Abstract
Present study focuses on exploitation of agricultural waste wheat bran (WB) as growth medium for degradation of textile azo dye C.I. Reactive Blue 172 (RB 172) using a single bacteriumP. rettgeristrain HSL1 (GenBank accession numberJX853768.1). The bacterium was found to completely decolorize 50 mg L−1of dye RB 172 within 20 h at 30 ± 0.2°C under microaerophilic incubation conditions. Additionally, significant reduction in COD (85%) and TOC (52%) contents of dye decolorized medium was observed which suggested its mineralization. Induction in the activities of azoreductase (159%) and NADH-DCIP reductase (88%) provided an evidence for reductive cleavage of dye RB 172. The HPLC, FTIR, and GC-MS analysis of decolorized products confirmed the degradation of dye into various metabolites. The proposed metabolic pathway for biodegradation of RB 172 has been elucidated which showed the formation of 2 intermediate metabolites, namely, 4-(ethenylsulfonyl) aniline and 1-amino-1-(4-aminophenyl) propan-2-one. The acute and phytotoxicity evaluation of degraded metabolites suggests that bacterial strain favors the detoxification of dye RB 172. Thus, WB could be utilized as a low-cost growth medium for the enrichment of bacteria and their further use for biodegradation of azo dyes and its derivatives containing wastes into nontoxic form.
Highlights
Synthetic textile dyes are of complex aromatic structures specially designed for chemical stability and versatility and to resist the effect of high temperature during wet processing operations which makes them highly recalcitrant [1]
Degradation of textile effluent by a developed bacterial consortium consisting of Providencia sp
As per our best knowledge, this is the first report showing the decolorization of textile azo dye by Providencia sp. using wheat bran (WB) as growth medium under submerged conditions
Summary
Synthetic textile dyes are of complex aromatic structures specially designed for chemical stability and versatility and to resist the effect of high temperature during wet processing operations which makes them highly recalcitrant [1]. Thousands of such synthetic dyes are extensively used in the textile industry for dyeing and printing purposes [2]. The discharge of azo dyes containing wastewaters into the environment may lead to the bioaccumulation which causes toxic effect on aquatic life and even carcinogenic and mutagenic effect on humans because of the conversion of azo group into aromatic amines [5, 6]. Aside from the human toxicity, colour of dyes interrupts the aquatic environment by reducing light penetration, gas solubility, and interference of phytoplankton’s photosynthesis [7]
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