The azo dye orange II is used extensively in the textile sector for coloring fabrics. High concentrations of it are released into aqueous environments through textile effluents. Therefore, its removal from textile wastewater and effluents is necessary. Herein, initially, we tested 11 bacterial strains for their capabilities in the degradation of orange II dye. It was revealed in the preliminary data that B. subtilis can more potently degrade the selected dye, which was thus used in the subsequent experiments. To achieve maximum decolorization, the experimental conditions were optimized whereby maximum degradation was achieved at: a 25 ppm dye concentration, pH 7, a temperature of 35 °C, a 1000 mg/L concentration of glucose, a 1000 mg/L urea concentration, a 666.66 mg/L NaCl concentration, an incubation period of 3 days, and with hydroquinone as a redox mediator at a concentration of 66.66 mg/L. The effects of the interaction of the operational factors were further confirmed using response surface methodology, which revealed that at optimum conditions of pH 6.45, a dye concentration of 17.07 mg/L, and an incubation time of 9.96 h at 45.38 °C, the maximum degradation of orange II can be obtained at a desirability coefficient of 1, estimated using the central composite design (CCD). To understand the underlying principles of degradation of the metabolites in the aliquot mixture at the optimized condition, the study steps were extracted and analyzed using GC-MS(Gas Chromatography Mass Spectrometry), FTIR(Fourier Transform Infrared Spectroscopy), 1H and carbon 13 NMR(Nuclear Magnetic Resonance Spectroscopy). The GC-MS pattern revealed that the original dye was degraded into o-xylene and naphthalene. Naphthalene was even obtained in a pure state through silica gel column isolation and confirmed using 1H and 13C NMR spectroscopic analysis. Phytotoxicity tests on Vigna radiata were also conducted and the results confirmed that the dye metabolites were less toxic than the parent dye. These results emphasize that B. subtilis should be used as a potential strain for the bioremediation of textile effluents containing orange II and other toxic azo dyes.
The
Pinus wallichiana, Daphne oleiodes
and
Bidens chinensis
have a long history of being used traditionally for treatment of various types of disorders. Most of the uses have been without any scientific evidence and toxicological assessment. We evaluated the mutagenic and cytotoxic capabilities of various parts of
P. wallichiana
,
D. oleoides
and
B. chinensis
. Ames
Salmonella
mutagenicity assay determined the mutagenicity activity against TA 98 and TA 100 bacterial strains of
Salmonella typhimurium
without metabolic activator S9 system. The number of mutant colonies in negative control was considered as limit to determine the mutagenicity effects of every extract. Brine shrimps lethality bioassay was used to determine the cytotoxic capabilities of the selected plants. The
P. wallichiana, D. oleiodes
and
B. chinensis
did not showed any mutagenic activity both for frameshift mutation (TA98) and base-pair substitution (TA100) without S9 mixture. The crude methanolic extract of
P. wallichiana
stem showed moderate cytotoxicity (53.33%) at 1000 μg/ml with LD
50
value 599.634
.
The
D. oleoides
fruit showed a toxicity of 60% at 1000 μg/ml with LD
50
value 367.730. The
B. chinensis
(whole plant) showed lethality of 63.3% at 1000 μg/ml, with LD
50
204.833. The absence of any mutagenic activity of crude extract of the tested plants in both bacteria strains, TA 98 and TA 100 without the S9 mix confirms the safety of these plants to the consumers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.