Aptitude of Oxidative Enzymes for Treatment of Wastewater Pollutants: A Laccase Perspective

Bioremediation of organic pollutants by laccase-metal-organic framework composites: A review of current knowledge and future perspective

Immobilized laccases are widely used as green biocatalysts for bioremediation of phenolic pollutants and wastewater treatment. Metal-organic frameworks (MOFs) show potential application for immobilization of laccase. Their unique adsorption properties provide a synergic effect of adsorption and biodegradation. This review focuses on bioremediation of wastewater pollutants using laccase-MOF composites, and summarizes the current knowledge and future perspective of their biodegradation and the enhancement strategies of enzyme immobilization. Mechanistic strategies of preparation of laccase-MOF composites were mainly investigated via physical adsorption, chemical binding, and de novo/co-precipitation approaches. The influence of architecture of MOFs on the efficiency of immobilization and bioremediation were discussed. Moreover, as sustainable technology, the integration of laccases and MOFs into wastewater treatment processes represents a promising approach to address the challenges posed by industrial pollution. The MOF-laccase composites can be promising and reliable alternative to conventional techniques for the treatment of wastewaters containing pharmaceuticals, dyes, and phenolic compounds. The detailed exploration of various immobilization techniques and the influence of MOF architecture on performance provides valuable insights for optimizing these composites, paving the way for future advancements in environmental biotechnology. The findings of this research have the potential to influence industrial wastewater treatment and promoting cleaner treatment processes and contributing to sustainability efforts.

Elucidating the degradation mechanisms of perfluorooctanoic acid and perfluorooctane sulfonate in various environmental matrices: a review of green degradation pathways

Given environmental persistence, potential for bioaccumulation, and toxicity of Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), the scientific community has increasingly focused on researching their toxicology and degradation methods. This paper presents a survey of recent research advances in the toxicological effects and degradation methods of PFOA and PFOS. Their adverse effects on the liver, nervous system, male reproductive system, genetics, and development are detailed. Additionally, the degradation techniques of PFOA and PFOS, including photochemical, photocatalytic, and electrochemical methods, are analyzed and compared, highlighted the potential of these technologies for environmental remediation. The biotransformation pathways and mechanisms of PFOA and PFOS involving microorganisms, plants, and enzymes are also presented. As the primary green degradation pathway for PFOA and PFOS, Biodegradation uses specific microorganisms, plants or enzymes to remove PFOA and PFOS from the environment through redox reactions, enzyme catalysis and other pathways. Currently, there has been a paucity of research conducted on the biodegradation of PFOA and PFOS. However, this degradation technology is promising owing to its specificity, cost-effectiveness, and ease of implementation. Furthermore, novel materials/methods for PFOA and PFOS degradation are presented in this paper. These novel materials/methods effectively improve the degradation efficiency of PFOA and PFOS and provide new ideas and tools for the degradation of PFOA and PFOS. This information can assist researchers in identifying flaws and gaps in the field, which can facilitate the formulation of innovative research ideas.

Genome-wide analysis of the common bean (Phaseolus vulgaris) laccase gene family and its functions in response to abiotic stress

BACKGROUND

Laccase (LAC) gene family plays a pivotal role in plant lignin biosynthesis and adaptation to various stresses. Limited research has been conducted on laccase genes in common beans.

RESULTS

29 LAC gene family members were identified within the common bean genome, distributed unevenly in 9 chromosomes. These members were divided into 6 distinct subclades by phylogenetic analysis. Further phylogenetic analyses and synteny analyses indicated that considerable gene duplication and loss presented throughout the evolution of the laccase gene family. Purified selection was shown to be the major evolutionary force through Ka / Ks. Transcriptional changes of PvLAC genes under low temperature and salt stress were observed, emphasizing the regulatory function of these genes in such conditions. Regulation by abscisic acid and gibberellins appears to be the case for PvLAC3, PvLAC4, PvLAC7, PvLAC13, PvLAC14, PvLAC18, PvLAC23, and PvLAC26, as indicated by hormone induction experiments. Additionally, the regulation of PvLAC3, PvLAC4, PvLAC7, and PvLAC14 in response to nicosulfuron and low-temperature stress were identified by virus-induced gene silence, which demonstrated inhibition on growth and development in common beans.

CONCLUSIONS

The research provides valuable genetic resources for improving the resistance of common beans to abiotic stresses and enhance the understanding of the functional roles of the LAC gene family.

Enzyme stability in polymer hydrogel-enzyme hybrid nanocarrier containing phosphorylcholine group

Enzymes are biological catalysts with good biocompatibility and high efficiency and have been widely used in many fields, such as wastewater treatment, biosensors, and the medical industry. However, their inherently low stability under conditions of practical use limits further applications. Zwitterionic polymers possessing a pair of oppositely charged groups in their repeating units can increase protein stability because of their good biocompatibility and high water content. In this study, zwitterionic copolymer nanogels comprising poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-methacrylic acid-N-hydroxy succinimide ester (MNHS)) (PMS) were synthesized via reversible addition-fragmentation chain-transfer polymerization (RAFT). β-Galactosidase (β-gal) was post-modified within zwitterionic polymer nanogels with a covalently-bound spacer and the activity was compared with that of directly immobilized β-gal and free β-gal. Compared with direct immobilization, covalent immobilization with a spacer could reduce the structural change of β-gal, as confirmed by the circular dichroism spectra. Although the activity of β-gal decreased after immobilization, the hybrids of the β-gal immobilized nanogels, termed hybrid nanogel-enzymes, demonstrated superior stability compared to the free enzymes. The hybrid nanogel-enzymes maintained their function against inactivation by organic solvents and proteinases owing to their high water content, anti-biofouling properties, and limited mass transfer. They can also withstand protein aggregation at high temperatures and maintain their activity. Compared to direct immobilization, immobilization with a spacer resulted in a dramatic increase in the enzyme activity and a slight decrease in the stability. These results indicate that polymer nanogels containing phosphorylcholine units are promising materials for enzyme immobilization, expanding the scope of enzyme applications.

In silico and in vitro assays suggests Congo red dye degradation by a Lentinus sp. laccase enzyme

Laccase is a superfamily of ligninolytic enzymes known to degrade a wide variety of xenobiotics, including synthetic dyes. Congo Red (CR) has a diazo dye function, carcinogenic and mutagenic potential, and is currently applied in clinical analysis. The objective of this work was to produce and characterize the crude extract of Lentinus sp. in semi-solid fermentation (FSS) and perform in vitro and in silico studies to assess the potential of the crude extract to discolor the CR dye. Laccase activity was determined using ABTS as substrate and characterized. The in vitro discoloration was carried out using experimental design 22 at room temperature and monitored at 340 nm for 24h. Molecular docking and molecular dynamics simulations were performed between laccase and CR. The maximum laccase activity production was 29.63 U L-1 with six days of FSS. The optimal temperature and pH were 50 °C and 3.0, respectively. Discoloration of the CR dye was obtained only in tests containing CuSO4. Laccase formed stable complexes with the dye, presenting negative binding energy values ranging from -70.94 to -63.16 kcal mol-1 and the occurrence of seven hydrogen bonds. Molecular dynamics results showed the stability of the system (RMSD ranging from 1.0 to 2.5 Ä) and protein-ligand interaction along simulation. RMSF values pointed residues at the end of chains A (residues 300 to 305, 480 to 500) and B (residues 650 to 655 and 950 to 1000) as the most flexible regions of the laccase. This study highlighted the enzymatic action in the bioremediation of CR in vitro in agreement with the in silico simulations that demonstrate the enzyme potential.Communicated by Ramaswamy H. Sarma.

Use of sawdust for production of ligninolytic enzymes by white-rot fungi and pharmaceutical removal

Use of white-rot fungi for enzyme-based bioremediation of wastewater is of high interest. These fungi produce considerable amounts of extracellular ligninolytic enzymes during solid-state fermentation on lignocellulosic materials such as straw and sawdust. We used pure sawdust colonized by Pleurotus ostreatus, Trametes versicolor, and Ganoderma lucidum for extraction of ligninolytic enzymes in aqueous suspension. Crude enzyme suspensions of the three fungi, with laccase activity range 12-43 U/L and manganese peroxidase activity range 5-55 U/L, were evaluated for degradation of 11 selected pharmaceuticals spiked at environmentally relevant concentrations. Sulfamethoxazole was removed significantly in all treatments. The crude enzyme suspension from P. ostreatus achieved degradation of wider range of pharmaceuticals when the enzyme activity was increased. Brief homogenization of the colonized sawdust was also observed to be favorable, resulting in significant reductions after a short exposure of 5 min. The highest reduction was observed for sulfamethoxazole which was reduced by 84% compared to an autoclaved control without enzyme activity and for trimethoprim which was reduced by 60%. The compounds metoprolol, lidocaine, and venlafaxine were reduced by approximately 30% compared to the control. Overall, this study confirmed the potential of low-cost lignocellulosic material as a substrate for production of enzymes from white-rot fungi. However, monitoring over time in bioreactors revealed a rapid decrease in enzymatic ligninolytic activity.

Distribution characteristics and transformation mechanism of per- and polyfluoroalkyl substances in drinking water sources: A review

Per- and polyfluoroalkyl substances (PFASs) have raised significant concerns within the realm of drinking water due to their widespread presence in various water sources. This prevalence poses potential risks to human health, ecosystems, and the safety of drinking water. However, there is currently a lack of comprehensive reviews that systematically categorize the distribution characteristics and transformation mechanisms of PFASs in drinking water sources. This review aims to address this gap by concentrating on the specific sources of PFASs contamination in Chinese drinking water supplies. It seeks to elucidate the migration and transformation processes of PFASs within each source, summarize the distribution patterns of PFASs in surface and subsurface drinking water sources, and analyze how PFASs molecular structure, solubility, and sediment physicochemical parameters influence their presence in both the water phase and sediment. Furthermore, this review assesses two natural pathways for PFASs degradation, namely photolysis and biodegradation. It places particular emphasis on understanding the degradation mechanisms and the factors that affect the breakdown of PFASs by microorganisms. The ultimate goal is to provide valuable insights for the prevention and control of PFAS contamination and the assurance of drinking water quality.

Fabrication and performance analysis of keratin based-graphene oxide nanocomposite to remove dye from tannery wastewater

In recent years, nanomaterials and composites have become increasingly significant as adsorbents in the removal of dyes and phenolic contaminants from wastewater. This study presents the development and application of a keratin-based graphene oxide nanocomposite, distinguished by its enhanced biocompatibility, cost-effectiveness, and strong affinity for organic compounds, making it highly effective in reducing dyes within tannery effluent. The nanocomposite was prepared via solution casting method, with dispersibility, chemical bonding, and morphology analyzed by UV-Vis spectroscopy, FTIR, and SEM, respectively. Furthermore, investigations of the influence of several factors, such as contact time, pH, and adsorbent dosage on the optimization of the process were conducted. An observation indicated a reduction of approximately 98.8 % in dye content within 20 min, achieved through the use of an adsorbent dosage of 1.5 g/L, with the solution pH maintained at 5. Subsequently, adsorption kinetics and isotherm modelling were analyzed. The results revealed that the adsorption process follows the pseudo-second-order kinetics and Freundlich isotherm models. Hence, the adsorption could be explained as chemisorption with a multilayer adsorption mechanism. Notably, a substantial reduction in parameters such as Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) was also achieved up to 62 % and 79 %, respectively. Therefore, the developed adsorbent could be suggested as a viable candidate for eliminating dyes from the wastewater, especially from the tannery effluent.

Agitation role (Dissolved Oxygen) in production of laccase from newly identified Ganoderma multistipitatum sp. nov. and its effect on mycelium morphology

BACKGROUND

Agitation speed influenced the production rate of laccase. Orbital speed not only influenced the enzyme production, but was also effective to dissolve the oxygen during growth of mycelium, spores, and chlamydospores. Shear effects of speed greatly influenced the morphology of mycelium.

METHODS

Ganoderma multistipitatum was identified by ITS marker. Phylogenetic tree was constructed for species identification. Qualitatively by plate method contained guaiacol indicator, while quantitatively by submerged fermentation and Central Composite Design applied on agitation parameter for maximum laccase potential of this species. The effects of agitation speed on mycelium morphology were observed under compound and scanning electron microscope.

RESULTS

Statistical optimization of agitation conditions were performed by using response surface methodology to enhance the production of laccase from Ganoderma multistipitatum sp. nov. Maximum laccase yield (19.44 × 105 ± 0.28 U/L) was obtained at 150 rpm grown culture, which was higher than predicted value of laccase production (19.18 × 105 U/L) under aerobic conditions (150 rpm). The 150 rpm provided the continuous flush of oxygen. The DO (dissolved oxygen) was maximum (65%) for "27 h" incubation at 150 rpm during laccase synthesis. The statistical value of laccase production was minimum under anaerobic or nearly static condition of 50 rpm. The predicted (12.78 × 105 U/L) and obtained (12.82 × 105 U/L) yield was low at 50 rpm. Optimization of orbital shaking for aeration conditions were performed by the use of "Response Surface Methodology". The submerged shaking flasks were utilized as a nutrients growth medium to maximize the production of laccase from G. multistipitatum. The minimum incubation time highly influenced the laccase yield from 7 to 15 days via utilization of less cost-effective medium under a promising and eco-friendly method. The morphological effects of rpm on mycelium were examined under compound and scanning electron microscopy. Higher rpm (200, 230) shear the mycelium, while 150 to 200 rpm exhibited smoother and highly dense branches of mycelia.

CONCLUSION

The shear forces of 200 rpm caused the damages of mycelium and cells autolysis with less laccase production. This study concluded that 150 rpm saved the life of mycelium and enhanced the production rate of enzymes.

Recent Advances in Applications of Oxidases and Peroxidases Polymer-Based Enzyme Biocatalysts in Sensing and Wastewater Treatment: A Review

Oxidase and peroxidase enzymes have attracted attention in various biotechnological industries due to their ease of synthesis, wide range of applications, and operation under mild conditions. Their applicability, however, is limited by their poor stability in harsher conditions and their non-reusability. As a result, several approaches such as enzyme engineering, medium engineering, and enzyme immobilization have been used to improve the enzyme properties. Several materials have been used as supports for these enzymes to increase their stability and reusability. This review focusses on the immobilization of oxidase and peroxidase enzymes on metal and metal oxide nanoparticle-polymer composite supports and the different methods used to achieve the immobilization. The application of the enzyme-metal/metal oxide-polymer biocatalysts in biosensing of hydrogen peroxide, glucose, pesticides, and herbicides as well as blood components such as cholesterol, urea, dopamine, and xanthine have been extensively reviewed. The application of the biocatalysts in wastewater treatment through degradation of dyes, pesticides, and other organic compounds has also been discussed.

A review of hybrid enzymatic-chemical treatment for wastewater containing antiepileptic drugs

Epilepsy is one of the most common neurological diseases worldwide and requires treatment with antiepileptic drugs for many years or for life. This fact leads to the need for constant production and use of these compounds, placing them among the four pharmaceutical classes most found in wastewater. Even at low concentrations, antiepileptics pose risks to human and environmental health and are considered organic contaminants of emerging concern. Conventional treatments have shown low removal of these drugs, requiring advanced and innovative approaches. In this context, this review covers the results and perspectives on (1) consumption and occurrence of antiepileptics in water, (2) toxicological effects in aquatic ecosystems, (3) enzymatic and advanced oxidation processes for degrading antiepileptics drugs from a molecular point of view (biochemical and chemical phenomena), (4) improvements in treatment efficiency by hybridization, and (5) technical aspects of the enzymatic-AOP reactors.

A Review: Per- and Polyfluoroalkyl Substances-Biological Degradation

Per- and polyfluoroalkyl substances (PFASs), highly stable synthetic organic compounds with multiple carbon-fluorine bonds, are emerging as environmental contaminants, toxic, bioaccumulative, and environmentally persistent. PFASs are strongly resistant to biological and chemical degradation, and therefore PFASs present a challenge to researchers and scientists for a better understanding and application of remediation methods and biodegradation of PFASs and have become subject to strict government regulations. The review summarizes the recent knowledge of bacterial and fungal degradation of PFASs, as well as the enzymes involved in the processes of transformation/degradation of PFASs.

Identification of laccase genes in Trichoderma asperellum Ts93

Although extensive research efforts have been dedicated to characterizing the laccase from white-rot fungus, little information is available on laccases from Trichoderma spp. A copper-tolerant strain with the ability to produce laccase was isolated and identified as Trichoderma asperellum Ts93. Under optimized conditions, the maximum laccase activity was 1.96 U/ml. The genome-wide survey of Ts93 revealed the presence of seven putative laccase genes that all contained the conserved domain and were divided into three different phylogenetic groups. Among these genes, three contained the four copper-binding conserved regions. The expression profiles acquired through real-time quantitative PCR analysis showed that five of the seven genes were significantly upregulated in response to laccase activity. Seven laccase genes in T. asperellum were identified for the first time by whole-genome sequencing followed by phylogenetic analysis. The findings of this work provide valuable information for the functional analysis of laccase genes in Trichoderma spp.

A novel promising laccase from the psychrotolerant and halotolerant Antarctic marine Halomonas sp. M68 strain

Microbial communities inhabiting the Antarctic Ocean show psychrophilic and halophilic adaptations conferring interesting properties to the enzymes they produce, which could be exploited in biotechnology and bioremediation processes. Use of cold- and salt-tolerant enzymes allows to limit costs, reduce contaminations, and minimize pretreatment steps. Here, we report on the screening of 186 morphologically diverse microorganisms isolated from marine biofilms and water samples collected in Terra Nova Bay (Ross Sea, Antarctica) for the identification of new laccase activities. After primary screening, 13.4 and 10.8% of the isolates were identified for the ability to oxidize 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and the dye azure B, respectively. Amongst them, the marine Halomonas sp. strain M68 showed the highest activity. Production of its laccase-like activity increased six-fold when copper was added to culture medium. Enzymatic activity-guided separation coupled with mass spectrometry identified this intracellular laccase-like protein (named Ant laccase) as belonging to the copper resistance system multicopper oxidase family. Ant laccase oxidized ABTS and 2,6-dimethoxy phenol, working better at acidic pHs The enzyme showed a good thermostability, with optimal temperature in the 40-50°C range and maintaining more than 40% of its maximal activity even at 10°C. Furthermore, Ant laccase was salt- and organic solvent-tolerant, paving the way for its use in harsh conditions. To our knowledge, this is the first report concerning the characterization of a thermo- and halo-tolerant laccase isolated from a marine Antarctic bacterium.

Applications and immobilization strategies of the copper-centred laccase enzyme; a review

Laccase is a multi-copper enzyme widely expressed in fungi, higher plants, and bacteria which facilitates the direct reduction of molecular oxygen to water (without hydrogen peroxide production) accompanied by the oxidation of an electron donor. Laccase has attracted attention in biotechnological applications due to its non-specificity and use of molecular oxygen as secondary substrate. This review discusses different applications of laccase in various sectors of food, paper and pulp, waste water treatment, pharmaceuticals, sensors, and fuel cells. Despite the many advantages of laccase, challenges such as high cost due to its non-reusability, instability in harsh environmental conditions, and proteolysis are often encountered in its application. One of the approaches used to minimize these challenges is immobilization. The various methods used to immobilize laccase and the different supports used are further extensively discussed in this review.

Genome-wide analysis of the Populus trichocarpa laccase gene family and functional identification of PtrLAC23

INTRODUCTION

Biofuel is a kind of sustainable, renewable and environment friendly energy. Lignocellulose from the stems of woody plants is the main raw material for "second generation biofuels". Lignin content limits fermentation yield and is therefore a major obstacle in biofuel production. Plant laccase plays an important role in the final step of lignin formation, which provides a new strategy for us to obtain ideal biofuels by regulating the expression of laccase genes to directly gain the desired lignin content or change the composition of lignin.

METHODS

Multiple sequence alignment and phylogenetic analysis were used to classify PtrLAC genes; sequence features of PtrLACs were revealed by gene structure and motif composition analysis; gene duplication, interspecific collinearity and Ka/Ks analysis were conducted to identify ancient PtrLACs; expression levels of PtrLAC genes were measured by RNA-Seq data and qRT-PCR; domain analysis combine with cis-acting elements prediction together showed the potential function of PtrLACs. Furthermore, Alphafold2 was used to simulate laccase 3D structures, proLAC23::LAC23-eGFP transgenic Populus stem transects were applied to fluorescence observation.

RESULTS

A comprehensive analysis of the P. trichocarpa laccase gene (PtLAC) family was performed. Some ancient PtrLAC genes such as PtrLAC25, PtrLAC19 and PtrLAC41 were identified. Gene structure and distribution of conserved motifs clearly showed sequence characteristics of each PtrLAC. Combining published RNA-Seq data and qRT-PCR analysis, we revealed the expression pattern of PtrLAC gene family. Prediction results of cis-acting elements show that PtrLAC gene regulation was closely related to light. Through above analyses, we selected 5 laccases and used Alphafold2 to simulate protein 3D structures, results showed that PtrLAC23 may be closely related to the lignification. Fluorescence observation of proLAC23::LAC23-eGFP transgenic Populus stem transects and qRT-PCR results confirmed our hypothesis again.

DISCUSSION

In this study, we fully analyzed the Populus trichocarpa laccase gene family and identified key laccase genes related to lignification. These findings not only provide new insights into the characteristics and functions of Populus laccase, but also give a new understanding of the broad prospects of plant laccase in lignocellulosic biofuel production.

Efficient Azo Dye Biodecolorization System Using Lignin-Co-Cultured White-Rot Fungus

The extensive use of azo dyes by the global textile industry induces significant environmental and human health hazards, which makes efficient remediation crucial but also challenging. Improving dye removal efficiency will benefit the development of bioremediation techniques for textile effluents. In this study, an efficient system for azo dye (Direct Red 5B, DR5B) biodecolorization is reported, which uses the white-rot fungus Ganoderma lucidum EN2 and alkali lignin. This study suggests that the decolorization of DR5B could be effectively enhanced (from 40.34% to 95.16%) within 48 h in the presence of alkali lignin. The dye adsorption test further confirmed that the alkali-lignin-enhanced decolorization of DR5B was essentially due to biodegradation rather than physical adsorption, evaluating the role of alkali lignin in the dye biodegradation system. Moreover, the gas chromatography/mass spectrometry analysis and DR5B decolorization experiments also indicated that alkali lignin carried an excellent potential for promoting dye decolorization and displayed a significant role in improving the activity of lignin-modifying enzymes. This was mainly because of the laccase-mediator system, which was established by the induced laccase activity and lignin-derived small aromatic compounds.

Design of biomass-based renewable materials for environmental remediation

Various materials have been used to remove environmental contaminants for decades and have been an effective strategy for environmental cleanups. The current nonrenewable materials used for this purpose could impose secondary hazards and challenges in further downstream treatments. Biomass-based materials present viable, renewable, and sustainable solutions for environmental remediation. Recent biotechnology advances have developed biomaterials with new capacities, such as highly efficient biodegradation and treatment train integration. This review systemically discusses how biotechnology has empowered biomass-derived and bioinspired materials for environmental remediation sustainably and cost-effectively.

Microbial degradation and transformation of benzo[a]pyrene by using a white-rot fungus Pleurotus eryngii F032

Polycyclic aromatic hydrocarbons (PAHs) are environmentally recalcitrant contaminants formed from naturally or incomplete combustion of organic materials and some of them are difficult to degrade due to their hydrophobicity and persistency. Benzo [a]pyrene (BaP), is one of PAHs that having five fused benzene and reported as mutagenic, carcinogenic and teratogenic compounds. Biodegradation is one of promising techniques due to its relatively low economic cost and microorganism is a natural capacity to consume hydrocarbons. In this investigation, Pleurotus eryngii F032 was grown in 20 mL of modified mineral salt broth (MSB) supplemented with BaP under static and agitated culture. Within 20 days, static culture removed 59% of BaP, whereas agitated culture removed the highest amount (73%). To expedite BaP elimination, the mechanism and behavior of BaP biosorption and biotransformation by Pleurotus eryngii F032 were additionally examined by gas chromatography-mass spectrometer (GC-MS). The optimal conditions for P. eryngii F032 to eliminate BaP were 25 °C, a C/N ratio of 8, pH 3 and 0.2% inoculum concentration. At an initial BaP content of 10 mg/L, more than 50% was effectively eliminated within 20 days under these conditions. Salinity, glucose, and rhamnolipids were the most important factors impacting BaP biodegradation. GC-MS found degradation products such as BaP-3,6-quinone, indicating plausible metabolic routes. Finally, it may be assumed that the primary mechanism by which white-rot fungi eliminate BaP is by the utilization of biotransformation enzymes such as laccase to mineralize the PAHs. Hence, Pleurotus eryngii F032 could be an ideal candidate to treat PAHs contaminated soils.

Novel bio-catalytic degradation of endocrine disrupting compounds in wastewater

Against the backdrop of towering ecological health implications of estrogen pollution and the inefficacies associated with cost-intensive treatment techniques, this study recorded the earliest attempt of developing an inexpensive bacterial laccase-based biocatalysts for biodegradation of EDCs (Endocrine disrupting compounds), particularly estrogens. First, a central composite design was used to investigate the interactive effects of pH (6.0–8.0), inoculum size (100–500 U/mL), and copper (Cu) (25–75 mg/L) on laccase activity and estrogen degradation respectively. Thereafter, biocatalysts was synthesized comprising laccase and glass beads or silver impregnated clay granules (SICG), which was further used to treat estrogen infused aquatic matrices under different reaction conditions. Maximum laccase activities and estrogen removal for the two tested laccases were 620 U/mL (85.8–92.9%) and 689.8 U/mL (86.8–94.6%) for Lysinibacillus sp. BP1 and Lysinibacillus sp. BP2, respectively, within 72 h, under conditions of optimal inoculum size and/or Cu concentration. Apart from a higher estrogen removal rate compared to free laccased, the biocatalysts were more resistant to temperature, pH and other environmental perturbations, and had enhanced storage ability and reusability. In comparison to clay, beads had a higher potential for recyclability and were more stable under certain experimental factors such as pH, reuse, and temperature, as well as storage conditions. Immobilized enzymes were able to remove 100% of E2, as well as over 90% of E1 and EE2, in 24 h, indicating that they could be scaled up to benchtop bioreactor levels.

Microaerobic conditions enhance laccase production from Rheinheimera sp. in an economical medium

Statistical optimization of aeration conditions viz. aerobic, microaerobic and anaerobic, was performed using response surface methodology (RSM) utilizing soybean meal as medium to enhance the production of laccase from Rheinheimera sp. Maximum laccase yield (18.48 × 10⁵ U/L) was obtained under microaerobic (static) conditions sustained for 12 h in tandem with 26 h aerobically (150 rpm) grown culture, which was 17.03-fold higher than laccase production in the starting M162 medium under aerobic conditions (150 rpm). The reduction in incubation time from 72 to 38 h and utilization of cost-effective soybean meal as medium, which is easily available from local market, have provided a promising, eco-friendly method of laccase enzyme production. Enhanced expression of laccase gene under microaerobic conditions corresponded to the increased expression of fnr (fumarate nitrate reductase) gene, the oxygen sensing global regulator. The putative FNR-binding site upstream of laccase transcription initiation site was predicted to play an imperative role in Rheinheimera sp. adaptation from aerobic to microaerobic conditions and for enhanced laccase production.

Hormetic effect of 17α-ethynylestradiol on activated sludge microbial community response

Synthetic estrogen analogues are among the most potent estrogenic contaminants in effluents from wastewater treatment plants. Although its effects have been well elucidated in the feminization of male fish and interference with the endocrine systems in humans, it has not been fully explored in the activated sludge (AS) microbiome, particularly EE2 (17α-ethynylestradiol). Therefore, in this study, the bacterial community shift in a 6-day laboratory-scale reactor in environmental (0, 5, 10, and 100 ng/L) and predictive elevated concentrations (5, 10, and 100 mg/L) of EE2 was investigated using culture-based and metagenomics approaches. Results showed significant changes (t-test, all p < 0.05) between initial and final physicochemical parameters (pH, DO, and EC). Although environmental concentrations showed a slight decrease in microbial counts (5.6 × 10⁶ to 4.6 × 10⁶ CFU/ml) after a 24-h incubation for the culturable approach, the predictive elevated concentrations (5 to 100 mg/L) revealed a drastic microbial counts reduction (5.6 × 10⁶ to 8 × 10² CFU/ml). The metagenomic data analysis uncovered that bacterial communities in the control sample were dominated by Proteobacteria, followed by Bacteroidetes and Firmicutes. The taxonomic classification after exposure of microbial communities in various concentrations revealed significant differences in community composition between environmental concentration (Shannon indices between 2.58 to 3.68) and predictive elevated concentrations (Shannon indices between 2.24 and 2.84; t-test, all p < 0.05). The EE2 enriched seven OTUs were Novosphingobium, Cloacibacterium, Stenotrophomonas, Enterobacteriaceae_unclassified, Stenotrophomonas, Enterobacteriaceae_unclassified and Rhodobacteraceae_unclassified. These results were supported by a dehydrogenase activity (DHA) test, which demonstrated less (about 40%) DHA in predictive elevated concentrations than in environmental concentrations. Notwithstanding, these findings suggest that EE2 may possess potent hormetic effect as evidenced by promotion of microbiome richness and dehydrogenase activity of AS in lower EE2 doses.

Novel Magnetic Polymeric Filters with Laccase-Based Nanoparticles for Improving Congo Red Decolorization in Bioreactors

In this work, five different magnetic biofilters, containing magnetic nanoparticles (142 nm), immobilized laccase on nanoparticles (190 nm) and permanent magnetic elements, such as neodymium magnets and metallic meshes, were designed, manufactured and tested. The five types of filters were compared by measuring the decolorization of Congo Red dye inside bioreactors, the half-life of the filters and the amount of magnetic nanoparticle and enzyme lost during multiple cycles of operation. Filters containing laccase immobilized on magnetite (Laccase-magnetite), permanent magnets and metallic mesh presented the highest Congo Red decolorization (27%) and the largest half-life among all types of filters (seven cycles). The overall dye decolorization efficiencies were 5%, 13%, 17%, 23%, and 27% for the paper filter, paper filter with magnetite, paper filter with Laccase-magnetite, paper filter with Laccase-magnetite with magnets and paper filter with Laccase-magnetite with magnets and metallic mesh, respectively. Although the highest losses of magnetite occurred when using the filters containing magnets (57 mg), the use of permanent magnetic elements in the filters increased the half-life of the filter three-fold compared to the filters without enzymatic properties and two-fold compared to the filters with Laccase-magnetite. Results indicate that the novel use of permanent magnetic elements improved the nanoparticle retention in the filters and promoted the mass transfer between the dye and the biocatalyst to enhance wastewater treatment.

Advances on removal of organophosphorus pesticides with electrochemical technology

Widespread use of organophosphorus pesticides (OPs), especially superfluous and unreasonable use, had brought huge harm to the environment and food chain. It is because only a small part of the pesticides sprayed reached the target, and the rest slid across the soil, causing pollution of groundwater and surface water resources. These pesticides accumulate in the environment, causing environmental pollution. Therefore, in recent years, the control and degradation of OPs have become a public spotlight and research hotspot. Due to its unique advantages such as versatility, environmental compatibility, controllability, and cost-effectiveness compatibility, electrochemical technology has become one of the most promising methods for degradation of OPs. The fundamental knowledge about electrochemical degradation on OPs was introduced in this review. Then, a comprehensive overview of four main types of practical electrochemical technologies to degrade pesticides were presented and evaluated. The knowledge contained herein should conduce to better understand the degradation of pesticides by electrochemical technology, and better exploit the degradation of pesticides in the environment and food. Overall, the objective of this review is to provide comprehensive guidance for rational design and application of electrochemical technology in the degradation of OPs for the safety of the environment and food chain in the future.

Highly efficient removal of dyes from wastewater using nanocellulose from quinoa husk as a carrier for immobilization of laccase

In this study, the synthesis of nanocellulose (NC) from an agro-waste of quinoa husks (QS) was reported for the first time. The NC nano-carrier was utilized for immobilization of a model laccase enzyme (PersiLac1) providing an innovative, green, and practical nano-biocatalyst for efficient removal of two different model dyes (malachite green (MG) and congo red (CR)) from water. This nano-biocatalyst developed a synergistic adsorption-degradation approach leading the dye molecules easily gathered near the nano-carrier by adsorption and then degraded effectively by the enzyme. Upon enzyme immobilization, the dye removals (%) were remarkably improved for both 150 mg/L of dyes (from 54% and 12%, for MG and CR, respectively, in case of the pristine NCs, to 98% and 60% for the immobilized enzyme). The immobilized PersiLac1 could decolorize the concentrated dye solutions and showed superior reusability (up to 83% dye removal after 18th runs for MG) and remarkable performance from complex real textile effluents.

Microbial approaches for sustainable remediation of dye-contaminated wastewater: a review

The coloured effluents produced from different industries, such as textile, plastics, printing, cosmetics, leather and paper, are extremely toxic and a tremendous threat to the aquatic organisms and human beings. The removal of coloured dye pollutants from the aqueous environment is a great challenge and a pressing task. The growing demand for low-cost and efficient treatment approaches has given rise to alternative and eco-friendly methods, such as biodegradation and microbial remediation. This work summarizes the overview and current research on the remediation of dye pollutants from the aqueous environment by microbial bio-sorbents, such as bacteria, fungi, algae, and yeast. In addition, dye degradation capabilities of microbial enzymes have been highlighted and discussed. Further, the influence of various experimental parameters, such as temperature, pH, and concentrations of nutrients, and dye, has been summarized. The proposed mechanism for dye removal by microorganisms is also discussed. The object of this review is to provide a state-of-the-art of microbial remediation technologies in eliminating dye pollutants from water resources.

Toward Characterizing the Genetic Basis of Trace Organic Contaminant Biotransformation in Activated Sludge: The Role of Multicopper Oxidases as a Case Study

Activated sludge treatment leverages the ability of microbes to uptake and (co)-metabolize chemicals and has shown promise in eliminating trace organic contaminants (TrOCs) during wastewater treatment. However, targeted interventions to optimize the process are limited as the fundamental drivers of the observed reactions remain elusive. In this work, we present a comprehensive workflow for the identification and characterization of key enzymes involved in TrOCs biotransformation pathways in complex microbial communities. To demonstrate the applicability of the workflow, we investigated the role of the enzymatic group of multicopper oxidases (MCOs) as one putatively relevant driver of TrOCs biotransformation. To this end, we analyzed activated sludge metatranscriptomic data and selected, synthesized, and heterologously expressed three phylogenetically distinct MCO-encoding genes expressed in communities with different TrOCs oxidation potentials. Following the purification of the encoded enzymes, we screened their activities against different substrates. We saw that MCOs exhibit significant activities against selected TrOCs in the presence of the mediator compound 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid and, in some cases, also in the presence of the wastewater contaminant 4'-hydroxy-benzotriazole. In the first case, we identified oxidation products previously reported from activated sludge communities and concluded that in the presence of appropriate mediators, bacterial MCOs could contribute to the biological removal of TrOCs. Similar investigations of other key enzyme systems may significantly advance our understanding of TrOCs biodegradation and assist the rational design of biology-based water treatment strategies in the future.

Biocatalytic membranes for combating the challenges of membrane fouling and micropollutants in water purification: A review

Over the last few years, the list of water contaminants has grown tremendously due to many anthropogenic activities. Various conventional technologies are available for water and wastewater treatment. However, micropollutants of emerging concern (MEC) are posing a great threat due to their activity at trace concentration and poor removal efficiency by the conventional treatment processes. Advanced technology like membrane technology can remove MEC to some extent. However, issues like the different chemical properties of MEC, selectivity, and fouling of membranes can affect the removal efficiency. Moreover, the concentrate from the membrane filtration may need further treatment. Enzymatic degradation of pollutants and foulants is one of the green approaches for removing various contaminants from the water as well as mitigating membrane fouling. Biocatalytic membranes (BCMs), in which enzymes are immobilized on membranes, combines the advantages of membrane separation and enzymatic degradation. This review article discussed various commonly used enzymes in BCMs for removing MEC and fouling. The majorly used enzymes were oxidoreductases and hydrolases for removing MEC, antifouling, and self-cleaning ability. The various BCM synthesis processes based on entrapment, crosslinking, and binding have been summarized, along with the effects of the addition of the nanoparticles on the performances of the BCMs. The scale-up, commercial viability, challenges, and future direction for improving BCMs have been discussed and shown bright possibilities for these new generation membranes.

Recent Developments in the Immobilization of Laccase on Carbonaceous Supports for Environmental Applications - A Critical Review

Τhe ligninolytic enzyme laccase has proved its potential for environmental applications. However, there is no documented industrial application of free laccase due to low stability, poor reusability, and high costs. Immobilization has been considered as a powerful technique to enhance laccase's industrial potential. In this technology, appropriate support selection for laccase immobilization is a crucial step since the support could broadly affect the properties of the resulting catalyst system. Through the last decades, a large variety of inorganic, organic, and composite materials have been used in laccase immobilization. Among them, carbon-based materials have been explored as a support candidate for immobilization, due to their properties such as high porosity, high surface area, the existence of functional groups, and their highly aromatic structure. Carbon-based materials have also been used in culture media as supports, sources of nutrients, and inducers, for laccase production. This study aims to review the recent trends in laccase production, immobilization techniques, and essential support properties for enzyme immobilization. More specifically, this review analyzes and presents the significant benefits of carbon-based materials for their key role in laccase production and immobilization.

Novel Thermophilic Bacterial Laccase for the Degradation of Aromatic Organic Pollutants

We identified a putative laccase from the thermophilic bacterium Geobacillus yumthangensis. The putative laccase was produced recombinantly and its ability to catalyse the degradation of aromatic organic pollutants was investigated. The putative laccase exhibits broad pH and temperature stability, and, notably, it could catalyse the degradation of organic dyes as well as toxic pollutants including bisphenol A, guaiacol and phenol with a redox mediator. Our work further demonstrates the potential of using oxidative enzymes to break down toxic chemicals that possess major threats to human health and the environment.

Treatment of triclosan through enhanced microbial biodegradation

Triclosan (TCS) is extensively used in healthcare and personal care products as an antibacterial agent. Due to the persistent and toxic nature of TCS, it is not completely degraded in the biological wastewater treatment process. In this research work, identification of TCS degrading bacteria from municipal wastewater sludge and applying the same as bioaugmentation treatment for wastewater have been reported. Based on the 16S rRNA analysis of wastewater sludge, it was found that Providencia rettgeri MB-IIT strain was active and able to grow in higher TCS concentration. The identified bacterial strain was able to use TCS as carbon and energy source for its growth. The biodegradation experiment was optimized for the operational parameters viz. pH (5-10), inoculum size (1-5% (v/v)) and different initial concentration (2, 5, and 10 mg/L) of TCS. During the TCS degradation process, manganese peroxidase (MnP) and laccase (LAC) enzyme activity and specific growth rate of P. rettgeri strain were maximum at pH=7% and 2% (v/v) inoculum size, resulting in 98% of TCS removal efficiency. A total of six intermediate products were identified from the Liquid chromatography-high-resolution mass spectrometry (LC-HRMS) analysis, and the two mechanisms responsible for the degradation of TCS have been elucidated. The study highlights that P. rettgeri MB-IIT strain could be advantageously used to degrade triclosan present in the wastewater.

Applications of Biocatalysts for Sustainable Oxidation of Phenolic Pollutants: A Review

Phenol and its derivatives are hazardous, teratogenic and mutagenic, and have gained significant attention in recent years due to their high toxicity even at low concentrations. Phenolic compounds appear in petroleum refinery wastewater from several sources, such as the neutralized spent caustic waste streams, the tank water drain, the desalter effluent and the production unit. Therefore, effective treatments of such wastewaters are crucial. Conventional techniques used to treat these wastewaters pose several drawbacks, such as incomplete or low efficient removal of phenols. Recently, biocatalysts have attracted much attention for the sustainable and effective removal of toxic chemicals like phenols from wastewaters. The advantages of biocatalytic processes over the conventional treatment methods are their ability to operate over a wide range of operating conditions, low consumption of oxidants, simpler process control, and no delays or shock loading effects associated with the start-up/shutdown of the plant. Among different biocatalysts, oxidoreductases (i.e., tyrosinase, laccase and horseradish peroxidase) are known as green catalysts with massive potentialities to sustainably tackle phenolic contaminants of high concerns. Such enzymes mainly catalyze the o-hydroxylation of a broad spectrum of environmentally related contaminants into their corresponding o-diphenols. This review covers the latest advancement regarding the exploitation of these enzymes for sustainable oxidation of phenolic compounds in wastewater, and suggests a way forward.

Enzyme polymer engineered structure strategy to enhance cross-linked enzyme aggregate stability: a step forward in laccase exploitation for cannabidiol removal from wastewater

Despite all its advantages and potential, cross-linking enzyme aggregate (CLEA) technology is still not applied at an industrial scale for enzyme insolubilization for bioremediation purposes. In this study, the enzyme polymer engineered structure (EPES) method was used to enhance CLEA stability and reuse. A crude laccase from Trametes hirsuta was successfully insolubilized to form EPES-CLEAs. The polymeric network provided excellent stability (> 90%) to CLEAs after a 24-h incubation in a non-buffered municipal wastewater effluent (WW), and the biocatalysts were recycled using a centrifugation process. While CLEAs activity dropped to 17%, EPES-CLEAs showed a laccase activity retention of 67% after five cycles of 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) oxidation. After 8 h of treatment in WW, the EPES-CLEAs were equally as effective in removing cannabidiol (CBD) as the free-LAC (~ 37%). This research demonstrates that the EPES method is a promising alternative for CLEA stabilization and reuse in environmental conditions.

A Brief History of Colour, the Environmental Impact of Synthetic Dyes and Removal by Using Laccases

The history of colour is fascinating from a social and artistic viewpoint because it shows the way; use; and importance acquired. The use of colours date back to the Stone Age (the first news of cave paintings); colour has contributed to the social and symbolic development of civilizations. Colour has been associated with hierarchy; power and leadership in some of them. The advent of synthetic dyes has revolutionized the colour industry; and due to their low cost; their use has spread to different industrial sectors. Although the percentage of coloured wastewater discharged by the textile; food; pharmaceutical; cosmetic; and paper industries; among other productive areas; are unknown; the toxic effect and ecological implications of this discharged into water bodies are harmful. This review briefly shows the social and artistic history surrounding the discovery and use of natural and synthetic dyes. We summarise the environmental impact caused by the discharge of untreated or poorly treated coloured wastewater to water bodies; which has led to physical; chemical and biological treatments to reduce the colour units so as important physicochemical parameters. We also focus on laccase utility (EC 1.10.3.2), for discolouration enzymatic treatment of coloured wastewater, before its discharge into water bodies. Laccases (p-diphenol: oxidoreductase dioxide) are multicopper oxidoreductase enzymes widely distributed in plants, insects, bacteria, and fungi. Fungal laccases have employed for wastewater colour removal due to their high redox potential. This review includes an analysis of the stability of laccases, the factors that influence production at high scales to achieve discolouration of high volumes of contaminated wastewater, the biotechnological impact of laccases, and the degradation routes that some dyes may follow when using the laccase for colour removal.

Immobilized Soybean Peroxidase Hybrid Biocatalysts for Efficient Degradation of Various Emerging Pollutants

In the present study, soybean peroxidase (SBP) was covalently immobilized onto two functionalized photocatalytic supports (TiO2 and ZnO) to create novel hybrid biocatalysts (TiO2-SBP and ZnO-SBP). Immobilization caused a slight shift in the pH optima of SBP activity (pH 5.0 to 4.0), whereas the free and TiO2-immobilized SBP showed similar thermal stability profiles. The newly developed hybrid biocatalysts were used for the degradation of 21 emerging pollutants in the presence and absence of 1-hydroxy benzotriazole (HOBT) as a redox mediator. Notably, all the tested pollutants were not equally degraded by the SBP treatment and some of the tested pollutants were either partially degraded or appeared to be recalcitrant to enzymatic degradation. The presence of HOBT enhanced the degradation of the pollutants, while it also inhibited the degradation of some contaminants. Interestingly, TiO2 and ZnO-immobilized SBP displayed better degradation efficiency of a few emerging pollutants than the free enzyme. Furthermore, a combined enzyme-chemical oxidation remediation strategy was employed to degrade two recalcitrant pollutants, which suggest a novel application of these novel hybrid peroxidase-photocatalysts. Lastly, the reusability profile indicated that the TiO2-SBP hybrid biocatalyst retained up to 95% degradation efficiency of a model pollutant (2-mercaptobenzothiazole) after four consecutive degradation cycles.

Fungal laccase-triggered 17β-estradiol humification kinetics and mechanisms in the presence of humic precursors

Naturally-occurring phenolic acids (PAs) act as humic precursors that participate in the conversion behaviors and coupling pathways of steroidal estrogens (SEs) during laccase-triggered humification processes (L-THPs). Herein, the influences and mechanisms of PAs on Trametes versicolor laccase-evoked 17β-estradiol (E2) conversion kinetics and humification routes were explored. Fungal laccase was fleet in converting > 99% of E2, and the calculated pseudo-first-order velocity constant and half-time values were respectively 0.039 min^-1 and 17.906 min. PAs containing an O-dihydroxy moiety such as gallic acid and caffeic acid evidently hampered E2 humification owning to the yielded highly reactive O-quinones reversed E2 radicals by hydrogen transfer mechanism, implying that the inhibition effect was enormously dependent upon the number and position of the phenolic -OH present in humic precursors. Oligomers and polymers with carbon-carbon/oxygen links were tentatively found as E2 main humified species resulting from laccase-evoked successive oxidative-coupling. Note that PAs participating in the humification also encountered oxydehydrogenation, self-polymerization, and cross-binding to E2. Interestingly, the -COOH and -OCH₃ groups of PAs could be deprived in radical-caused self/co-polymerization. The generation of humified products not only circumvented the environmental risks of parent compounds but accelerated global carbon sequestration. To our knowledge, this is the first in-depth revelation of the humification pathways and related mechanisms of SEs with humic precursors in aquatic ecosystems by L-THPs.

Evaluation of Laccase Activities by Three Newly Isolated Fungal Species in Submerged Fermentation With Single or Mixed Lignocellulosic Wastes

Three newly isolated fungal species, namely, Cerrena unicolor Han 849, Lenzites betulina Han 851, and Schizophyllum commune Han 881, isolated from their native habitats in Wulingshan National Nature Reserve of Hebei Province of northern China, were screened for laccase production with single or mixed lignocellulosic wastes. C. unicolor Han 849 was found to express the highest levels of laccase with single or mixed lignocellulosic wastes compared with L. betulina Han 851 and S. commune Han 881. The highest laccase activity from the mixed fungal culture of C. unicolor Han 849 and S. commune Han 881 or L. betulina Han 851 on Firmiana platanifolia was 1,373.12 ± 55.93 and 1,144.85 ± 34.97 U/L, respectively, higher than that from other tested conditions. L. betulina Han 851 or S. commune Han 881 mixed with other species was also helpful for accelerating laccase secretion due to reach maximum enzyme activity quickly. The treatment of mixing different species, including the mixture of two or three species, was obviously conducive to the improvement of laccase activity on Firmiana platanifolia. These results revealed that the fungal co-culture and the mixed lignocellulosic wastes contribute to the improvement of laccase activities and enhance laccase activities within a short period. These findings would be helpful for providing a new method for rapid production of low-cost laccase and for optimization of integrated industrial laccase production.

The Sustainable Production of a Novel Laccase from Wheat Bran by Bordetella sp. JWO16: Toward a Total Environment

Laccase is increasingly adopted in diverse industrial and environmental applications, due to its readily accessible requirements for efficient catalytic synthesis and biotransformation of chemicals. However, it is perceived that its industrial production might incur some unfavorable overhead, which leads to expensive market products, and the corresponding negative environmental feedback, due to the use of capital-intensive and precarious chemicals. To this end, this study was designed to evaluate the performance indicators of the valorization of wheat bran by a novel Jb1b laccase and its subsequent application in waste minimization and water management, on a laboratory scale. Optimal Jb1b laccase was produced in submerged fermentation medium containing wheat bran, an agroindustrial residue, through response surface methodology (RSM) algorithm, and was applied in dye decolorization and denim bioscouring, respectively. Results showed that the resultant enzyme manifested unique biochemical properties, such as enhanced tolerance at certain physicochemical conditions, with a residual activity of at least ca. 76%. Furthermore, phenomenally high concentrations of synthetic dyes (0.2% w v−1) were decolorized over 56 h, and a 6 h mediator-supported simultaneous denim bleaching and decolorization of wash effluent was observed. The sustainability of the production and application processes were inferred from the reusability of the fermentation sludge as a potential biofertilizer, with subsequent prospects for the biostimulation and bioaugmentation of contaminated soils, whereas the decolorized water could be adopted for other uses, amongst which horticulture and forestry are typical examples. These phenomena therefore authenticate the favorable environmental feedbacks and overhead realized in this present study.

Removal of hard COD from acidic eucalyptus kraft pulp bleach plant effluent streams using oxidoreductases

The bleach plant of a pulp and paper (P&P) mill presents a major source of wastewater containing toxic organic matter characterized as chemical oxygen demand (COD). Due to their high oxidizing power, oxidoreductases hold promise to be a key solution for the removal of dissolved organic material. Here, four oxidoreductases from different enzyme families were selected to treat bleach plant effluents. Haloperoxidase treatment of the final effluent resulted in the highest levels of decolorization (71%) and reduction of aromatic compounds (36%). Using single compound analysis, 27 low molecular weight compounds were found to be persistent throughout the wastewater treatment process and, therefore, classified as hard COD. The tested enzymes efficiently removed several of the identified COD compounds. Hence, this study suggests that the application of oxidoreductases will serve as an environmental-friendly solution for reducing waste from P&P production.

Extraction of ingredients from tea leaves using oxidative enzymatic reaction and optimization of extraction conditions

Peroxidase (POD) and polyphenol oxidase (PPO) are used as biocatalyst in many processes such as oxidization reactions, wastewater treatment, phenol synthesis and so on. The purpose of current study is enzymes extraction from biomass (tea leaves) as well as evaluation of their activation. Different parameters including temperature, buffer concentration, buffer type, buffer/tea leaves ratio, addition of high molecular weight polymers and emulsifiers, and pH were optimized in order to obtain the highest enzymes activity. Response Surface Methodology (RSM) procedure is employed for statistical analysis of enzymes extraction. It is understood from the result that PPO and POD possess the highest activity at temperatures of 25 °C and 50 °C, pH 7 and 5, buffer molarity of 0.1, and 0.05, buffer/tea leaves ratio = 5 for both, contact time = 20 min and 10 min, and presence of 6% and 3% PVP, 5% and 0% Tween 80 for PPO and POD, respectively. Amounts of highest activity for PPO and POD biocatalysts were calculated 0.42 U/mL and 0.025493 U/mL, respectively. Moreover, the entire inactivation of PPO took place after 30 min at 40 °C and 60 °C and 20 min at 80 °C. However, POD lost 35% of its activity after 30 min at 40 °C and 60 °C. The amount of 6% POD activity was kept after 45 min at 80 °C. Generally, it was indicated that POD was more resistant to thermal treatment than PPO.