Development of novel enzymatic bioremediation process for textile industry effluents through response surface methodology

Introducing Polyhydroxyurethane Hydrogels and Coatings for Formaldehyde Capture

Formaldehyde (FA) is a harmful chemical product largely used for producing resins found in our living spaces. Residual FA that leaches out the resin contributes to our indoor air pollution and causes some important health issues. Systems able to capture this volatile organic compound are highly desirable; however, traditional adsorbents are most often restricted to air filtration systems. Herein, we report novel waterborne coatings that are acting as a FA sponge for indoor air decontamination. These coatings, of the poly(hydroxyurethane) (PHU) type, rich in primary amine groups, are prepared by the polyaddition of a hydrosoluble dicyclic carbonate to a polyamine in water at room temperature under catalyst-free conditions. We highlight the importance of the choice of the polyamine on the curing rate of the formulation and on the FA capture ability of PHU. The excellent FA capturing ability of the best candidate is rationalized by investigating the action mode of the polyamine used to construct PHUs. With poly(vinyl amine), FA is covalently and permanently bound to PHU, with no release over time. The performance of the coating in FA abatement is impressive, with more than 90% of captured FA after one day of contact. The facility to prepare these transparent and colorless coatings from waterborne formulations gives access to new efficient indoor air depolluting solutions, potentially applicable to various surfaces of our living spaces (wall, ceiling, etc.).

Recent trends in extraction of plant bioactives using green technologies: A review

Phenolic compounds from plant sources have significant health-promoting properties and are known to be an integral part of folk and herbal medicines. Consumption of phenolics is known to alleviate the risk of various lifestyle diseases including cancer, cardiovascular, diabetes, and Alzheimer's. In this context, numerous plant crops have been explored and characterized based on phenolic compounds for their use as supplements, nutraceutical, and pharmaceuticals. The present review highlights some important source of bioactive phenolic compounds and novel technologies for their efficient extraction. These techniques include the use of microwave, ultrasound, and supercritical methods. Besides, the review will also highlight the use of response surface methodology (RSM) as a statistical tool for optimizing the recoveries of the phenolic bioactives from plant-based matrices.

Decolorization of Textile Effluent by Trametes hirsuta Bm-2 and lac-T as Possible Main Laccase-Contributing Gene

The decolorization of dye and textile effluent by Trametes hirsuta was studied in both induced and non-induced media. A removal of 70-100% of the color was achieved through adsorption and the action of laccases. Laccase activity was increased significantly with the addition of grapefruit peel (4000 U/mL) and effluent with grapefruit peel (16,000 U/mL) in comparison with the basal medium (50 U/mL). Analysis of the expression of laccase isoenzymes lac-B and lac-T revealed clear differences in the expression of these genes. The low levels of expression of lac-B in all media suggest a basal or constitutive gene expression, whereas lac-T was over-expressed in the media with effluent, and showed an up/down regulation depending on culture conditions and time. The results obtained suggest that the lac-T gene of T. hirsuta is involved in the decolorization of dyes.

Modeling and optimization by particle swarm embedded neural network for adsorption of methylene blue by jicama peroxidase immobilized on buckypaper/polyvinyl alcohol membrane

Jicama peroxidase (JP) immobilized functionalized Buckypaper/Polyvinyl alcohol (BP/PVA) membrane was synthesized and evaluated as a promising nanobiocomposite membrane for methylene blue (MB) dye removal from aqueous solution. The effects of independent process variables, including pH, agitation speed, initial concentration of hydrogen peroxide (H₂O₂), and contact time on dye removal efficiency were investigated systematically. Both Response Surface Methodology (RSM) and Artificial Neural Network coupled with Particle Swarm Optimization (ANN-PSO) approaches were used for predicting the optimum process parameters to achieve maximum MB dye removal efficiency. The best optimal topology for PSO embedded ANN architecture was found to be 4-6-1. This optimized network provided higher R² values for randomized training, testing and validation data sets, which are 0.944, 0.931 and 0.946 respectively, thus confirming the efficacy of the ANN-PSO model. Compared to RSM, results confirmed that the hybrid ANN-PSO shows superior modeling capability for prediction of MB dye removal. The maximum MB dye removal efficiency of 99.5% was achieved at pH-5.77, 179 rpm, ratio of H₂O₂/MB dye of 73.2:1, within 229 min. Thus, this work demonstrated that JP-immobilized BP/PVA membrane is a promising and feasible alternative for treating industrial effluent.

Molecular characterization of laccase genes from the basidiomycete Trametes hirsuta Bm-2 and analysis of the 5' untranslated region (5'UTR)

The aim of this study was to identify and characterize laccase genes produced by Trametes hirsuta Bm-2 in a liquid medium, both with and without induction. The amplification of 5'and 3'regions of laccase sequences was obtained by the RACE-PCR method, and these were assembled to obtain a cDNA of total length. Two new laccase genes were isolated from basal medium (lac-B) and lignocellulosic grapefruit substrate (lac-T), both encoding open reading frames of 2566 bp. Both laccase-predicted proteins consisted of 521 amino acids, four copper-binding regions, a signal peptide, and five potential glycosilation sites (Asn-Xaa-Ser/Tre). Moreover, the deduced amino acid sequences share about 76-85% identity with other laccases of WRF. Sequence comparison showed 47 synonymous point mutations between lac-B and lac-T. In addition, 5' untranslated regions (UTR) of laccase genes lac-B and lac-T showed differences in length and number of regulatory elements that may affect transcriptional or translational expression of these genes.

Possibilities of Obtaining from Highly Polluted Environments: New Bacterial Strains with a Significant Decolorization Potential of Different Synthetic Dyes

The aim of this study was the isolation of bacterial strains which have the ability to decolorize synthetic dyes belonging to different chemical groups. The samples for bacterial isolation were collected from aqueous environments-two activated sludges and polluted local river. At the first stage of screening (performed on the solid media supplemented with two dyes-azo Evans blue or triphenylmethane brilliant green), 67 bacterial strains were isolated capable to decolorize the used dyes. In the further study, six dyes with different chemical structures were used: fluorone dyes (Bengal rose, erythrosine), triphenylmethane dyes (brilliant green, crystal violet), azo dyes (Evans blue, Congo red). Initial concentration of each of these chemicals in samples was 0.1 g/l. Obtained results showed that only 31 isolates were able to decolorize all six used dyes (with different efficiencies). Among them, 11 strains were isolated from the river (55% of isolates from this site) and 20 from activated sludges collected from two different treatment plants (15 from the first water treatment plant and 5 from the second which were 42 and 43% of isolated cultures respectively). The decolorizing microorganisms are mostly isolated from different industrial sewages (e.g., textile industry), but results of the study showed that water from polluted river as well as municipal wastewaters may be a precious source for isolation of bacterial strains with the wide spectrum and high decolorization potential. In general, there were no statistically significant differences between decolorization abilities of strains isolated from different sites. The group of dyes that was removed with the highest yield was triphenylmethanes (75.6%), followed by fluorones (70.0%) and azo group (60.9%). The analysis of decolorization efficiency of the individual dyes revealed the best removal results in case of triphenylmethane brilliant green (average removal 85.7%), followed by fluorone erythrosine (average removal 78.9%), triphenylmethane crystal violet (average removal 65.5%), azo Evans blue (average removal 64.4%), fluorone Bengal rose (average removal 61.0%), and azo Congo red (average removal 57.4%). Obtained results revealed that the dye susceptibility to decolorization depends on the characteristic chemical structure of given dye groups but more important is chemical structure of strictly given dye within the group.

Characteristic features and dye degrading capability of agar-agar gel immobilized manganese peroxidase

Immobilization of enzymes has been regarded as an efficient approach to develop biocatalyst with improved activity and stability characteristics under reaction conditions. In the present study, purified manganese peroxidase (MnP) from Ganoderma lucidum IBL-05 was immobilized in agar-agar support using entrapment technique. Maximum immobilization yield was accomplished at 4.0% agar-agar gel. The immobilized MnP exhibited better resistance to changes in pH and temperature than the free enzyme, with optimal conditions being pH 6.0 and 50 °C. The kinetic parameters Km and Kcat/Km for free and entrapped MnP were calculated to be 65.6 mM and 6.99 M(-1) s(-1), and 82 mM and 8.15 M(-1) s(-1), respectively. Thermo-stability was significantly improved after immobilization. After 120 h, the insolubilized MnP retained its activity up to 71.9% and 60.3% at 30 °C and 40 °C, respectively. It showed activity until 10th cycle and retained 74.3% residual activity after 3th cycle. The effects of H2O2, ionic strength and potential inhibitors on activity of free and immobilized enzyme were investigated. Moreover, the decolorization of three structurally different dyes was monitored in order to assess the degrading capability of the entrapped MnP. The decolorization efficiencies for all the tested dyes were 78.6-84.7% after 12h. The studies concluded that the toxicity of dyes aqueous solutions was significantly reduced after treatment. The remarkable catalytic, thermo-stability and re-cycling features of the agar-agar immobilized MnP display a high potential for biotechnological applications.

Mutagenicity, cytotoxicity and phytotoxicity evaluation of biodegraded textile effluent by fungal ligninolytic enzymes

Colored effluents from the textile industry have led to severe environmental pollution, and this has emerged as a global issue. The feasibility of ligninolytic enzymes for the detoxification and degradation of textile wastewater was investigated. Ganoderma lucidum crude ligninolytic enzymes extract (MnP 717.7, LiP 576.3, and Laccase 323.2 IU/mL) was produced using solid-state culture using wheat bran as substrate. The biodegradation treatment efficiency was evaluated on the basis of degradation and detoxification of textile effluents. Standard bioassays were employed for mutagenicity, cytotoxicity and phytotoxicity evaluation before and after biodegradation. The degradation of Masood Textile, Kalash Textile, Khyber Textile and Sitara Textile effluents was achieved up to 87.29%, 80.17%, 77.31% and 69.04%, respectively. The biochemical oxygen demand, chemical oxygen demand, total suspended solids and total organic carbon were improved considerably as a result of biodegradation of textile effluents, which were beyond the permissible limits established by the National Environmental Quality Standards before treatment. The cytotoxicity (Allium cepa, hemolytic, Daphnia magna and brine shrimp), mutagenicity (Ames TA98 and TA100) and phytotoxicity (Triticum aestivum) tests revealed that biodegradation significantly (P < 0.05) detoxifies the toxic agents in wastewater. Results revealed that biodegradation could possibly be used for remediation of textile effluents. However, detoxification monitoring is crucial and should always be used to evaluate the bio-efficiency of a treatment technique.

Dye decolorization and detoxification potential of Ca-alginate beads immobilized manganese peroxidase

Background

In view of compliance with increasingly stringent environmental legislation, an eco-friendly treatment technology of industrial dyes and effluents is a major environmental challenge in the color industry. In present study, a promising and eco‐friendly entrapment approach was adopted to immobilize purified manganese peroxidase (MnP) produced from an indigenous strain of Ganoderma lucidum IBL-05 on Ca-alginate beads. The immobilized MnP was subsequently used for enhanced decolorization and detoxification of textile reactive dyes).

Results

MnP isolated from solid-state culture of G. lucidum IBL-05, presented highest immobilization yield (83.9 %) using alginate beads prepared at optimized conditions of 4 % (w/v) sodium alginate, 2 % (w/v) Calcium chloride (CaCl₂) and 0.5 mg/ml enzyme concentration. Immobilization of MnP enhanced optimum temperature but caused acidic shift in optimum pH of the enzyme. The immobilized MnP showed optimum activity at pH 4.0 and 60 °C as compared to pH 5.0 and 35 °C for free enzyme. The kinetic parameters K_m and V_max of MnP were significantly improved by immobilization. The enhanced catalytic potential of immobilized MnP led to 87.5 %, 82.1 %, 89.4 %, 95.7 % and 83 % decolorization of Sandal-fix Red C₄BLN, Sandal-fix Turq Blue GWF, Sandal-fix Foron Blue E₂BLN, Sandal-fix Black CKF and Sandal-fix Golden Yellow CRL dyes, respectively. The insolubilized MnP was reusable for 7 repeated cycles in dye color removal. Furthermore, immobilized MnP also caused a significant reduction in biochemical oxygen demand (BOD) (94.61-95.47 %), chemical oxygen demand (COD) (91.18-94.85 %), and total organic carbon (TOC) (89.58-95 %) of aqueous dye solutions.

Conclusions

G. lucidum MnP was immobilized in Ca-alginate beads by entrapment method to improve its practical effectiveness. Ca-alginate bound MnP was catalytically more vigorous, thermo-stable, reusable and worked over wider ranges of pH and temperature as compared to its free counterpart. Results of cytotoxicity like hemolytic and brine shrimp lethality tests suggested that Ca-alginate immobilized MnP may effectively be used for detoxification of dyes and industrial effluents.

Biodegradation of Decabromodiphenyl Ether (BDE-209) by Crude Enzyme Extract from Pseudomonas aeruginosa

The biodegradation effect and mechanism of decabromodiphenyl ether (BDE-209) by crude enzyme extract from Pseudomonas aeruginosa were investigated. The results demonstrated that crude enzyme extract exhibited obviously higher degradation efficiency and shorter biodegradation time than Pseudomonas aeruginosa itself. Under the optimum conditions of pH 9.0, 35 °C and protein content of 2000 mg/L, 92.77% of the initial BDE-209 (20 mg/L) was degraded after 5 h. A BDE-209 biodegradation pathway was proposed on the basis of the biodegradation products identified by GC-MS analysis. The biodegradation mechanism showed that crude enzyme extract degraded BDE-209 into lower brominated PBDEs and OH-PBDEs through debromination and hydroxylation of the aromatic rings.