water and increases the heterotrophic activity that depletes dissolved oxygen [ 8 ]. Furthermore, dyes may also cause eutrophication; prevent re-oxygenation of water bodies; pollute ground water; and be toxic to aquatic plants, microorganisms, fish, and mammals [ 9 ].…”