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Antibiotics in ecosystems stimulate the emergence and development of antibiotic-resistant bacteria and genes, consequently posing tremendous health risks to wildlife species and humans. Laccase, a multicopper-containing oxidoreductase, is capable of nonspecifically catalyzing oxidization of multiple hazardous micropollutants, including antibiotics, with O2 as the terminal electron acceptor. Thus, laccase is recognized as a promising "green and sustainable biocatalyst" for the decontamination of antibiotics. Recently, great efforts have been made to design and exploit immobilized laccase to tackle antibiotics in the environment. In this review, the occurrence, fate, and ecological risks of antibiotics in environmental matrices are described. Moreover, the immobilized laccase-evoked removal of antibiotics, owing to immobilization technology reinforcing the stability and reusability of free laccase in bioremediation, is examined in details. In particular, advances in laccase-provoked transformation mechanisms (i.e. oxidative decomposition and radical polymerization) of antibiotics are highlighted, and a valuable guideline beneficial to large-scale practical applications is provided. Furthermore, evaluation of the intermediate products of antibiotics and their ecotoxicity in different laccase-enabled treatments is summarized. Finally, new directions for the application of laccase for effective antibiotic removal are envisaged, and several future directions to address the challenges are proposed. [ABSTRACT FROM AUTHOR]

Due to the widespread use of tetracyclines antibiotics (TCs) in livestock breeding, TCs has always caused soil pollution. TCs cannot only enter soil and water bodies through multiple channels but also accumulate in them over a long period. It is more abundant in soils, agricultural land. Primarily, should explore efficient methods for removing or degrading TCs. This review provides an overview of the birth, development and problem of soil contamination of TCs. Then focuses on the toxicity and effects of TCs on microorganisms, animals, and plants. Furthermore, in the following chapters, microbial -, plant -, animal – biodegradation methods are introduced to summarize the species and plants applied in soil TCs removal at this stage. Meanwhile, the principle mechanism of advanced oxidation processes is analyzed deeply to fill the gap. In addition, a case of microbial fuel cells based on sustainable bioenergetics with promising prospects for soil TCs removal is presented. Due to the interaction between carbonaceous materials and soil, the characteristics of adsorption method under soil environment are deeply analyzed. [ABSTRACT FROM AUTHOR]

Extracellular thermophilic multicopper oxidase i.e. laccase was purified, identified and characterized from Geobacillus stearothermophilus MB600. Fast protein liquid chromatography (FPLC) of lacasse showed a prominent peak at 610 nm. Sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) for laccase presented a molecular weight of 59.13 kDa. Analysis via Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) confirmed the presence of laccase similar to in Geobacillus thermoleovorans B23 and Geobacillus sp. LEMMY01. Laccase showed Km 0.532 mM for guaiacol and 0.307 mM for ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)). Its optimum activity was witnessed at 90°C, at pH 5.0. Laccase catalytic activity was completely inhibited by sodium dodecyl-sulfate (SDS), sodium azide (NaN3), and ethylenediaminetetraacetic acid (EDTA). Among the metal salts against Cu, Ca, Cd, and Li enhanced while Mg inhibited the enzyme activity. It was stable against Cl, I and solvents (Ethanol > Methanol > Dimethyl sulfoxide > Acetonitrile). Thermophilic laccase effectively degraded 93% of Remazol brilliant blue R, 92% Bisphenol A diglycidyle ether without mediator. [ABSTRACT FROM AUTHOR]

Ligninolytic fungi derived from coastal and marine environments, particularly mangrove swamps, are considered potential sources of novel enzymes with unique properties (thermostability, high-redox potential, salt and pH tolerance) not found in terrestrial strains, which are very attractive for the development of effective solutions for the elimination of contamination caused by the textile industry. In this study, the isolation and ligninolytic screening of 73 fungal strains derived from mangrove swamps were achieved. Ten strains showed ligninolytic potential, among which, the basidiomycete identified as INV BAS1 (Cyphellaceae family) exhibited outstanding laccase activity (11873.8 ± 329.0 UL−1). The laccase production was enhanced (5-fold) by optimizing the medium components concentration using a statistical design that combined the one factor at a time method and a central composite rotational design (CCRD), under Response Surface Methodology (RSM). Decolorization of the recalcitrant textile dye Remazol Briliant Blue R (RBBR) was carried out through fermentation and the use of enzyme extracts, reaching decolorization percentages of up to 95.64 ± 1.28 %, under alkaline and high salinity conditions. The laccase activity in the bulk extracts was the major responsible for the RBBR degradation according to gel zymography, UV-Vis and ATR-FTIR spectroscopy. These results contribute to the knowledge of fungal diversity in tropical mangroves and confirm their potential for the development of new bioremediation strategies in high-salt and alkaline effluents generated by the textile industry. [ABSTRACT FROM AUTHOR]

Purified laccases from bacterial species isolated from marine sediment were applied to degrade Bisphenol A (BPA). The Bacterial species were isolated from marine water sediments sampled from Cove Rock and Bonza Bay beach of the Eastern Cape Province, South Africa was tested for laccase activity on varied phenolic plates. The two most promising strains, Enterobacter asburiae ES1 and Enterobacter sp. Kamsi was subjected to extracellular laccase production and were identified using molecular methods. Both extracted bacterial laccases showed an affinity for ABTS and PFC substrates and were purified to homogeneity by ammonium sulfate precipitation, anion exchange, and size exclusion chromatography. A specific laccase activity of 231.67 and 218.15 U/mg of protein and a molecular weight of 50 and 55 kDa was obtained from the purified ES1 and Kamsi laccases. Laccase activity was optimum at pH8 and 5 and at 80 °C and 60 °C for ES1 and Kamsi laccases, and they manifested 71.7% and 65.8% BPA decolorizing effects. The optimized treatment condition applied showed maximum BPA removal effects of 85% and 86% at pH7 and 6, while 78% and 79% was degraded at 70 °C and 80 °C while at 250 µL enzyme volume, BPA was actively degraded to 85%, and 75% removal effect showed by ES1 and Kamsi laccases. The molecular identification of the pure colonies using 16S rRNA showed the isolate belonged to the class of gammaproteobacterial. Their nucleotide sequence has been deposited in NCBI with the accession number MN686602 and MN686603. Conclusively, marine habitat serves as a reservoir for active bacterial laccase producers suitable for bioprocess application. [ABSTRACT FROM AUTHOR]

Advanced industrialization has caused an increase in the continuous discharge of hazardous effluents in the environment. This study evaluated the potential of the laccase synthesized by Bacillus sp. NU2 to degrade five synthetic dyes. Sawdust, wheat bran and peels of banana and tangerine were utilized as carbon sources for bacterial growth and laccase production. The produced crude enzyme was purified to homogeneity to determine its molecular weight. The kinetic activity of the purified laccase was determined using 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The toxicity of the laccase-treated dye solution was assessed on Bacillus sp. NU2 growth. The result showed optimum laccase yield from the tangerine peel medium. The purified laccase gave a specific activity of 349.94 U mg−1 and a molecular weight of 55 kDa, respectively. The purified laccase displayed a strong affinity for ABTS substrate with an enzyme activity of 31.21 U mg−1. It was optimum at 60 °C and pH 8, with catalytic efficiency (Kcat/Km) of 23.93 mmol L−1. The decolourization effects on Congo Red, Methyl Orange, Remazol Brilliant Blue R, Reactive Blue 4 and Malachite Green were 87%, 70%, 65%, 63% and 51%, respectively. The toxicity assay of laccase degraded dyes on Bacillus sp. NU2 showed a growth reduction of 36.75% (Malachite Green), 12.57% (Congo Red), 17.19% (Methyl Orange), 38.41% (Remazol Brilliant Blue R) and 28.14% (Reactive Blue 4). The laccase produced by Bacillus sp. NU2 holds a high catalytic potential for the detoxification of dye effluents in an environmental system. [ABSTRACT FROM AUTHOR]

Production of an extracellular thermophilic and alkali stable laccase from Phoma herbarum isolate KU4 was reported for the first time, both in submerged fermentation (SmF, highest 1590 U/mL) and solid state fermentation (SSF, highest 2014.21 U/mL) using agro-industrial residues. The laccase was partially purified to 7.93 fold with the apparent molecular weight of 298 kDa. The enzyme had pH optimum at 5.0 and temperature optimum at 50 °C, with maximum stability at pH 8.0. It showed activity towards various phenolic and non-phenolic compounds. The kinetic parameters, Km, Vmax and Kcat of the laccase for DMP were 0.216 mM, 270.27 U/mg and 506.69 s−1, respectively. Laccase activity was inhibited by various metal ions and conventional inhibitors, however, it was slightly increased by Zn2+. The laccase showed good decolorization efficiency towards four industrial dyes, namely, methyl violet (75.66%), methyl green (65%), indigo carmine (58%) and neutral red (42%) within 24 h. FTIR analysis of the decolorized products confirmed the degradation of the dyes. The decolorization efficiency of the enzyme suggests that the partially purified laccase could be used to decolorize synthetic dyes present in industrial effluents and for waste water treatments. The thermophilic and alkali stable laccase may also have wider potential industrial applications. [ABSTRACT FROM AUTHOR]

Laccases are a group of oxidases that catalyze the oxidation of a wide range of electron rich substrates like phenolic compounds, lignin and aromatic amines. They are of interest because of their potential to be used in environmental and industrial applications. In this research, potent laccase producer fungi were screened and isolated from olive mill wastewater (OMW). One of the 23 isolated fungi was identified as Galactomyces geotrichum based on 18S rDNA sequence analysis that detected good laccase activity. Produced laccase had a molecular weight of 55 kDa that was confirmed by zymogram analysis. This is the first report about the optimization of laccase Production by G. geotrichum under solid-state fermentation. The optimization was made by the Taguchi design of experiments (DOE) methodology. An orthogonal array (L25) was designed using Minitab 19 software to study four effective process factors in five levels for laccase production. The optimum condition derived was; moisture content (80%), fermentation time (14 day), CuSO4⋅5H2O as the inducer (300 μM), glucose as a co-substrate (5 g/L). Maximum laccase activity of 52.86 (U/g of dry substrate) was obtained using optimum fermentation condition. This study aimed to better understand the laccase producing microorganisms in OMW and take them to OMW treatment that is rich in phenolic compounds. [ABSTRACT FROM AUTHOR]

The oxidation activity of multicopper-oxidases overlaps with different substrates of laccases and bilirubin oxidases, thus in the present study an integrated approach of bioinformatics using homology modeling, docking, and experimental validation was used to confirm the type of multicopper-oxidase in Myrothecium verrucaria ITCC-8447. The result of peptide sequence of M. verrucaria ITCC-8447 enabled to predict the 3 D-structure of multicopper-oxidase. It was overlapped with the structure of laccase and root mean square deviation (RMSD) was 1.53 Å for 533 and, 171 residues. The low binding energy with azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (-5.64) as compared to bilirubin (-4.39) suggested that M. verrucaria ITCC-8447 have laccase-like activity. The experimental analysis confirmed high activity with laccase specific substrates, phenol (18.3 U/L), ampyrone (172.4 U/L) and, ampyrone phenol coupling (50 U/L) as compared to bilirubin oxidase substrate bilirubin (16.6 U/L). In addition, lowest binding energy with ABTS (-5.64), syringaldazine SYZ (-4.83), guaiacol GCL (-4.42), and 2,6-dimethoxyphenol DMP (-4.41) confirmed the presence of laccase. Further, complete remediation of two hazardous model pollutants i.e., phenol and resorcinol (1.5 mM) after 12 h of incubation and low binding energy of −4.32 and, −4.85 respectively confirmed its removal by laccase. The results confirmed the presence of laccase in M. verrucaria ITCC-8447 and its effective bioremediation potential. [ABSTRACT FROM AUTHOR]

Tetracycline residues have frequently been detected in multi-environmental media, and it could induce antibiotic resistance genes (ARGs) in microorganisms, which has attracted great attention. Where biodegradation processes may be a promising strategy to remove tetracycline. Thus, this study mainly considers: (i) the degradation of tetracycline by microorganisms including single microorganisms and microbial flora; (ii) the elimination of tetracycline during biochemical treatment processes and advanced treatment systems in wastewater treatment plants (WWTPs) and constructed wetlands (CWs); (iii) the degradation of tetracycline by biological coupling processes; (iv) the confusion and problem of tetracycline biodegradation. Furthermore, the characteristics and comparison of tetracycline biodegradation have been discussed in detail. Additionally, future research directions are suggested to reduce tetracycline in the aquatic environment, especially tetracycline biodegradation and the nitrogen conversion process. Degradation of tetracycline by pure culture strains and microflora was significant. Degradation of tetracycline by biochemical treatment process was summarized. Advanced treatment process in CWs could eliminate tetracycline. Future research directions on biodegradation of tetracycline are proposed. [ABSTRACT FROM AUTHOR]

Aflatoxin B1 is a naturally occurring mycotoxin that is produced as secondary metabolite by Aspergillus spp., especially A. flavus and A. parasiticus. This is the most severe toxin due to its carcinogenic, mutagenic, and teratogenic properties. Hence, methods for toxin degradation have been received increasing interest from both scientific communities and industries. In this study, 32 isolates of Bacillus spp. from various fermented cereal products were screened for their aflatoxin B1 degradation ability. The results indicated the extracellular fraction of Bacillus subtilis BCC 42005 isolated from Iru (African locust bean) potentially possessed aflatoxin B1-degrading ability. The maximum activity of the active fraction was at 50°C and pH 8.0. The activity was stable in a wide range of pH (5.0–8.0) and temperature (25–60°C). The aflatoxin B1-degrading mechanisms of this strain may be possibly involved by enzyme(s). This extracellular fraction was not toxic at IC50 4 mg/ml and it can be combined with water as a soaking agent for maize, which results in 54% of aflatoxin B1 reduction after contact time 120 min. Hence, the extracellular fraction of Bacillus subtilis BCC 42005 can be further applied as an effective soaking agent in a pretreatment process with a practical and easy-to-implement condition and also probably used to reduce the aflatoxin B1 contamination in other foods and feeds commodities. [ABSTRACT FROM AUTHOR]

In this study, the effects of Aspergillus niger in coculture with the basidiomycetes, Trametes versicolor, T. maxima, and Ganoderma spp., were studied to assess H2O2 production and laccase (Lac), Lignin Peroxidase (LiP), and manganese peroxidase (MnP) activities. The results indicated that maximum discoloration was of 97%, in the T. maxima and A. niger coculture, where the concentration of H2O2 was 5 mg/L and 6.3 mg/L in cultures without and with dye, respectively. These concentrations of H2O2 were 1.6- and 1.8-fold higher than monocultures of T. maxima (3.37 mg/L) and A. niger (3.87 mg/L), respectively. In the same coculture, the LiP and MnP enzyme activities also increased 12-fold, (from 0.08 U/mg to 0.99 U/mg), and 67-fold, (from 0.11 U/mg to 7.4 U/mg), respectively. The Lac activity increased 1.7-fold (from 13.46 U/mg to 24 U/mg). Further, a Box–Behnken experimental design indicated a 1.8-fold increase of MnP activity (from 7.4 U/mg to 13.3 U/mg). In addition, dye discoloration regression model obtained from the Box–Behnken experimental design showed a positively correlation with H2O2, (R2 = 0.58) and a negatively correlation with Lac activity (R2 = –0.7). [ABSTRACT FROM AUTHOR]

Reverse micellar systems of nonionic surfactant Span 80/isooctane/n-hexane is used for the extraction of pectinesterase from crude aqueous extract of lemon peel waste. The effect of extraction process parameters on the extraction efficiency and activity recovery were studied in detail for the lemon peel extract. The optimum NaCl concentration (0.2 mol/L), Span 80 concentration (0.3 mol/L), the extraction phase pH (7.0), the temperature (60°C), and oscillation time (30 min) were found out and the optimized conditions for the extraction from lemon peel waste resulted in back extraction efficiencies of 52.4%. A fairly good activity recovery (83.7%) of pectinesterase is obtained under these conditions. [ABSTRACT FROM AUTHOR]

Single enzyme nanoparticles (SENs) are a state of art technology that allows immobilisation of individual enzyme molecules in a nanometre scale cross-linked polymer matrix that is covalently bonded to the enzyme. Although the method has great potential in the enzyme immobilisation, it has attracted relatively low attention from researchers over the last decade. Therefore, it can be very fruitful to apply this method to several enzymes in order to increase the understanding about the mechanisms and parameters important for the technique. In this study, Trametes versicolor laccase enzyme (TvL) was immobilised as SENs without phase transfer. The enzyme was immobilised via acryloyl chloride modification that is followed by an in situ polyacrylamide polymerisation in the water phase. The resulting single TvL nanoparticles were found to be less than 50 nm in diameter and round in shape with an activity recovery of 66.33 ± 2.57%. Both Vmax and Km values of the TvL SENs were lower than the free counterpart. However, approximately the same Kcat/Km values suggested similar catalytic efficiencies for the free and the immobilised enzymes. The significantly lower (∼2 fold) Km value of the immobilised enzyme suggested an affinity increase towards 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) upon immobilisation. Whilst the immobilised and the free enzymes showed similar thermal stabilities at 60 °C for 240 min, the immobilised form showed higher stability in solution at ambient temperature after 15 days which may suggest an increase in microbial stability. [ABSTRACT FROM AUTHOR]

Two manganese peroxidases (MnPs), MnP1 and MnP2, and a laccase, Lac1, were purified from Trametes polyzona KU-RNW027. Both MnPs showed high stability in organic solvents which triggered their activities. Metal ions activated both MnPs at certain concentrations. The two MnPs and Lac1, played important roles in dye degradation and pharmaceutical products deactivation in a redox mediator-free system. They completely degraded Remazol brilliant blue (25 mg/L) in 10–30 min and showed high degradation activities to Remazol navy blue and Remazol brilliant yellow, while Lac1 could remove 75% of Remazol red. These three purified enzymes effectively deactivated tetracycline, doxycycline, amoxicillin, and ciprofloxacin. Optimal reaction conditions were 50 °C and pH 4.5. The two MnPs were activated by organic solvents and metal ions, indicating the efficacy of using T. polyzona KU-RNW027 for bioremediation of aromatic compounds in environments polluted with organic solvents and metal ions with no need for redox mediator supplements. [ABSTRACT FROM AUTHOR]

Laccase extract (LE) from Pycnoporus sanguineus was immobilized on calcium and copper alginate–chitosan beads and applied for the removal of 17α-ethinylestradiol (EE2). Effects of immobilization conditions such as: sodium alginate (SA) concentration; LE/SA ratio and chitosan/ion (Ca+2 or Cu+2) ratio on the immobilization yield were investigated. Immobilized LE on Ca-beads and Cu-beads was then used to degrade an EE2 solution. The optimal conditions for LE immobilization on Ca-beads were: 1.5% (w/v) SA, 1:5 (v/v) LE/SA and 3:7 (v/v) chitosan/ion (Ca+2). The optimal conditions for immobilization on Cu-beads were 2.0% (w/v) SA, 0.5:5 (v/v) LE/SA and 3:7 (v/v) chitosan/ion (Cu+2). The best result was obtained for immobilized LE on Ca-beads in buffer-absent medium. Furthermore, the immobilized enzyme was reused in five cycles for EE2 removal. The formation of EE2 dimers by LE treatment has been demonstrated by electrospray ionization coupled to time of flight mass spectrometer (ESI–TOF–MS). The results evidenced that immobilized LE in alginate–chitosan–divalent cation bead is an effective alternative for EE2 removal. [ABSTRACT FROM AUTHOR]

The optimization of ligninolytic enzyme (LE) activities in a novel fungal co-culture between Pycnoporus sanguineus and Beauveria brongniartii were studied using a Plackett-Burman experimental design (PBED) and a central composite design (CCD). In addition, H2O2 role was analyzed. Laccase (EC. 1.10.3.2) and MnP (EC 1.11.1.14) activities of P. sanguineus increased 6.0- and 2.3-fold, respectively, in the co-culture with B. brongniartii. The H2O2 content was higher in the co-culture (0.33-7.12-fold) than in the P. sanguineus monoculture. The PBED revealed that yeast extract (YE), FeSO4, and inoculum amount were significant factors for laccase and MnP activities and H2O2 production in the co-culture, which increased by 8.2-, 5.2- and 1.03-fold, respectively. The YE and FeSO4 were studied using a CCD to optimize the studied response variables. Laccase activity was enhanced 1.5-fold by CCD, the optimal amount of YE was 0.366 g L−1. Quadratic term of FeSO4 modulated MnP activity and was associated with a 4.28-fold increase compared to the PBED. Both YE and its quadratic term significantly affected H2O2 production; however, the CCD did not enable an increase in H2O2 production. Pearson correlation indicated an increase in laccase (r2=0.4411, p = 0.0436) and MnP (r2=0.5186, p = 0.0198) activities following increases in H2O2 in the co-culture system. [ABSTRACT FROM AUTHOR]

By using a laccase-secretion indicator for screening laccase-producing microorganisms, a novel laccase-producing strain was isolated and identified as Paraphoma sp. strain GZS18, it produced increased laccase and mycelia at 34 °C. Further investigations showed that the production of laccase by Paraphoma sp. GZS18 was greatly enhanced by less toxic inducers copper sulphate and methyl orange. Copper sulphate and methyl orange were added into the cultivation medium at 12 and 60 h, respectively, and the maximum laccase production was obtained. Through Plackett-Burman design and response surface methodology, we obtained the optimum production conditions as follows: methyl orange, 39.90 μM; addition time of copper sulphate, 11.95 h; addition time of methyl orange, 51.40 h. Under the above conditions, the experimental value of laccase production was 12,250.76 U/L. The extracellular laccase from Paraphoma sp. GZS18 was purified to homogeneity, which showed a molecular mass of 75 kDa. N-terminal amino acid sequences was AXaVSVASREMT. [ABSTRACT FROM AUTHOR]

This research has focused on the optimization of immobilized laccase condition and utilization in degradation of acetaminophen contaminated in aqueous solution. Laccase fromLentinus polychrouswas immobilized in barium alginate. The effects of laccase immobilization such as sodium alginate concentration, barium chloride concentration and gelation time were studied. The optimal conditions for immobilization were sodium alginate 5% (w/v), barium chloride 5% (w/v) and gelation time of 60 min. Immobilized laccase was then used for acetaminophen removal. Acetaminophen was removed quickly in the first 50 min. The degradation rate and percentage of removal increased when the enzyme concentration increased. Immobilized laccase at 0.57 U/g-alginate showed the maximum removal at 94% in 240 min. The removal efficiency decreased with increasing initial acetaminophen concentration. TheKmvalue for immobilized laccase (98.86 µM) was lower than that of free laccase (203.56 µM), indicating that substrate affinity was probably enhanced by immobilization. The immobilized enzyme exhibited high activity and good acetaminophen removal at pH 7 and temperature of 35°C. The activation energies of free and immobilized laccase for degradation of acetaminophen were 8.08 and 17.70 kJ/mol, respectively. It was also found that laccase stability to pH and temperature increased after immobilization. Furthermore, immobilized laccase could be reused for five cycles. The capability of removal and enzyme activity were retained above 70%. [ABSTRACT FROM PUBLISHER]

The literature on hydrocarbon remediation with basidiomycetes was reviewed. Two ecological groups are considered for bioremediation, the saprotrophic basidiomycetes (white-rot and brown-rot fungi) and the ectomycorrhizal basidiomycetes. A remarkable capacity of basidiomycetes forin vitrodegradation of simple and recalcitrant hydrocarbons, such as PAH, persistent organic pollutants (POPs), halogenated HC, aromatic HC and phenols, explosives and dyes was reported for many species. However, there is a need for more studies on the practical feasibility of field applications with basidiomycetes. [ABSTRACT FROM AUTHOR]

Dye decolourizing potential of laccase obtained from the white rot fungusTrametestrogiiwas studied for two reactive dyes; namely Reactive Black 5 (diazoic) and Reactive Violet 5 (monoazoic). The presence of a redox mediator as 1-hydroxybenzotriazole (HBT) was found to be essential for the decolourization of the said two dyes. The optimization of the decolourization process using experimental design was studied with three variables: dye (25, 50, 100 mg/L), enzyme (0.1; 0.5; 1 U/mL) and redox mediator (0.1; 0.5; 1 mM) concentrations. Results of this investigation revealed that the optimum concentrations of dye, enzyme and HBT for the degradation of the Reactive Black 5 (RB5) were 25 mg/L, 1U/mL and 1 mM, respectively, for a maximum decolourization about 93%. However, the optimum concentrations for Reactive Violet 5 (RV5) were found to be 25 mg/L, 0.5 U/mL and 0.5 mM, for a total removal of the dye. The apparent capacity of this laccase to decolourize azo dyes make it a suitable candidate for further applications in biobleaching and the treatment of textile effluents. [ABSTRACT FROM PUBLISHER]

This investigation was undertaken to determine the atrazine degradation by fungal enzyme extracts (FEEs) in a clay-loam soil microcosm contaminated at field application rate (5 μg g−1) and to study the influence of different soil microcosm conditions, including the effect of soil sterilization, water holding capacity, soil pH and type of FEEs used in atrazine degradation through a 24factorial experimental design. TheTrametes maxima–Paecilomyces carneusco-culture extract contained more laccase activity and hydrogen peroxide (H2O2) content (laccase = 18956.0 U mg protein−1, H2O2= 6.2 mg L−1) than theT. maximamonoculture extract (laccase = 12866.7 U mg protein−1, H2O2= 4.0 mg L−1). Both extracts were able to degrade atrazine at 100%; however, theT. maximamonoculture extract (0.32 h) achieved a lower half-degradation time than its co-culture withP. carneus(1.2 h). The FEE type (p= 0.03) and soil pH (p= 0.01) significantly affected atrazine degradation. The best degradation rate was achieved by theT. maximamonoculture extract in an acid soil (pH = 4.86). This study demonstrated that both the monoculture extracts of the native strainT. maximaand its co-culture withP. carneuscan efficiently and quickly degrade atrazine in clay-loam soils. [ABSTRACT FROM AUTHOR]

The goal of this study was to determine the optimum conditions for the enzymatic decolorization of eleven dyes by laccase. The dyes Cibacron Orange P-4 R, Direct Black VSF 600, Cibacron Red P-4B, Remazol Red, Burdirect Brown M, Burdirect Black Metakonz, Burdirect Dark Blue BH, Burdirect Blue 6B, Cibacron Black PSG, Burdirect Green B, and Remazol Turquoise Blau G133 were characterized spectrophotometrically. The dye that had the highest degree of decolorization (97%), Cibacron Orange P-4 R, was selected for further study. Optimum conditions for decolorization were a 1 mM initial dye concentration at pH 7.0 and an initial enzyme activity of 0.084 U at 25°C for 135 min. Sodium sulfate was selected as the activator at 50 mM. The decolorized products were characterized by infrared spectroscopy and gas chromatography–mass spectrometry. No degradation products were identified following removal of 97% of the dye. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass (LB) is a promising sugar feedstock for biofuels and other high-value chemical commodities. The recalcitrance of LB, however, impedes carbohydrate accessibility and its conversion into commercially significant products. Two important factors for the overall economization of biofuel production is LB pretreatment to liberate fermentable sugars followed by conversion into ethanol. Sustainable biofuel production must overcome issues such as minimizing water and energy usage, reducing chemical usage and process intensification. Amongst available pretreatment methods, microorganism-mediated pretreatments are the safest, green, and sustainable. Native biodelignifying agents such as Phanerochaete chrysosporium, Pycnoporous cinnabarinus, Ceriporiopsis subvermispora and Cyathus stercoreus can remove lignin, making the remaining substrates amenable for saccharification. The development of a robust, integrated bioprocessing (IBP) approach for economic ethanol production would incorporate all essential steps including pretreatment, cellulase production, enzyme hydrolysis and fermentation of the released sugars into ethanol. IBP represents an inexpensive, environmentally friendly, low energy and low capital approach for second-generation ethanol production. This paper reviews the advancements in microbial-assisted pretreatment for the delignification of lignocellulosic substrates, system metabolic engineering for biorefineries and highlights the possibilities of process integration for sustainable and economic ethanol production. [ABSTRACT FROM AUTHOR]

Studies on laccase production byDaedalea flavidawere carried out in static and low-speed shake cultures. The enzyme production was reduced drastically at a high speed of shaking. Optimal production conditions are necessary to assess the quality of laccase suitable for a specific application. Thus, the production of laccase was optimized by the application of response surface methodology. Laccase production was 8-fold and 7.5-fold more in static and low-speed shake conditions, respectively, in an optimal medium composition than in an unoptimized medium. Laccase obtained using the optimal culture medium ofD. flavidawas tested for its stability at different temperatures and pH conditions. The partially purified enzyme was most stable at 30°C and pH 5. The half-life of laccase is 87 min at 60°C and at pH 6. The kinetic and thermodynamic parameters were evaluated for the inactivation of the partially purified laccase. The entropy change of inactivation of the enzyme is least at pH 4. [ABSTRACT FROM PUBLISHER]

White-rot fungal species belonging to Ganoderma have long been used as medicinal mushrooms in many Asian countries. In recent years, however, attention is not just being paid to their pharmacological properties, but to their other potentially valuable features as well, including their secretion of enzymes which decompose lignin. The current literature regarding lignin-modifying enzymes from the genus Ganoderma, their potential uses, and the components, structures and processes of lignocellulose degradation are discussed. The ligninolytic enzymes from the genus Ganoderma, as well as the number of additional enzymes that participate in lignin degradation, are summarized; further, the potential applications of these enzymes are analyzed and probed in this article. This review will provide insight on the valuable applications of Ganoderma spp. and will serve as a useful reference on the use of lignocellulose degradation as a means of environmental protection. [ABSTRACT FROM AUTHOR]

Phenolic compounds that are produced by variety of industrial and urban activities pose dangers to live organisms and the environment. Here, an inducible phenol-degrading system was designed and constructed inEscherichia colias the host. CapR as a transcription activator in Pseudomonas species shows sensitivity towards most common phenolic pollutants. Upon presence of inducible pollutants and conformational changes of CapR, an inducible promoter will trigger the expression of a bacterial laccase gene, which had been isolated previously from a local Bacillus species. Laccase as a multicopper oxidase has the ability to oxidize wide variety of mono and polyphenols. The sensitivity of the inducible system was verified in the presence of phenol with the concentration range of 1 nM–10 mM. A linear correlation was observed between laccase expression and phenol concentration up to 1 mM. Laccase was expressed even in the lowest concentration of phenol (1 nM) after 2 hr of exposure. 2,2-Azinobis (3-ethylbenzthiazoline-6-sulfonate) (ABTS) as a mediator of laccase oxidative reactions could induce laccase expression through conformational changes of CapR. Recognition of ABTS by CapR not only results in expression of the remediating enzyme but also extends its substrate range to nonphenolic compounds. [ABSTRACT FROM PUBLISHER]

Laccase was produced fromPleurotus floridaunder solid-state fermentation, and the production was optimized by response surface methodology. The predicted maximum laccase production of 8.81 U g−1was obtained by the optimum concentration of malt extract, banana peel, wheat bran and CuSO4, which was found to be 0.69 g, 10.61 g, 10.68 g and 77.15 ppm, respectively. The validation results suggested that the laccase production was 7.96 U g−1in the optimized medium, which was close to the predicted value. Decolorization efficiency ofP. floridalaccase was evaluated against malachite green (MG). Rapid decolorization of MG dye was observed, and a dark-coloured precipitate was formed in the reaction mixture. HPLC analysis indicated that the laccase enzyme degraded MG by the demethylation process. The toxicity of MG was reduced to 67% after the treatment with laccase, which was confirmed by a phytotoxicity study. [ABSTRACT FROM PUBLISHER]

During directed evolution to functionally express the high redox potential laccase from the PM1 basidiomycete in Saccharomyces cerevisiae, the characteristic maximum absorption at the T1 copper site (Abs610T1Cu) was quenched, switching the typical blue colour of the enzyme to yellow. To determine the molecular basis of this colour change, we characterized the original wild-type laccase and its evolved mutant. Peptide printing and MALDI-TOF analysis confirmed the absence of contaminating protein traces that could mask the Abs610T1Cu, while conservation of the redox potential at the T1 site was demonstrated by spectroelectrochemical redox titrations. Both wild-type and evolved laccases were capable of oxidizing a broad range of substrates (ABTS, guaiacol, DMP, synapic acid) and they displayed similar catalytic efficiencies. The laccase mutant could only oxidize high redox potential dyes (Poly R-478, Reactive Black 5, Azure B) in the presence of exogenous mediators, indicating that the yellow enzyme behaves like a blue laccase. The main consequence of over-expressing the mutant laccase was the generation of a six-residue N-terminal acidic extension, which was associated with the failure of the STE13 protease in the Golgi compartment giving rise to alternative processing. Removal of the N-terminal tail had a negative effect on laccase stability, secretion and its kinetics, although the truncated mutant remained yellow. The results of CD spectra analysis suggested that polyproline helixes were formed during the directed evolution altering spectral properties. Moreover, introducing the A461T and S426N mutations in the T1 environment during the first cycles of laboratory evolution appeared to mediate the alterations to Abs610T1Cu by affecting its coordinating sphere. This laccase mutant is a valuable departure point for further protein engineering towards different fates. [ABSTRACT FROM AUTHOR]

This study deals with the characterization of laccase enzyme activity produced by Cryptococcus albidus. Industrial wastes like effluent and sludge are complex mixtures of a number of chemicals. These chemicals can interfere with the proper functioning of the enzymes used for bioremediation. Thus, it is important to study the effect of such interfering solvents, detergents, metal chelators, and other chemicals on enzyme activity before industrial applications. Laccase showed maximum activity at pH 2.5 and temperature 20–30°C when ABTS was used as a substrate. The enzyme followed Michaelis–Menten kinetics: Km was 0.8158 mM and Vmax was 1527.74 U/mg. Laccase showed good thermostability with a half-life of 81 min at 25°C, 77 min at 35°C, 64 min at 45°C, 36 min at 55°C, and 21 min at 65°C. There was no effect of sodium dodceyl sulfate (SDS) (0.1–1.0%) and EDTA (0.1–0.5%) on laccase activity. Sodium azide and 2-mercaptoethanol showed complete inhibition of laccase activity at 0.1% concentration. At lower concentrations of acetone and acetonitrile, laccase was able to maintain its activity. However, the activity was completely inhibited at a concentration of 50% or above of acetone, methanol, 1,4-dioxan, and acetonitrile. [ABSTRACT FROM PUBLISHER]

Azo dyes represent the largest class of industrial colorants. These are no longer used only for the coloration of textiles, plastics, paints, inks, and lacquers, but rather serve as key components in high-tech applications such as optical data storage, reprographics, display devices, dye-sensitized solar cells, energy transfer cascades, light-emitting diodes, laser welding processes, or heat management systems. Azo dyes are also of growing importance in the medical and biomedical fields. In most of these applications, the color is largely irrelevant and it is the ability of the colorants to absorb visible electromagnetic radiation with high efficiency, or other functional property, that is exploited. With the growing awareness and environmental concerns, it is imperative that the hierarchy of reduce, reuse, and degrade be adopted and measures be taken to remove color from the industrial discharge. The present review (a) embodies a comparison of the present decolorization/degradation techniques for water-soluble and insoluble dyes, (b) describes their advantages and limitations, (c) discusses various mechanisms, and (d) focuses on the present literature on microbial decolorization of textile dyes specifically by using bacteria, fungus, yeast, and algae. Also, for the first time an attempt has been made to comprehensively compile chemical and biological decolorization/degradation of disperse dyes. The research on the decolorization of textile dyes has mainly been focused on water-soluble dyes, while decolorization of disperse dyes that are water insoluble have received only scant attention and constitutes a topical area of concern as these dyes persist for a longer duration in textile effluents. Given the limitations (vide infra) of the chemical treatment methods, decolorization using biological means is an interesting option. [ABSTRACT FROM AUTHOR]

Laccases are multicopper proteins that use molecular oxygen to oxidize a broad spectrum of organic compounds by a radical-catalyzed reaction mechanism. Many articles over the past 15 years have touted the diverse potential applications of laccase in various biotechnological processes. This review covers the natural roles of the enzyme, its structural properties, substrates, reaction mechanism, and inhibitors, as well as its applications regarding the detoxification and bioremediation of polluted wastewaters and soils. Other applications are briefly covered as well. The authors critically assess the advantages, shortcomings, and future needs relating to laccase availability, effectiveness, and cost-efficiency, and also provide numerous references to the many divisions of research into this multifaceted enzyme. [ABSTRACT FROM AUTHOR]

An enzymatic approach has attracted much interest in the remediation/degradation of various organic pollutants present in the wastewater coming out of industries. The treatment of several pollutants sometimes causes problems due to the recalcitrant nature of the compounds. However, these recalcitrant compounds were degraded/transformed by enzymes in the presence of certain redox mediators. These redox mediators enhanced the range of substrates and efficiency of degradation of the recalcitrant compounds by severalfold. Enzymes whose potential has been exploited for this purpose are laccases, lignin peroxidases, manganese peroxidases, horseradish peroxidases, turnip peroxidases, bitter gourd peroxidases, and others. Several redox mediators have been reported in the literature but very few of them are frequently used, for example, 1-hydroxybenzotriazole, veratryl alcohol, violuric acid, 2-methoxy-phenothiazone, 3-hydroxyanthranilic acid, anthraquinone 2,6-disulfonic acid, 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), N-hydroxyacetanilide, phenol red, 3,3',5,5'-tetramethyl benzidine; dichlorophenol red, 2,2',6,6'-tetramethylpiperidine-N-oxyl radical, syringaldehyde and acetosyringone, and others. In the near future the enzyme-redox mediator combined treatment of aromatic compounds present in the industrial effluents/wastewater will play a vital role. Use of the enzyme-redox mediator system certainly will enhance the chances of remediation of a wide spectrum of aromatic compounds present in various industrial effluents. [ABSTRACT FROM AUTHOR]

Fungal laccases are useful for several remarkable transformations, such as bioremediation of polycyclic aromatic hydrocarbons (PAHs), synthesis of phenolic-based resins, oxidation of lignin derivatives and others. Most of these substrates are barely water-soluble, and although polar organic co-solvents may be added to enhance their solubility, transformation rates dramatically decrease due to the negative effect of organic solvents on the protein structure. Laccase from Myceliophthora thermophila variant T2 (MtLT2) has been submitted to laboratory evolution in Saccharomyces cerevisiae with the aim of improving activity and stability in organic co-solvents. Some 4500 clones created by random mutagenesis were screened in two rounds of directed evolution. Libraries were explored under increasing concentrations of acetonitrile and ethanol, and several mutants with improved features were purified and further characterised. Turnover rates of MtLT2 in 30% (v/v) acetonitrile and 50% (v/v) ethanol were increased up to 6.5- and 7.5-fold, respectively. The best variants showed similar rates in 20% (v/v) acetonitrile or 30% (v/v) ethanol as the parent type in aqueous media. Mutant laccases were also tested for the oxidation of anthracene in the presence of 20% (v/v) acetonitrile. [ABSTRACT FROM AUTHOR]

A biosensor was developed by immobilizing laccase onto mercury thin film electrode (MTFE) by means of gelatin that is then crosslinked with glutaraldehyde. Mercury thin film (MTF) was deposited onto glassy carbon electrode (GCE) and the obtained biosensor was utilized for the determination of phenolic compounds. The measurement was based on the amperometric detection of oxygen consumption in relation to analyte oxidation. The optimum experimental conditions for the biosensor were investigated and the system was calibrated for both catechol and phenol. A linear relationship between sensor responses and analyte concentrations was obtained in concentration range between 0.5 × 10 -6 – 5.0 × 10 -6 M for catechol and 2.5 × 10 -6 – 2.0 × 10 -6 M for phenol, respectively. Mercury thin film was also formed onto the surface of screen printed graphite electrodes and applied for the catechol detection. The linearity was observed in concentration range between 2.5 × 10 -6 – 3.0 × 10 -5 M. [ABSTRACT FROM AUTHOR]