Immobilisation of soybean seed coat peroxidase on its natural support for phenol removal from wastewater

Soybean seed coat peroxidase (SBP; EC 1.11.1.7) was immobilised on its natural support, soybean seed coats, anticipating its use in phenol removal. Periodate and glutaraldehyde chemistries were assayed. Periodate failed to immobilise any SBP, whereas glutaraldehyde was effective. The optimum concentration of glutaraldehyde was found to be 1%. Immobilisation shifted the optimum pH for phenol removal from 4.0 to 6.0. Treated seed coat retained its activity over a 4-week period, and reusability assays showed that treated seed coats could be reused once for phenol removal. Polyethylene glycol (PEG) increased the stability of phenol degradation activity. In addition, the phenolic polymer was adsorbed on to seed coats, thus making removal of the polymeric product easier.     

Immobilisation of soybean seed coat peroxidase on its natural support for phenol removal from wastewater

Soybean seed coat peroxidase (SBP; EC 1.11.1.7) was immobilised on its natural support, soybean seed coats, anticipating its use in phenol removal. Periodate and glutaraldehyde chemistries were assayed. Periodate failed to immobilise any SBP, whereas glutaraldehyde was effective. The optimum concentration of glutaraldehyde was found to be 1%. Immobilisation shifted the optimum pH for phenol removal from 4.0 to 6.0. Treated seed coat retained its activity over a 4-week period, and reusability assays showed that treated seed coats could be reused once for phenol removal. Polyethylene glycol (PEG) increased the stability of phenol degradation activity. In addition, the phenolic polymer was adsorbed on to seed coats, thus making removal of the polymeric product easier.     

Decolorization of azo dye using PVA-immobilized microorganisms

A microbial consortium having a high capacity for rapid decolorization of azo dye (RED RBN) was immobilized by a phosphorylated polyvinyl alcohol (PVA) gel. The immobilized-cell beads exhibited a color removal capability of 75%, even at a high concentration of RED RBN (500 mg l(-1)) within 12 h using flask culture. The continuous operation was conducted at a hydraulic retention time (HRT) of 5-20 h in which the dye loading rate ranged from 240 to 60 mg dye h(-1). A removal efficiency exceeding 90% was obtained at the HRT higher than 10 h. No recognizable destruction of bead appearance was observed in the 6-month operation. Examination of the mechanism of the decolorization process by cell beads indicated that it proceeded primarily by biological decolorization associated with partial adsorption of the dye onto the entrapped cells and gel matrix. Microscopic observation revealed that the microbial consortium contained in the gel beads was at least made up of three kinds of bacterial species. From the economical viewpoint, alternative cheaper nitrogen sources such as fish meal, soybean meal, pharmamedia and vita yeast powder were examined.     

Oxidative degradation of Remazol Turquoise Blue G 133 by soybean peroxidase

Reactive dyes are widely employed in textile industries and their removal from wastewaters is a relevant environmental problem. In addition to chemical and physical methods, several bioremediation approaches, involving intact micro-organisms or isolated enzymes, have been proposed to decolorize dye solutions. In this paper, we report the complete and fast decolourization of a Cu(II)-phthalocyanine based reactive dye (Remazol Turquoise Blue G 133) by means of the soybean peroxidase/H₂O₂ system. The oxidative degradation of the dye in aqueous solution at 25 °C was studied as function of pH, revealing a quantitative decolourization yield at acidic pH values with a maximum of activity at pH 3.3. The reaction products were identified and characterized by HPLC-diode array detector (DAD)-mass spectrometry (MS), ionic chromatography and EPR techniques. This analysis showed that the enzyme catalyses the breaking of the phthalocyanine ring producing sulfophthalimide as the main degradation product, and the release of stoichiometric amount of ammonium and Cu(II) ions.     

Enhanced dye decolorization efficiency by citraconic anhydride-modified horseradish peroxidase

Bromophenol blue and methyl orange removal capabilities of citraconic anhydride-modified horseradish peroxidase were compared with those of native horseradish peroxidase. Citraconic anhydride-modified horseradish peroxidase showed higher decolorization efficiencies for both dyes than native horseradish peroxidase. Upon the chemical modification, the decolorization efficiencies were increased by 1.8% and 12.4% for bromophenol blue and methyl orange, respectively. The quantitative relationships between decolorization efficiencies of dyes and reaction conditions were also investigated. Experimental data revealed that aqueous phase pH, reaction time, temperature, enzyme concentration and ratio of dye and H₂O₂ play a significant role on the dye degradation. Lower dose of citraconic anhydride-modified horseradish peroxidase was required than that of native enzyme for the decolorizations of both dyes to obtain the same decolorization efficiencies. Citraconic anhydride-modified HRP exhibited a good decolorization of dye over a wide range of dye concentration from 8 to 24 or 32 μmol l⁻¹ at 300 μmol l⁻¹ H₂O₂, which would match industrial expectations. Kinetic constants for two different dyes were also determined. Citraconic anhydride-modified horseradish peroxidase shows greater affinity and catalytic efficiency than native horseradish peroxidase for both dyes.     

毛木耳对孔雀石绿染料降解条件的优化

随着我国印染工业的发展,废水对生态环境的危害日趋严重,亟需开发一种脱色明显且成本低廉的降解方法。本研究发现毛木耳Auricularia cornea菌株AC5对不同结构的染料均具有一定的降解作用,尤其是三苯甲烷类染料。利用26℃、160r/min振荡培养7d的粗酶液对染料（75.0mg/L）进行12h降解,结果显示三苯甲烷染料孔雀石绿、结晶紫,蒽醌染料活性蓝19和偶氮染料活性蓝222的降解效率分别为83.27%、71.77%、67.81%和63.92%。染料降解实验和酶活力测定结果表明,毛木耳对孔雀石绿的降解率达到最高时漆酶活性最高,为321.0U/mL,木质素过氧化物酶和锰过氧化物酶活性较低。因此,推测在降解过程中漆酶起到主要作用。研究表明利用毛木耳菌丝发酵液降解染料废水成本低且操作方便,为染料废水的降解研究提供了前期基础。     

Identification of two cytosolic ascorbate peroxidase cDNAs from soybean leaves and characterization of their products by functional expression in E. coli

Screening of a cDNA library from soybean (Glycine max (L.) Merr. cv. Century) with probes based upon cytosolic ascorbate peroxidase (APx; EC 1.11.1.11) genes identified two full-length clones (SOYAPx1, SOYAPx2) apparently encoding for different soybean leaf cytosolic APxs. The deduced amino acid sequences of the two APx cDNA products differed in 13 of the 250 amino acids. The SOYAPx1 cDNA was identical to the cytosolic APx cDNA previously found in soybean root nodules. Escherichia coli expression systems were developed using both soybean APx cDNAs. Recombinant SOYAPx1 and SOYAPx2 were then utilized to characterize the enzymatic properties of the two APx cDNA products. Received: 10 May 1997 / Accepted: 19 June 1997     

Biosorption of reactive dye from textile wastewater by non-viable biomass of Aspergillus niger and Spirogyra sp

The potential of Aspergillus niger fungus and Spirogyra sp., a fresh water green algae, was investigated as a biosorbents for removal of reactive dye (Synazol) from its multi component textile wastewater. The results showed that pre-treatment of fungal and algal biomasses with autoclaving increased the removal of dye than pre-treatment with gamma-irradiation. The effects of operational parameters (pH, temperature, biomass concentration and time) on dye removal were examined. The results obtained revealed that dried autoclaved biomass of A. niger and Spirogyra sp. exhibited maximum dye removal (88% and 85%, respectively) at pH3, temperature 30 degrees C and 8 gl(-1)(w/v) biomass conc. after 18h contact time. The stability and efficiency of both organisms in the long-term repetitive operation were also investigated. The results showed that the non-viable biomasses possessed high stability and efficiency of dye removal over 3 repeated batches.     

Adsorption of methyl violet from aqueous solutions by the biochars derived from crop residues

The adsorption of methyl violet by the biochars from crop residues was investigated with batch and leaching experiments--adsorption capacity varied with their feedstock in the following order: canola straw char>peanut straw char>soybean straw char>rice hull char. This order was generally consistent with the amount of negative charge of the biochars. Zeta potentials and Fourier transform infrared photoacoustic spectroscopy, combined with adsorption isotherms and effect of ionic strength, indicated that adsorption of methyl violet on biochars involved electrostatic attraction, specific interaction between the dye and carboxylate and phenolic hydroxyl groups on the biochars, and surface precipitation. Leaching experiments showed that 156 g of rice hull char almost completely removed methyl violet from 18.2 L of water containing 1.0 mmol/L of methyl violet. The biochars had high removal efficiency for methyl violet and could be effective adsorbents for removal of methyl violet from wastewater.     

Adsorption of dissolved Reactive red dye from aqueous phase onto activated carbon prepared from agricultural waste

The adsorption of Reactive red dye (RR) onto Coconut tree flower carbon (CFC) and Jute fibre carbon (JFC) from aqueous solution was investigated. Adsorption studies were carried out at different initial dye concentrations, initial solution pH and adsorbent doses. The kinetic studies were also conducted; the adsorption of Reactive red onto CFC and JFC followed pseudosecond-order rate equation. The effective diffusion coefficient was evaluated to establish the film diffusion mechanism. Quantitative removal of Reactive red dye was achieved at strongly acidic conditions for both the carbons studied. The adsorption isotherm data were fitted well to Langmuir isotherm and the adsorption capacity were found to be 181.9 and 200 mg/g for CFC and JFC, respectively. The overall rate of dye adsorption appeared to be controlled by chemisorption, in this case in accordance with poor desorption studies.     

Recycle in upflow anaerobic sludge blanket reactor on treatment of real textile dye effluent

The discharge of textile wastewater containing dye in the environment is varying for both toxicology and esthetical reasons as dyes impede light penetration, damage the quality of the receiving streams. Upflow anaerobic sludge blanket reactor with anaerobic digester sludge treating starch wastewater has been used to investigate the removal efficiency of chemical oxygen demand (COD) and colour of textile dye wastewater. In this study, the starch and textile dye wastewater was mixed at 70 and 30%, respectively, and the experiments were carried out with recycle of treated wastewater at different percentage as 10, 20, 30 and 40. Maximum removal of COD and colour was 96% and 93.3%, respectively, at 30% recycle. At various OLR and HRT, the maximum removal of COD, colour was 95.9%, 93% at 6.81 kg COD/m³d and 96%, 93% with 24 h of HRT. The maximum production of biogas at 24 h of HRT with 30% recycle was about 355 l/d. The Volatile fatty acid/Alkalinity ratio of methanogenic reactor was found to be 0.049–0.053. The result provided evidence, the starch and dye wastewater have wide variation in their characteristics was treated on combination, this new technology supports the effective utilization of starch waste in destruction of dye.     

豆壳过氧化物酶的盐酸胍变性与化学修饰研究

研究了盐酸胍对豆壳过氧化物酶(soybeanhullperoxidase,SHP,EC1.11.1.7)构象与活力的影响,发现去辅基SHP的盐酸胍变(复)性及荧光变化关系与SHP全酶分子的盐酸胍变(复)性及荧光变化关系明显不同。应用过碘酸氧化法去除SHP分子表面糖链,研究糖链去除对酶性质的影响,则证实了SHP分子表面的糖链去除导致酶热稳定性下降。应用不同的蛋白质侧链修饰剂对SHP进行化学修饰则表明,巯基、酪氨酸和色氨酸残基为酶活力非必需,而羧基、组氨酸和精氨酸残基为酶活力所必需。     

Adsorption of Methylene Blue Dye on Pure and Carbonized Water Weeds

The influence of process variables in batch adsorption has been used to assess the removal of methylene blue dye from aqueous solution using pure and carbonized biomasses of water hyacinth and water spinach. Dried leaves of the water weeds were carbonized at temperature up to 750°C. The optimum removal of dye was achieved at pH 10, 30°C, and 55 min at a dye concentration of 10 mg/L. In an attempt to describe the adsorption process, the equilibrium isotherm for each adsorbent was determined using Langmuir and Freundlich adsorption isotherm models. Maximum adsorption capacities based on the Langmuir model for pure and carbonized water hyacinth were (mg/g) 7.05 and 2.07, respectively, whereas those of pure and carbonized water spinach were 1.25 and 5.32, respectively. It was observed that the equilibrium data were well fit by both the Freundlich and Langmuir isotherms as R ² > .97. This study demonstrates that the two waterweeds are effective, environmentally friendly, and inexpensive biomaterials for the removal of color from industrial effluents.     

Effective bioremoval of reactive dye and heavy metals by Aspergillus versicolor

In this study, bioaccumulation of heavy metal and dye by Aspergillus versicolor was investigated. Optimum pH values of the maximum heavy metal bioaccumulation was found as 6 for 50 mg/L Cr(VI), Ni(II) and 5 for Cu(II) ions with the 99.89%, 30.05% and 29.06% removal yield, respectively. The bioremoval of the dye up to 800 mg/L at pH 5 and 6 was investigated and 27.15% and 28.95% removal rates were measured respectively. The presence of Cr(VI) with dye, decreased the uptake yield for both pollutants. In the medium with Cu(II) and dye, dye removal was not affected by Cu(II), but Cu(II) removal rate increased from 29.06% to 37.91% by the existence of the dye. When Ni(II) and dye were combined, neither pollutant affected the other’s removal yield. These results indicate that the isolated A. versicolor strain deserves attention as a promising bioaccumulator of heavy metal ions and reactive dyes in wastewater effluents.     

Effect of nutritional conditions on dye removal from textile effluent by <Emphasis Type="Italic">Aspergillus lentulus</Emphasis>

The nutritional conditions supporting growth and maximum dye removal by Aspergillus lentulus have been investigated. Initially a composite media containing yeast extract, glucose and mineral components was used and the effect of various components on dye removal was studied. For maximum dye removal (≈100%), ≥0.5% (w/v) glucose and ≥0.25% (w/v) yeast extract were essential. While glucose played an important role in pellet formation, which in turn was important for dye removal, yeast extract contributed towards higher biomass production. Mineral components (except NH₄NO₃) did not affect dye removal significantly. Next the alternate sources of carbon (molasses, jaggery, starch and sodium acetate) and nitrogen (peptone, urea, ammonium nitrate, sodium nitrate and ammonium chloride) were tested. Among carbon sources, all the sources produced almost complete dye removal in 48 h (more than 97% in 24 h), except sodium acetate (64% in 48 h). All the tested nitrogen sources resulted in >90% dye removal in 48 h. Yeast extract and peptone gave best results with high dye removal rate (9.8 and 8.1 mg/l/h, respectively). However, among the low cost alternates, urea and NH₄Cl came out to be suitable sources due to the high uptake capacity of the biomass produced coupled with high dye removal rate in case of NH₄Cl. Therefore, a combination of urea and NH₄Cl was tested, which produced complete dye removal with a high dye removal rate (10 mg/l/h). Finally the modified composite media containing urea and NH₄Cl as nitrogen sources and glucose as carbon source was utilized for effluent treatment. Results indicated that performance of modified composite media was at par with composite media for supporting growth of A. lentulus and dye removal from the textile effluent.     

Abatement of microfibre pollution and detoxification of textile dye – Indigo by engineered plant enzymes

Microfibres (diameter <5 mm) and textile dyes released from textile industries are ubiquitous, cause environmental pollution, and harm aquatic flora, fauna, animals and human life. Therefore, enzymatic abatement of microfibre pollution and textile dye detoxification is essential. Microbial enzymes for such application present major challenges of scale and affordability to clean up large scale pollution. Therefore, enzymes required for the biodegradation of microfibres and indigo dye were expressed in transplastomic tobacco plants through chloroplast genetic engineering. Integration of laccase and lignin peroxidase genes into the tobacco chloroplast genomes and homoplasmy was confirmed by Southern blots. Decolorization (up to 86%) of samples containing indigo dye (100 mg/L) was obtained using cp-laccase (0.5% plant enzyme powder). Significant (8-fold) reduction in commercial microbial cellulase cocktail was achieved in pretreated cotton fibre hydrolysis by supplementing cost effective cellulases (endoglucanases, ß-glucosidases) and accessory enzymes (swollenin, xylanase, lipase) and ligninases (laccase lignin peroxidase) expressed in chloroplasts. Microfibre hydrolysis using cocktail of Cp-cellulases and Cp-accessory enzymes along with minimal dose (0.25% and 0.5%) of commercial cellulase blend (Ctec2) showed 88%–89% of sugar release from pretreated cotton and microfibres. Cp-ligninases, Cp-cellulases and Cp-accessory enzymes were stable in freeze dried leaves up to 15 and 36 months respectively at room temperature, when protected from light. Use of plant powder for decolorization or hydrolysis eliminated the need for preservatives, purification or concentration or cold chain. Evidently, abatement of microfibre pollution and textile dye detoxification using Cp-enzymes is a novel and cost-effective approach to prevent their environmental pollution.     

Decolorization of chemically different dyes by white-rot fungi in submerged cultures

Forty-two white-rot fungi in submerged cultures were tested to determine their dye decolorization capacity and the optimal conditions for the decolorization process. Trametes pubescens Cui 7571 was found to be the most effective strain in terms of decolorization performance on the azo dye Congo Red, and it exhibited excellent reusability as well as persistence in sequential decolorization experiments. Optimization of the decoloration process was also conducted to evaluate the effects of a number of chemical compounds, metal salts, inducers, and mediators on the dye decolorization rate. On the seventh day, a highest dye removal of 98.83 % was observed with addition of copper at 2.5 mmol L^?1, Tween 80 at 1.0 % (v/v), and ferulic acid at 0.50 μmol L^?1, respectively. The adsorption of mycelia to dyes was not a significant contributor to dye removal, and decolorization by the functional fungus T. pubescens depended on biodegradation by enzymes, as evidenced by the results of the moist heat sterilization treatment (121°C for 20 min), induction of extracellular enzymes, and scanning electron microscopy. Four dye degradation metabolites, i.e., naphthalene amine, biphenyl amine, biphenyl ,and naphthalene diazonium, were identified by Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry. The phytotoxicity tests indicated that degraded metabolites had almost a negligible effect on the plant seeds as compared to that of dye, which is indicative of the less toxic nature of the metabolites. Our results suggest that white-rot fungus T. pubescens could be developed into a novel azo dye bioremediation strategy.     

Effect of pretreatments of three waste residues,wheat straw,corncobs and barley husks on dye adsorption

The removal of dyes (Cibacron Yellow C-2R, Cibacron Red C-2G, Cibacron Blue C-R, Remazol Black B and Remazol Red RB) from an aqueous solution has been discussed by adsorption which was examined on three different low cost pretreated agricultural residues viz., wheat straw, corncob and barley husk. The pretreatments were carried out in order to delignify, or to increase the surface area of the sorbents, and to study their effect on the rate and effective adsorption of dyes. Steam, alkali, ammonia steeping and milling were the pretreatments employed and compared with the untreated sorbents. A higher percentage of dye removal was achieved at a faster rate by the milled samples proving milling to be a better and more cost effective treatment, except for barley husk which had a higher percentage removal for the control.     

Fish (Labeo rohita) Scales as Potential Low-Cost Biosorbent for Removal of Malachite Green from Aqueous Solutions

The feasibility of using fish (Labeo rohita) scales as low-cost biosorbent for the removal of hazardous Malachite Green (MG) dye from aqueous solutions was investigated. Employing a batch experimental setup, the effect of operational parameters such as biosorbent dose, initial solution pH, contact time, and temperature on the dye removal process was studied. The equilibrium biosorption data followed both Langmuir and Freundlich isotherm models, whereas the experimental kinetic data fitted well to the pseudo-second-order kinetic model. Thermodynamic study indicated spontaneous and endothermic nature of the biosorption process. The results suggest that fish scales could be used as an effective biosorbent for removal of MG dye from aqueous solutions.     

Evaluation of colour removal in synthetic saline wastewater containing azo dyes using an immobilized halotolerant cell system

Studies were carried out to evaluate the colour removal capacity of a moderately halotolerant bacterium, Bacillus firmus, in synthetic saline wastewater medium (SSWM) under static condition. The bacterial strain effectively decolourized Polar red B (an azo dye) in a wide range of sodium chloride (1-6%, w/v), dye (5-100 mg/L) and SDS (0.1-5.0 mg/L) concentrations and at pH range of 6-10 after 24 h of incubation. Cell immobilization studies indicated that colour removal was significantly higher (p < 0.05) in immobilized halotolerant cell systems than with free cells of B. firmus especially at salt concentrations higher than 4%. Results suggest the potential of using the immobilized halotolerant cell system for effective treatment of dye-contaminated saline wastewaters.