Decolorization of Remazol Brilliant Blue R by a purified laccase of Polyporus brumalis

Laccase-mediated formation of hydrogels based on silk-elastin-like protein polymers with ultra-high molecular weight

As artificial extracellular matrix-like materials, silk-elastin-like protein (SELP) hydrogels, with excellent mechanical properties, high tunability, favorable biocompatibility, and controlled degradability, have become an important candidate in biomedical materials. In this study, SELP is composed of silk-like (GAGAGS) and elastin-like (GXGVP) tandem repeats, in which X residues are set as tyrosine and lysine. Furthermore, SELP polymers are prepared via SpyTag/SpyCatcher. To explore a gentler and more efficient enzymatic crosslinking method, an innovative method was invented to apply laccase to catalyze the formation of SELP hydrogels. Gelation could be successfully achieved in 2-5 min . SELP hydrogels mediated by laccase had the characteristic of low swelling rate, which could maintain a relatively stable shape even when immersed in water, and hence had the potential to be further developed into injectable biomaterials. Additionally, SELP hydrogels cross-linked by laccase showed excellent biocompatibility verified by L929 and HEK 293 T cells with cell viability >93.8 %. SELP hydrogels also exhibit good properties in sustained drug release and cell encapsulation in vitro. This study demonstrates a novel method to construct SELP hydrogels with excellent biocompatibility and expands the possibility of SELP-based material applications in biomedical fields.

Fabrication of TiO2@ITO-grown nanocatalyst as efficient applicant for catalytic reduction of Eosin Y from aqueous media

Innovative titania nanostructures were synthesized via efficient and prolific liquid phase deposition route and efficiently utilized for catalytic degradation of Eosin Y. The as-synthesized TiO₂@ITO nanostructures were subjected to various characterization tactics that confirmed the efficacious fabrication of nanostructures. The minute size of particles around 5-6 nm having anatase crystalline phase and concrete like morphology was greatly revealed by atomic force microscopy, XRD, and SEM, respectively. The resulting nanoconcretes were employed for photocatalytic degradation of Eosin Y dye in aqueous medium. The effects of various experimental parameters such as the reducing agent concentration, sunlight, time, catalytic dose, and microwave power were investigated for the potential photocatalytic degradation. The proposed TiO₂@ITO nanostructures showed potential photocatalytic efficiency then previously reported nanomaterial for degradation of toxic Eosin Y dye; it shows approximately 99.8% dye degraded within 50-60 s using only 100 μg of nanocatalyst under optimized conditions. Owing to minute size, topography and electron-hole pair abilities TiO₂@ITO nanostructures suggest an exceptional icon at the commercial level for successful degradation of toxic pollutants.Graphical abstract.

Optimization and kinetic modeling of Trametes maxima IIPLC-32 laccase and application in recalcitrant dye decolorization

Enhanced laccase production by the Trametes maxima fungus and its use for decolorization of the textile dye RBBR.

Characterization and Dye Decolorization Potential of Two Laccases from the Marine-Derived Fungus Pestalotiopsis sp

Two laccase-encoding genes from the marine-derived fungus Pestalotiopsis sp. have been cloned in Aspergillus niger for heterologous production, and the recombinant enzymes have been characterized to study their physicochemical properties, their ability to decolorize textile dyes for potential biotechnological applications, and their activity in the presence of sea salt. The optimal pH and temperature of PsLac1 and PsLac2 differed in relation to the substrates tested, and both enzymes were shown to be extremely stable at temperatures up to 50 °C, retaining 100% activity after 3 h at 50 °C. Both enzymes were stable between pH 4–6. Different substrate specificities were exhibited, and the lowest K_m and highest catalytic efficiency values were obtained against syringaldazine and 2,6-dimethoxyphenol (DMP) for PsLac1 and PsLac2, respectively. The industrially important dyes—Acid Yellow, Bromo Cresol Purple, Nitrosulfonazo III, and Reactive Black 5—were more efficiently decolorized by PsLac1 in the presence of the redox mediator 1-hydroxybenzotriazole (HBT). Activities were compared in saline conditions, and PsLac2 seemed more adapted to the presence of sea salt than PsLac1. The overall surface charges of the predicted PsLac three-dimensional models showed large negatively charged surfaces for PsLac2, as found in proteins for marine organisms, and more balanced solvent exposed charges for PsLac1, as seen in proteins from terrestrial organisms.

Expression, purification, and characterization of a novel laccase from Setosphaeria turcica in Eschericha coli

Laccases are multicopper oxidases (E.C. 1.10.3.2) that catalyze the oxidation of many phenolic compounds. In this study, a novel laccase, Stlac4, from Setosphaeria turcica was cloned and expressed in Escherichia coli by insertion into the pET-30a expression plasmid. The recombinant laccase was purified and visualized on SDS-PAGE as a single band with an apparent molecular weight of 71.5 KDa, and confirmed by Western blot. The maximum activity of the purified laccase was 127.78 U · mg^-1 , the optimum temperature and pH value were 60 °C and 4.0 respectively, measured by oxidation of 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS). Purified laccase activity under different metal ions and an inhibitor were tested, revealing that laccase activity increased by approximately 434.8% with Fe³⁺ , and 217.4% with Cu²⁺ at 10 mmol · L^-1 concentrations, Mn²⁺ increased the laccase activity only at 5 mmol · L^-1 , while Na⁺ increased activity at 1 mmol · L^-1 but inhibited activity at 5 and 10 mmol · L^-1 . SDS increased laccase activity at 1 mmol · L^-1 , and inhibited activity at 5 and 10 mmol · L^-1 .

Heterologous expression and characterisation of a laccase from Colletotrichum lagenarium and decolourisation of different synthetic dyes

Laccases have received considerable attention in recent decades because of their ability to oxidise a large spectrum of phenolic and non-phenolic organic substrates and highly recalcitrant environmental pollutants. In this research, a laccase gene from Colletotrichum lagenarium was chemically synthesised using yeast bias codons and expressed in Pichia pastoris. The molecular mass of the recombinant laccase was estimated to be 64.6 kDa by SDS-PAGE, and the enzyme exhibited maximum activity at pH 3.6-4.0 but more stability in buffer with higher pH (>pH 3.6). The optimal reaction temperature of the enzyme was 40 °C, beyond which stability significantly decreased. By using 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulphonate (ABTS) as a substrate, K m and V max values of 0.34 mM and 7.11 mM min(-1) mg(-1), respectively, were obtained. Using ABTS as a mediator, the laccase could oxidise hydroquinone to p-benzoquinone and decolourise the synthetic dyes malachite green, crystal violet and orange G. These results indicated that the laccase could be used to treat industrial effluents containing artificial dyes.

Photodegradation of Eosin Y Using Silver-Doped Magnetic Nanoparticles

The purification of industrial wastewater from dyes is becoming increasingly important since they are toxic or carcinogenic to human beings. Nanomaterials have been receiving significant attention due to their unique physical and chemical properties compared with their larger-size counterparts. The aim of the present investigation was to fabricate magnetic nanoparticles (MNPs) using a coprecipitation method, followed by coating with silver (Ag) in order to enhance the photocatalytic activity of the MNPs by loading metal onto them. The fabricated magnetic nanoparticles coated with Ag were characterised using different instruments such as a scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDAX) spectroscopy, and X-ray diffraction (XRD) analysis. The average size of the magnetic nanoparticles had a mean diameter of about 48 nm, and the average particle size changed to 55 nm after doping. The fabricated Ag-doped magnetic nanoparticles were used for the degradation of eosin Y under UV-lamp irradiation. The experimental results revealed that the use of fabricated magnetic nanoparticles coated with Ag can be considered as reliable methods for the removal of eosin Y since the slope of evaluation of pseudo-first-order rate constant from the slope of the plot between ln⁡(C_o/C) and the irradiation time was found to be linear. Ag-Fe₃O₄ nanoparticles would be considered an efficient photocatalyst to degrade textile dyes avoiding the tedious filtration step.

Overexpression of a novel thermostable and chloride-tolerant laccase from Thermus thermophilus SG0.5JP17-16 in Pichia pastoris and its application in synthetic dye decolorization

Laccases have been used for the decolorization and detoxification of synthetic dyes due to their ability to oxidize a wide variety of dyes with water as the sole byproduct. A putative laccase gene (LacTT) from Thermus thermophilus SG0.5JP17-16 was screened using the genome mining approach, and it was highly expressed in Pichia pastoris, yielding a high laccase activity of 6130 U/L in a 10-L fermentor. The LacTT open reading frame encoded a protein of 466 amino acid residues with four putative Cu-binding regions. The optimal pH of the recombinant LacTT was 4.5, 6.0, 7.5 and 8.0 with 2,2'-azino-bis(3-ethylbenzothazoline-6-sulfonic acid) (ABTS), syringaldazine (SGZ), guaiacol, and 2,6-dimethoxyphenol (2,6-DMP) as the substrate, respectively. The optimal temperature of LacTT was 90°C with guaiacol as the substrate. LacTT was highly stable at pH 4.0-11.0 and thermostable at 40°C-90°C, confirming that it is a pH-stable and thermostable laccase. Furthermore, LacTT also exhibited high tolerance to halides such as NaCl, NaBr and NaF, and decolorized 100%, 94%, 94% and 73% of Congo Red, Reactive Black B and Reactive Black WNN, and Remazol Brilliant Blue R, respectively. Interestingly, addition of high concentration of NaCl increased the RBBR decolorization efficiency of LacTT. These results suggest that LacTT is a good candidate for industrial applications such as dyestuff processing and degradation of dyes in textile wastewaters.

Enhanced bio-decolorization of 1-amino-4-bromoanthraquinone-2-sulfonic acid by Sphingomonas xenophaga with nutrient amendment

Bacterial decolorization of anthraquinone dye intermediates is a slow process under aerobic conditions. To speed up the process, in the present study, effects of various nutrients on 1-amino-4-bromoanthraquinone-2-sulfonic acid (ABAS) decolorization by Sphingomonas xenophaga QYY were investigated. The results showed that peptone, yeast extract and casamino acid amendments promoted ABAS bio-decolorization. In particular, the addition of peptone and casamino acids could improve the decolorization activity of strain QYY. Further experiments showed that l-proline had a more significant accelerating effect on ABAS decolorization compared with other amino acids. l-Proline not only supported cell growth, but also significantly increased the decolorization activity of strain QYY. Membrane proteins of strain QYY exhibited ABAS decolorization activities in the presence of l-proline or reduced nicotinamide adenine dinucleotide, while this behavior was not observed in the presence of other amino acids. Moreover, the positive correlation between l-proline concentration and the decolorization activity of membrane proteins was observed, indicating that l-proline plays an important role in ABAS decolorization. The above findings provide us not only a novel insight into bacterial ABAS decolorization, but also an l-proline-supplemented bioaugmentation strategy for enhancing ABAS bio-decolorization.

Purification and biochemical characterization of a new alkali-stable laccase from Trametes sp. isolated in Tunisia: role of the enzyme in olive mill waste water treatment

A white-rot basidiomycete, isolated from decayed acacia wood (from Northwest of Tunisia) and identified as Trametes sp, was selected in a broad plate screening because of its ability to decolorize and dephenolize olive oil mill wastewater (OMW) efficiently. The major laccase was purified and characterized as a monomeric protein with apparent molecular mass of 61 kDa (SDS-PAGE). It exhibits high enzyme activity over broad pH and temperature ranges with optimum activity at pH 4.0 and a temperature of 60 °C. The purified laccase is stable at alkaline pH values. The enzyme retained 50 % of its activity after 90 min of incubation at 55 °C. Using ABTS, this laccase presented K m and V max values of 0.05 mM and 212.73 μmoL min(-1) mg(-1), respectively. It has shown a degrading activity towards a variety of phenolic compounds. The purified laccase was partially inhibited by Fe(2+), Zn(2+), Cd(2+) and Mn(2+), while Cu(2+) acted as inducer. EDTA (10 mM) and NaN3 (10 mM) were found to completely inhibit its activity. 73 % OMW was dephenolized after 315 min incubation at 30 °C with 2 U mL(-1) of laccase and 2 mM HBT.

Purification, biochemical characterization and dye decolorization capacity of an alkali-resistant and metal-tolerant laccase from Trametes pubescens

Extracellular laccase (Tplac) from Trametes pubescens was purified to homogeneity by a three-step method, which resulted in a high specific activity of 18.543 Umg(-1), 16.016-fold greater than that of crude enzyme at the same level. Tplac is a monomeric protein that has a molecular mass of 68 kDa. The enzyme demonstrated high activity toward 1.0mM ABTS at an optimum pH of 5.0 and temperature of 50 °C, and under these conditions, the catalytic efficiency (k(cat)/K(m)) is 8.34 s(-1) μM(-1). Tplac is highly stable and resistant under alkaline conditions, with pH values ranging from 7.0 to 10.0. Interestingly, above 88% of initial enzyme activity was maintained in the presence of metal ions at 25.0mM, leading to an increase in substrate affinity, which indicated that the laccase is highly metal-tolerant. These unusual properties demonstrated that the new fungal laccase Tplac has potentials for the specific industrial or environmental applications.

The novel role of fungal intracellular laccase: used to screen hybrids between Hypsizigus marmoreus and Clitocybe maxima by protoplasmic fusion

Laccase has been proved important in decolorization of Remazol Brilliant Blue R (RBBR), oxidation of 2, 2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, lignin degradation and fruiting-body formation. The decolorization of RBBR by laccase was firstly used to screen protoplast fusants. Fusants were obtained by protoplast fusion between the strains of Hypsizigus marmoreus and Clitocybe maxima, and two fusants (IM1 and IIIM5) were screened on PDA medium containing RBBR. These fusants were significant higher in laccase activity than H. marmoreus, nearly 413 and 395 times, respectively. Their hyphal growth rates were also remarkable higher than H. marmoreus, nearly 1.5 and 1.4 times, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed these fusants contained the laccase, and the molecular mass of the laccase was consistent with the laccase of C. maxima, nearly 62 kDa. The pileus color of the IM1 and IIIM5 also showed partial recombined characteristics comparing to the parental strains, while biological efficiency ratios were prominent higher than that of H. marmoreus, up to 14.58 and 10.87 %, respectively. Randomly amplified polymorphic DNA bands of fusants not only were similar to parental bands, but presented new non-parental bands. Using the Unweighted pair-group method together with mathematic averages method to gain a dendrogram, in which the fusants showed intra-cluster variations. Significantly, H. marmoreus was the dominant parent, while C. maxima were distant from the fusants. The differences among IM1, IIIM5 and H. marmoreus, and the similarities among IM1, IIIM5 and C. maxima indicated IM1 and IIIM5 were somatic hybrids of H. marmoreus and C. maxima. Accordingly, it is feasible to use laccase to screen fusants of H. marmoreus and C. maxima.