Biofilm mediated decolorization and degradation of reactive red 170 dye by the bacterial consortium isolated from the dyeing industry wastewater sediments.

Reactive dyes are extensively used in a plethora of industries, which in turn release toxic wastes into the environment. The textile dye waste remediation is crucial as it may contain several toxic elements. The utilization of bacterial consortium for bioremediation has acquired consideration, over the utilization of single strains. In this study, a microbial consortium containing three bacterial sp. (Bacillus subtilis, Brevibacillus borstelensis and Bacillus firmus) was tested for its degrading ability of the textile RR 170 dye. The bacterial consortium degraded the dye effectively at lower concentrations and the efficiency decreased as the dye concentration increased. SEM analysis revealed that, with dye treatment, the consortium appeared as tightly packed clumps with rough cell surface and were able to produce EPS and biofilms. EPS production was higher at 40 mg/l, 100 mg/l and 200 mg/l of the dye treatment conditions. Interestingly, the maximum biofilm formation was observed only at 40 µg/ml of the dye treatment, which indicates that RR 170 dye concentration affects the biofilm formation independent of EPS levels. The UV-vis spectroscopy, HPLC, FTIR and 2D-FTIR analyses confirmed the decolorization and biodegradation of RR 170 dye by the bacterial consortium. Toxicological studies performed with the dye and their degraded products in Allium cepa root cells revealed that, whereas the RR 170 dye induced genotoxic stress, the degraded dye products showed no significant genotoxic effects in root cells. Together, the investigated bacterial consortium decolorized and degraded the RR 170 dye resulting in metabolites that are non-toxic to the living cells.

Optimization for enhanced ecofriendly decolorization and detoxification of Reactive Blue160 textile dye by Bacillus subtilis.

The bacterial strain capable of decolorization and detoxification of the Reactive Blue 160 dye was isolated from a dye waste disposal site of Tirupur textile industries. The bacterial strain was screened and selected based on its decolorization capability of RB 160dye, which was identified as Bacillus subtilis by 16S rRNA sequencing. The strain was tested for the decolorization potential under different physio-chemical experimental conditions (pH, temperature, agitation, non-agitation) and observed a complete decolorization at pH 7 and 35 °C under shaking condition within 48 h of time. The enzymes such as, Lignin peroxidase, azoreductase and NADH-DCI were significantly induced in the strain during the decolorization of RB160 dye. Phytotoxicity and microbial toxicity studies revealed that the decolorized product of RB160 dye is less toxic to the plants and microbes. Thus, our results recommend the prospective use of B subtilis in bioremediation of RB160 dye.

Biodegradation of textile dye Reactive Blue 160 by Bacillus firmus (Bacillaceae: Bacillales) and non-target toxicity screening of their degraded products.

The study was envisioned to evaluate the decolorization of Reactive Blue 160 (RB160) dye by using indigenous microbes. Contaminated soil from textile dye industry was collected from Noyyal river basin, Tamil Nadu, India. Potential dye degrading bacterial strain was recognized as Bacillus firmus by 16SrRNA gene sequencing analysis. RB160 dye (500 µg/ml) was effectively degraded by B. firmus and toxicological analyses were performed with RB160 and their degraded product. Phytotoxicity revealed that degraded product of RB160 into non-toxic nature by B. firms. Toxicity assays were carried out on root cells of Allium cepa and human skin cell line (CRL 1474). Toxicity analysis of A. cepa and cell line signifies that dye exerts toxic cause on the root cells and IC50 values of RB160 showed toxic to human skin cell lines, while degradation products of the dye are moderately less in toxic. Zebrafish embryo toxicity also evaluated by RB160 and degraded product on phenotypic deformation, survival, hatching and heartbeat rate. However, RB160 with concentration of 500 µg/ml decrease in the survival, hatching, heartbeat rate and induced phenotypic alterations. In which, degraded products exhibited significant development in zebrafish embryos as compared to dye. Based on the studies effects of RB160 and capability of B. firmus can effectively degrade RB160, and their degraded products were harmless to the environments and aquatic system.