Klebsiella and Enterobacter Isolated from Mangrove Wetland Soils in Thailand and Their Application in Biological Decolorization of Textile Reactive Dyes.
ABSTRACT: Wastewater released from textile and dye-based industries is one of the major concerns for human and aquatic beings. Biological decolorization using ligninolytic bacteria has been considered as an effective and alternative approach for the treatment of dyeing wastewater. This study aimed to assess the isolation, characterization and application of soil bacteria isolated from mangrove wetlands in Thailand. Four active bacteria were genetically identified and designated as Klebsiella pneumoniae strain RY10302, Enterobacter sp. strain RY10402, Enterobacter sp. strain RY11902 and Enterobacter sp. strain RY11903. They were observed for ligninolytic activity and decolorization of nine reactive dyes under experimental conditions. All bacteria exhibited strong decolorization efficiency within 72 h of incubation at 0.01% (w/v) of reactive dyes. The decolorization percentage varied from 20% (C.I. Reactive Red 195 decolorized by K. pneumoniae strain RY10302) to 92% (C.I. Reactive Blue 194 decolorized by Enterobacter sp. strain RY11902) in the case of bacterial monoculture, whereas the decolorization percentage for a mixed culture of four bacteria varied from 58% (C.I. Reactive Blue 19) to 94% (C.I. Reactive Black 1). These findings confer the possibility of using these bacteria for the biological decolorization of dyeing wastewater.
Project description:A multicopper oxidase (IOX) produced by Iodidimonas sp. Q-1 has high catalytic efficiency for iodide (I-) oxidation to form molecular iodine (I2). In this study, the potential capacity of IOX for decolorization of recalcitrant dyes was determined. Although IOX did not decolorize any dyes in the absence of redox mediator, significant decolorization of Orange G, Indigo Carmine, Amido Black, and Remazol Brilliant Blue R (RBBR) was observed in the presence of iodide. Addition of 0.1?mM iodide was sufficient to decolorize a total of 3?mM Indigo Carmine, suggesting that iodide functions as a mediator. Such mediator-like function of iodide was not observed in commercially available fungal laccases. The IOX-iodide decolorization system showed much alkaline pH optima of 5.5-6.5 and stronger salt tolerance than fungal laccases did. In addition, actual wastewater discharged from a dyeing factory could be decolorized more than 50% by the system. Since iodide is naturally occurring, non-toxic, and cheaper than common synthetic mediators, the IOX-iodide system is potentially more advantageous than fungal laccase-mediator systems for decolorization of recalcitrant dyes.
Project description:This study was conducted to elucidate the inherent potential of Bacillus sp. MR-1/2, which was isolated from root zone of maize crop grown on a textile wastewater-irrigated soil. The isolated strain was identified through its ribosomal RNA sequence. Under in vitro conditions, the strain demonstrated its tolerance for high concentrations of various heavy metal ions as determined by minimum inhibitory concentration. Moreover, the strain MR-1/2 exhibited many important phytobeneficial traits such as inorganic P solubilization and 1-aminocyclopropane-1-carboxylate (ACC) deaminase ability even under high metal and salt stress. Results showed that the strain proficiently decolorizes various azo dye compounds, e.g., reactive black-5, reactive red-120, and direct blue-1 and congo red, in broth culture. The bioremediation potential of the strain MR-1/2 was further confirmed by analyzing the retrieved azoreductase gene sequence through bioinformatics tools, whereby a subsequent prediction revealed that the azoreductase enzyme activity was involved in decolorization process. When mung bean seeds were grown in pots under various concentrations of decolorized and non-decolorized azo dye, the Bacillus sp. MR-1/2 not only alleviated the azo dye toxicity, but also increased the plant growth parameters. In conclusion, the strain MR-1/2 efficiently decolorized the azo dyes and helped in mung bean plant growth by alleviating azo dye toxicity.
Project description:Two anthraquinonic dyes, C.I. Acid Blue 225 and C.I. Acid Violet 109, were used as models to explore the feasibility of using the horseradish peroxidase enzyme (HRP) in the practical decolorization of anthraquinonic dyes in wastewater. The influence of process parameters such as enzyme concentration, hydrogen peroxide concentration, temperature, dye concentration, and pH was examined. The pH and temperature activity profiles were similar for decolorization of both dyes. Under the optimal conditions, 94.7% of C.I. Acid Violet 109 from aqueous solution was decolorized (treatment time 15 min, enzyme concentration 0.15 IU/mL, hydrogen peroxide concentration 0.4 mM, dye concentration 30 mg/L, pH 4, and temperature 24°C) and 89.36% of C.I. Acid Blue 225 (32 min, enzyme concentration 0.15 IU/mL, hydrogen peroxide concentration 0.04 mM, dye concentration 30 mg/L, pH 5, and temperature 24°C). The mechanism of both reactions has been proven to follow the two substrate ping-pong mechanism with substrate inhibition, revealing the formation of a nonproductive or dead-end complex between dye and HRP or between H2O2 and the oxidized form of the enzyme. Both chemical oxygen demand and total organic carbon values showed that there was a reduction in toxicity after the enzymatic treatment. This study verifies the viability of use of horseradish peroxidase for the wastewaters treatment of similar anthraquinonic dyes.
Project description:Laccases are multi-copper oxidoreductases with broad biotechnological applications. Here, we report detailed biochemical characterization of purified recombinant laccases originating from Myceliophthora thermophila (MtL) and Trametes trogii (TtL). We identified optimal conditions for decolorization of commercial dyes and textile wastewater samples. We also tested the toxicity of decolorized wastewater samples using human peripheral blood mononuclear cells. MtL and TtL were expressed in Saccharomyces cerevisiae, and secreted enzymes were purified by consecutive hydrophobic and gel chromatography. The molecular masses of TtL (~?65 kDa) and MtL (>?100 kDa) suggested glycosylation of the recombinant enzymes. Deglycosylation of MtL and TtL led to 25% and 10% decreases in activity, respectively. In a thermal stability assay, TtL retained 61% and MtL 86% of the initial activity at 40 °C. While TtL retained roughly 50% activity at 60 °C, MtL lost stability at temperatures higher than 40 °C. MtL and TtL preferred syringaldazine as a substrate, and the catalytic efficiencies for ABTS oxidation were 7.5 times lower than for syringaldazine oxidation. In the presence of the mediator HBT, purified TtL almost completely decolorized dyes within 30 min and substantially decolorized wastewater samples from a textile factory (up to 74%) within 20 h. However, products of TtL-catalyzed decolorization were more toxic than MtL-decolorized products, which were almost completely detoxified.
Project description:In the present study, Alcaligenes aquatilis was found to decolorize 82% Synazol red 6HBN after incubation of 4 days at 37 °C and pH 7. Maximum decolorization was found under static conditions by using saw dust and yeast extract as carbon and nitrogen source. It also showed promising potential to decolorize mixture of multiple dyes at a rate of more than 86% in 5 days. Decolorization of dye had positive influence on the growth of bacterium as growth rate was increased along with decolorization. The cleavage of azo bond was confirmed through TLC, HPLC and GC-MS analysis. The dye metabolites produced during bacterial treatment are linked to various pathways including ATP synthesis process. The absence of peaks of wavelength 1612/cm and 1532/cm in bacterially treated FTIR sample demonstrated the cleavage of azo bond. Microbial growth in decolorized dye wastewater shows that bacterially decolorized wastewater is unharmful for the growth of micro-flora. The high decolorization ability of A. aquatilis 3c to convert toxic azo dyes into useful end products may find potential applications in the environmental biotechnology.
Project description:Malachite green (MG) was decolorized by laccase (LacA) of white-rot fungus Cerrena sp. with strong decolorizing ability. Decolorization conditions were optimized with response surface methodology. A highly significant quadratic model was developed to investigate MG decolorization with LacA, and the maximum MG decolorization ratio of 91.6% was predicted under the conditions of 2.8 U mL(-1) LacA, 109.9 mg L(-1) MG and decolorization for 172.4 min. Kinetic studies revealed the Km and kcat values of LacA toward MG were 781.9 mM and 9.5 s(-1), respectively. UV-visible spectra confirmed degradation of MG, and the degradation mechanism was explored with liquid chromatography-mass spectrometry (LC-MS) analysis. Based on the LC-MS spectra of degradation products, LacA catalyzed MG degradation via two simultaneous pathways. In addition, the phytotoxicity of MG, in terms of inhibition on seed germination and seedling root elongation of Nicotiana tabacum and Lactuca sativa, was reduced after laccase treatment. These results suggest that laccase of Cerrena was effective in decolorizing MG and promising in bioremediation of wastewater in food and aquaculture industries.
Project description:An anaerobic sludge (AS), capable of decolorizing a variety of synthetic dyes, was acclimated and is reported here. The sludge presented a much better dye decolorizing ability than that of different individual strains. A broad spectrum of dyes could be decolorized by the sludge. Continuous decolorization tests showed that the sludge exhibited the ability to decolorize repeated additions of dye. The chemical oxygen demand (COD) removal rate of the dye wastewater reached 52% after 12 h of incubation. Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) profiles revealed that the microbial community changed as a result of varying initial concentrations of dyes. Phylogenetic analysis indicated that microbial populations in the sludge belonged to the phyla Acidobacteria, Firmicutes, Bacteroidetes, Chloroflexi and Proteobacteria. The degradation products of the three types of dye were identified. For azo dyes, the anaerobic sludge converted Methyl Orange to N,N-dimethylbenzene-1,4-diamine and 4-aminobenzenesulfonic acid; for triphenylmethane dyes, after Malachite Green was decolorized, the analyzed products were found to be a mixture of N,N-dimethylbenzenamine, 3-dimethyl-aminophenol and 4-dimethylaminobenzophenone; for anthraquinone dyes, two products (acetophenone and 2-methylbenzoic acid) were observed after Reactive Blue 19 decolorization. Together, these results suggest that the anaerobic sludge has promising potential for use in the treatment of industrial wastewater containing various types of dyes.
Project description:Background:Azo dyes are xenobiotic compounds that have bioaccumulated in the environment due to escalated industrial development. These are hazardous in nature, possessing carcinogenic and mutagenic effects on human beings. Objectives:The perspective of the present study was to isolate and to determine azo dye (Reactive Orange-16) degrading potential of marine actinobacteria isolated from sediment samples of Port Blair, India. Material and Methods:Actinobacteria with dye decolorization potential were isolated from sea sediment samples. The actinobacterial isolate with the highest dye decolorizing percentage was identified with the help of phenotypic, biochemical and molecular studies. The different physico-chemical parameters for dye decolorization were also optimized. The nature of decolorization by the potent isolate was determined with the help of High Performance Liquid chromatography (HPLC) and Fourier Transformed Infrared spectroscopy (FTIR) techniques. Further the toxicity of RO-16 decolorized products was investigated with the help of phytotoxcity assay. Results:Out of six actinobacterial isolates, VITVAMB 1 possessed the most efficient RO-16 decolorization property. It decolorized 85.6% of RO-16 (250 mg L-1) within 24hrs. Isolate VITVAMB 1 was identified to be Nocardiopsis sp. Maximum dye decolorization occurred at pH 8, temperature 35°C, 3% salt concentration and a dye concentration of 50 mg L-1. Conclusions:The nature of decolorization by Nocardiopsis sp. was biodegradation. Additionally, the degraded dye metabolites were found to be less toxic than pure dye. The high decolorization potential of VITVAMB 1 and the low toxicity of its degradation products make it a prospective dye removal system. The marine origin of VITVAMB 1 also makes it an attractive source for novel azo dye reducing enzymes.
Project description: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.
Project description:This study explores production of an efficient bioflocculant; BF-VB2, by strain Bacillus sp. TERI VB2 and proposes its potential application in wastewater treatment. One milligram of BF-VB2 can effectively flocculate 1980.0 mg ± 5.0 mg of kaolin particles leading to 99.0% ± 0.5% enhancement in flocculation activity and 99.6% ± 1.0% reduction in turbidity; in less time. BF-VB2 when applied for treatment of textile dyeing industrial wastewater revealed reduction in dye color (82.78% ± 3.03%), COD (92.54% ± 0.24%), TSS (73.59% ± 0.71%), and chloride ions (81.90% ± 0.716%). The best-fit kinetic model (for both COD removal, and dye decolorization) was pseudo-first order with regression coefficient of 0.98 and 0.95, and rate constant of 4.33 × 10-2 and 1.83 × 102, respectively. Bridging due to presence of surface charges have been proposed as flocculation mechanism. From results obtained during test-tube studies, flocculation in larger volumes (0.01-5.0 L) was also performed to intend taking up BF-VB2 for in situ industrial wastewater treatment. This eco-friendly polysaccharide bioflocculant had longer shelf-life, stability to pH and temperature, cation-independence, and emerged to be more efficient than other flocculants assessed. This study proposed BF-VB2 as a potential natural flocculant candidate for industrial application.