Chitosan-coated Lentinus polychrous Lév.: Integrated biosorption and biodegradation systems for decolorization of anionic reactive dyes

Research and development of an effective color removal system is needed to reduce the severity of water pollution caused by effluent that contains dyes. In this study, the integrated biosorption and biodegradation system of chitosan coated Lentinus polychrous Lév. was developed and evaluated for its decolorization efficiency with regard to anionic reactive dye mixtures of Reactive Blue 19, 160, and 198. The fungi were coated with 0.1, 0.5, and 1.0% w/v of low molecular weight chitosan. The scanning electron micrographs confirmed that chitosan was successfully coated on the surface of the fungi. Studies of changes in UV–visible absorption spectra, dye desorption, ligninolytic enzyme activity, and Fourier transform infrared spectroscopy showed that within 6 h, the biosorption was the control mechanism and the dyes were reduced to 91.50, 77.66, 37.39, and 26.93% by the fungi coated with 0, 0.1, 0.5, and 1.0% w/v chitosan, respectively. From the 36th hour to the end of colorization at the 72nd hour, the fungal biodegradation by laccase and manganese peroxidase was dominant and all treatments had 5–8% of the dye remaining. Therefore, the chitosan coat acted as an efficient biosorbent for the anionic reactive dyes, thereby effectively improving the decolorization efficiency of the white rot fungus.     

Microbial decolorization of azo dyes and dye industry effluent by Fomes lividus

The white rot fungus, Fomes lividus, was isolated from the logs of Shorea robusta in the Western Ghats region of Tamil Nadu, India. The fungus was tested for decolorization of azo dyes such as orange G (50 M) congo red (50 M) amido black 10B (25 M) and also for colour removal from dye industry effluents. The results revealed that the fungus could remove only 30.8% of orange G in the synthetic solution, whereas congo red and amido black 10B were removed by 74.0 and 98.9% respectively. A dye industry effluent was treated by the fungus in batch and continuous mode. In batch mode treatment, a maximum decolorization of 84.4% was achieved on day 4, and in continuous mode a maximum decolorization of 37.5% was obtained on day 5. The colour removal by the basidiomycete fungus might be due to adsorption of the dyes to the mycelial surface and metabolic breakdown. These results suggested that the batch mode treatment of Fomes lividus is one of the most efficient ways for colour removal in dye industry effluents.     

Biosorption of reactive dye by waste biomass of Nostoc linckia

Potential of spent biomass of a cyanobacterium, Nostoc linckia HA 46, from a hydrogen bioreactor was studied for biosorption of a textile dye, reactive red 198. The waste biomass was immobilized in calcium alginate and used for biosorption of the dye from aqueous solution using response surface methodology (RSM). Kinetics of the dye in aqueous solution was studied in batch mode. Interactive effects of initial dye concentration (100-500 mg/L), pH (2-6) and temperature (25-45 °C) on dye removal were examined using Box-Behnken design. Maximum adsorption capacity of the immobilized biomass was 93.5 mg/g at pH 2.0, initial concentration of 100 mg/L and 35 °C temperature, when 94% of the dye was removed. Fourier transform infrared (FT-IR) studies revealed that biosorption was mainly mediated by functional groups like hydroxyl, amide, carboxylate, methyl and methylene groups present on the cell surface.     

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.     

Decolorization of reactive dyes by mixed cultures isolated from textile effluent under anaerobic conditions

In the present study mixed cultures that could grew in the molasses media were isolated from textile dye effluent and its decolorization activity was studied in a batch system under anaerobic conditions, in order to determine the optimal conditions required for the highest decolorization activity. The optimum pH value for decolorization was determined as 8 for all the dyes tested. In the experiment with pH 8 dye decolorizations by mixed cultures were investigated at about 96.2–1031.3 mg l⁻¹ initial dye concentrations. The highest dye removal rates of mixed cultures were 94.9% for Reactive Red RB, 91.0% for Reactive Black B and 63.6% for Remazol Blue at 953.2, 864.9 and 1031.3 mg l⁻¹ initial dye concentrations respectively within 24 h incubation period. When the Reactive Red RB was used, approximately 82–98% total color removal was obtained at between 96.2 and 953.2 mg l⁻¹ initial dye concentrations after 12 h of incubation at 35 °C. These results show that our enriched mixed cultures have the potential to serve as an excellent biomass for the use in reactive dye removal from wastewaters under anaerobic conditions.     

Decolorization of a dye industry effluent by <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> XC6

The strain Aspergillus fumigatus XC6 isolated from mildewing rice straw was evaluated for its ability to decolorize a dye industry effluent. The strain was capable of decolorizing dyes effluent over a pH range 3.0–8.0 with the dyes as sole carbon and nitrogen sources. The optimum pH was 3.0; however, supplemented with either appropriate nitrogen sources (0.2% NH₄Cl or (NH₄)₂SO₄ ) or carbon sources (1.0% sucrose or potato starch), the strain decolorized the effluent completely at the original pH of the dyes effluent. Therefore, A. fumigatus XC6 is an efficient strain for the decolorization of reactive textile dyes effluents, and it might be a practical alternative in dyeing wastewater treatment.     

Contributions of functional groups and extracellular polymeric substances on the biosorption of dyes by aerobic granules

The contributions of loosely bound extracellular polymeric substances (LB-EPS), tightly bound EPS (TB-EPS), residual sludge (the sludge left after EPS extraction) and functional groups such as amine, carboxyl, phosphate and lipid on aerobic granules on biosorption of four different dyes (Reactive Brilliant Blue KN-R (KN-R), Congo Red (CR), Reactive Brilliant Red K-2G (RBR) and Malachite Green (MG)) were investigated. EPS may be responsible for biosorption of cationic dyes. However, residual sludge always made greater contribution than that of EPS. The biosorption mechanisms were dependent on the functional groups on aerobic granules and dyes’ chemical structures. The lipid and phosphate groups might be the main binding sites for KN-R biosorption. Amine, carboxyl, phosphate and lipid were all responsible for the binding of CR. The lipid fractions played an important role for RBR biosorption. For MG, the phosphate groups gave the largest contribution.     

Different bioreactor configurations for the decolourisation of the azo dye reactive black 5 by Geotrichum sp. CCMI 1019

Decolourisation of the azo dye Reactive Black 5 by Geotrichum sp. CCMI 1019 was studied using stirred tank reactors (STR) and two types of bubble columns (porous plate (PP) bubble column and aeration tube (AT) bubble column). For the bubble columns, the k_La increased with the gas fractional hold-up (ε_G) and the aeration rate. A linear relationship between ε_G and superficial gas velocity was obtained for all reactors. At same aeration rates, the PP bubble columns showed higher k_La and hold-up values than the AT bubble column. In the STRs, large and dense aggregates were formed which adhered to surfaces whereas bubble columns gave smaller and less compact pellets.

Manganese peroxidase and laccase were detected in the extracellular media in all reactors. However, laccase was only detected after the onset of decolourisation, suggesting that additional enzymes may be involved. Mn peroxidase activity was detected (about 46 U/ml) in both the STRs and AT bubble columns but higher values (110 U/ml) were obtained with the PP bubble columns.

Out of the three reactor systems studied, the AT bubble columns gave the most favourable results for Reactive Black 5 decolourisation. Rapid and complete colour removal was obtained throughout the visible spectrum. Bubble columns are simple in design as well as operation and may be useful for the bioremediation of textile wastewater.     

Different bioreactor configurations for the decolourisation of the azo dye reactive black 5 by Geotrichum sp. CCMI 1019

Decolourisation of the azo dye Reactive Black 5 by Geotrichum sp. CCMI 1019 was studied using stirred tank reactors (STR) and two types of bubble columns (porous plate (PP) bubble column and aeration tube (AT) bubble column). For the bubble columns, the k_La increased with the gas fractional hold-up (ε_G) and the aeration rate. A linear relationship between ε_G and superficial gas velocity was obtained for all reactors. At same aeration rates, the PP bubble columns showed higher k_La and hold-up values than the AT bubble column. In the STRs, large and dense aggregates were formed which adhered to surfaces whereas bubble columns gave smaller and less compact pellets.

Manganese peroxidase and laccase were detected in the extracellular media in all reactors. However, laccase was only detected after the onset of decolourisation, suggesting that additional enzymes may be involved. Mn peroxidase activity was detected (about 46 U/ml) in both the STRs and AT bubble columns but higher values (110 U/ml) were obtained with the PP bubble columns.

Out of the three reactor systems studied, the AT bubble columns gave the most favourable results for Reactive Black 5 decolourisation. Rapid and complete colour removal was obtained throughout the visible spectrum. Bubble columns are simple in design as well as operation and may be useful for the bioremediation of textile wastewater.     

Aerobic decolorization and detoxification of a disperse dye in textile effluent by a new isolate of Bacillus sp

A number of aerobic species capable of decolorizing some of the dyes in a textile mill effluent were isolated. One of the isolates was able to decolorize Terasil black dye under aerobic conditions in the presence of an exogenous carbon source after 5 days. Glucose or starch (%1 ea) are essential for decolorization but the process proceeds faster in the presence of 0.5% yeast extract. Results of the BOD(5) show that the untreated effluent samples have a low BOD value, whereas treated samples show an initial increase in BOD up to 15 days followed by a decrease after 20 days. FT-IR and GC-MS data also reveal that the initial components in the untreated effluent disappear after 20 days of treatment, confirming biodegradation of the dye. Phytotoxicity tests on the untreated effluent samples using the seeds of Lens orientalis, Triticum aestivum, and Triticum boeoticum indicate that the first one is the most sensitive while the last one is the most resistant. On the other hand the treated effluent allows 90% germination in Triticum boeoticum seeds and 100% germination in the other two.     

Contribution of sludge adsorption and biodegradation to the removal of five pharmaceuticals in a submerged membrane bioreactor

A submerged membrane bioreactor was set up to investigate the removal efficiencies of five pharmaceuticals from synthetic domestic wastewater. Batch experiments were conducted with sterilized sludge and activated sludge to explore the contributions of sludge adsorption and biodegradation for those pharmaceuticals. Notable difference of those pharmaceuticals removal efficiencies was observed, at about 92.2, 90.0, 55.4, 38.5 and 3.2% for acetaminophen, 17β-estradiol, naproxen, diclofenac sodium, and carbamazepine, respectively. Results of batch adsorption experiments via sterilized sludge showed that the removal efficiencies of five pharmaceuticals by sludge adsorption were 7.9, 68.2, 60.1, 40.1 and 71.5%, respectively, which were positively correlated with their octanol–water partition coefficients. Results of batch experiments via activated sludge showed that 83.4% of acetaminophen, 98.0% of 17β-estradiol, and 46.8% of naproxen were removed through the combination of sludge adsorption and biodegradation, while adsorption accumulation in sludge phase was only 1.8, 1.3 and 7.0%. This implies that the removals of these three drugs were mainly achieved by biodegradation. The total removal efficiency of diclofenac sodium was 19.7%, and the contributions of sludge adsorption and biodegradation were 14.9 and 4.8%, which indicated that the removal of diclofenac sodium was mainly achieved by sludge adsorption. The total removal efficiency of carbamazepine was only 8.9% and this implies that neither sludge adsorption nor biodegradation is effective for its removal.     

活性X-3B红染料对作物生态毒理指标影响的比较研究

采用作物种子暴露实验 ,研究了小麦、白菜和水稻等 3种不同作物对活性X 3B红染料污染暴露的生态毒理学指标 .结果表明 ,小麦、白菜和水稻对活性X 3B红染料污染暴露的反应各异 ,具体表现为对3种作物的种子发芽抑制半效应浓度分别为 896 5、70 10和 75 14mg·L-1,对根伸长抑制的半效应浓度分别为 6 5 34、5 882和 45 70mg·L-1;这 3种作物在从种子萌发起至第 7天时去残余种子或种皮后的鲜生物量、干生物量均随活性X 3B红暴露浓度的增加而降低 ,但鲜生物量的降低率普遍高于干生物量的降低率 ;当作物种子暴露于高浓度 (4 5 0 0和 5 0 0 0mg·L-1)的活性X 3B红时 ,小麦生物量受该有机染料污染暴露的影响最为敏感 ,水稻其次 ,白菜最为迟钝 ;就小麦、白菜和水稻等 3种作物对活性X 3B红染料污染暴露的抗性而言 ,小麦最强 ,白菜次之 ,水稻最弱 .     

Anthraquinone dye assisted the decolorization of azo dyes by a novel Trametes trogii laccase

A new Trametes trogii laccase was purified and its biochemical properties were subsequently characterized. After a survey of other T. trogii laccases, this laccase showed a lower isoelectric point, different N-terminal sequence and kinetic parameters. Recently most laccase-catalyzed decolorizations of synthetic dyes are single-solute studies with commercially available dyes as model pollutants and need the employment of redox mediators. In this study, to simulate the real industry wastewaters, experiments of laccase-catalyzed decolorization of mixed dyes constituted by azo and anthraquinone dyes were carried out. The results showed that anthraquinone dyes, playing the role of mediators, dramatically promoted the degradation of azo dyes when there was no exogenous mediator in the reaction mixture. This study represents the first attempt to decolorize the mixtures of azo and anthraquinone dyes by purified T. trogii laccase, suggesting great potential for laccase to decolorize textile industry wastewaters.     

A new approach to the study of genetic variability of complex characters

A new approach to multivariate genetic analysis of complex organismal traits is developed. It is based on examination of the distribution of parental strains and the F1 and F2 hybrids in a multidimensional space, and the determination of the directions corresponding to heterozygosity, epistatic and additive gene effects. The effect of heterozygosity includes variability produced by interaction between and within heterozygous loci. The additive gene effects and the remaining epistatic interactions between the homozygous loci can be visualized separately from the effects of heterozygosity by an appropriate projection of the points in multidimensional space. In all, 20 morphological, physiological and behavioural characters and 21 craniometric measures were studied in crosses between two laboratory rat strains. Linear combinations of craniometric and of morphophysiological characters with a high narrow-sense heritability could be identified. These combinations characterized the organismal stress response, which had been selected for in one of the strains. The prospects for the practical application of the new approach and also for the evaluation of the contribution of the genetic diversity to phenotypic variability in animals in natural populations are discussed.     

A modified technique for the measurement of sulfhydryl groups oxidized by reactive oxygen intermediates

This paper suggests a simple modification of the Ellman procedure when used to measure accurate changes in sulfhydryl (-SH) content induced by reactive oxygen intermediates (ROI). This modification became necessary when we found that the standard technique did not produce time invariant results in the presence of ROI-generating systems. Cysteine (cys; 20–100 μM) in 20 mM imidazole buffer (pH 7.0) containing 1.0 mM EDTA was reacted with excess (0.2 mM) 5,5′-dithiobis(2-nitrobenzoic acid), DTNB. The absorbance of the product (p-nitrothiophenol anion) was recorded at 412 nm (A₄₁₂). This A₄₁₂ was stable for 60 min and gave a linear relationship with cys concentrations used. ROI were generated either by 0.01 U xanthine oxidase (XO) + 0.01–1.0 mM hypoxanthine (HX), 0.01–1.0 mM H₂O₂, or H₂O₂ + 100 μM FeSO₄. In the presence of ROI, A₄₁₂ decreased with time and its rate of decrease was dependent upon the concentration of components of the ROI-generating system. This time-dependent decrease in A₄₁₂ was prevented completely by the addition of 100 U of catalase (CAT). Therefore, we modified the DTNB method as follows: -SH groups were reacted with ROI for 30 min; this was followed by the addition of 100 U of CAT to scavenge the excess unreacted ROI before the addition of DTNB to generate the product. Using this modification the ROI-induced decrease in A₄₁₂ was stable with time and was linearly related to the cys concentration. We further tested the modified procedure using metallothionein (MT) as a substrate for the ROI-induced changes in -SH content. MT, at concentrations of 2.5, 5.0, and 7.5 μM, was treated with XO + 100 μM HX. Using the modified procedure, an average decrease (as compared to the untreated control) of 15, 22, and 33 μM in -SH content was observed consistently at the respective MT concentrations. However, without the modification in the procedure, these average decrease were 20, 38, and 51 μM, respectively and continued to further increase with time. These discrepancies could give rise to errors ranging from 28 to 35% or higher in determination of the ROI-induced decrease in the -SH groups of MT. This data suggests that scavenging the unreacted H₂O₂ with C prior to the addition of DTNB to the assay mixture gives a stable and accurate estimate of the ROI-induced oxidative damage to -SH groups.     

A microcontact printing approach to the immobilization of oligonucleotide brushes

Solution hybridized oligonucleotides were immobilized onto surfaces via micro-contact printing. Besides micro-patterning of the substrate, sequential dehybridization and rehybridization were monitored via laser scanning microscopy, which assess the surface tethering of the oligonucleotides into a brush.     

A new paradigm for the action of reactive oxygen species in the photoinhibition of photosystem II

Inhibition of the activity of photosystem II (PSII) under strong light is referred to as photoinhibition. This phenomenon is due to the imbalance between the rate of photodamage to PSII and the rate of the repair of damaged PSII. Photodamage is initiated by the direct effects of light on the oxygen-evolving complex and, thus, photodamage to PSII is unavoidable. Studies of the effects of oxidative stress on photodamage and subsequent repair have revealed that reactive oxygen species (ROS) act primarily by inhibiting the repair of photodamaged PSII and not by damaging PSII directly. Thus, strong light has two distinct effects on PSII; it damages PSII directly and it inhibits the repair of PSII via production of ROS. Investigations of the ROS-induced inhibition of repair have demonstrated that ROS suppress the synthesis de novo of proteins and, in particular, of the D1 protein, that are required for the repair of PSII. Moreover, a primary target for inhibition by ROS appears to be the elongation step of translation. Inhibition of the repair of PSII by ROS is accelerated by the deceleration of the Calvin cycle that occurs when the availability of CO₂ is limited. In this review, we present a new paradigm for the action of ROS in photoinhibition.     

The complex interplay of iron metabolism,reactive oxygen species,and reactive nitrogen species: Insights into the potential of various iron therapies to induce oxidative and nitrosative stress

Production of minute concentrations of superoxide (O₂⁻) and nitrogen monoxide (nitric oxide, NO) plays important roles in several aspects of cellular signaling and metabolic regulation. However, in an inflammatory environment, the concentrations of these radicals can drastically increase and the antioxidant defenses may become overwhelmed. Thus, biological damage may occur owing to redox imbalance—a condition called oxidative and/or nitrosative stress. A complex interplay exists between iron metabolism, O₂⁻, hydrogen peroxide (H₂O₂), and NO. Iron is involved in both the formation and the scavenging of these species. Iron deficiency (anemia) (ID(A)) is associated with oxidative stress, but its role in the induction of nitrosative stress is largely unclear. Moreover, oral as well as intravenous (iv) iron preparations used for the treatment of ID(A) may also induce oxidative and/or nitrosative stress. Oral administration of ferrous salts may lead to high transferrin saturation levels and, thus, formation of non-transferrin-bound iron, a potentially toxic form of iron with a propensity to induce oxidative stress. One of the factors that determine the likelihood of oxidative and nitrosative stress induced upon administration of an iv iron complex is the amount of labile (or weakly-bound) iron present in the complex. Stable dextran-based iron complexes used for iv therapy, although they contain only negligible amounts of labile iron, can induce oxidative and/or nitrosative stress through so far unknown mechanisms. In this review, after summarizing the main features of iron metabolism and its complex interplay with O₂⁻, H₂O₂, NO, and other more reactive compounds derived from these species, the potential of various iron therapies to induce oxidative and nitrosative stress is discussed and possible underlying mechanisms are proposed. Understanding the mechanisms, by which various iron formulations may induce oxidative and nitrosative stress, will help us develop better tolerated and more efficient therapies for various dysfunctions of iron metabolism.     

Biosorption of reactive dyes by the mycelium pellets of a new isolate of Penicillium oxalicum

Three reactive dyes were rapidly adsorbed by the mycelium pellets of Penicillium oxalicum. Dye removal of Reactive Blue 19 was up to 60% in 10 min and 91% in 80 min. Dye adsorption isotherms fitted Langmuir model well and the maximum adsorption capacities at 20 °C were calculated to be 160 mg g^–1 for Reactive Blue 19, 122 mg g^–1 for Reactive Red 241 and 137 mg g^–1 for Reactive Yellow 145, respectively. The pellets exhibited a high dye adsorption capacity (80–180 mg g^–1) for all of the 3 dyes over a wide pH range (pH 2–10), and the maximum adsorption was obtained at pH 2. The adsorption capacity was mildly increased by increasing salinity.