An alkaline bacterial laccase for polymerization of natural precursors for hair dye synthesis.
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ABSTRACT:
SUBMITTER: Kumar D
PROVIDER: S-EPMC5851942 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Conductive and colored bacterial cellulose (BC) was developed by entrapment of polyaniline (PANi) onto dry BC membranes. The polyaniline was produced by in situ green polymerization of aniline by Myceliophthora thermophila laccase at pH = 4, 25°C, in the presence of a mediator, 1-hydroxybenzotriazol (HBT), using two different reactors, a water bath (WB) and an ultrasonic bath (US). MALDI-TOF and 1H NMR characterization of the experiment solutions confirmed the efficient polymerization of aniline by laccase. The dried BC membranes with entrapped polyaniline showed electrical conductive behavior and strong coloration, opening novel routes for the exploitation of functionalized bacterial cellulose as a green material for technical textiles, wearables, and other applications.
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Project description:Laccase efficiently catalyses polymerization of phenolic compounds. However, knowledge on applications of polymers synthesized in this manner remains scarce. Here, the potential of laccase-catalysed polymerization of natural phenols to form products useful in hair dyeing was investigated. All 15 tested phenols yielded coloured products after laccase treatment and colour diversity was attained by using mixtures of two phenolic monomers. After exploring colour differentiation pattern of 120 different reactions with statistical regression analysis, three monomer combinations, namely gallic acid and syringic acid, catechin and catechol, and ferulic acid and syringic acid, giving rise to brown, black, and red materials, respectively, were further characterized because such colours are commercially important for grey hair dyeing. Selected polymers could strongly absorb visible light and their hydrodynamic sizes ranged from 100 to 400 nm. Analyses of enzyme kinetic constants, liquid chromatography and electrospray ionization-mass spectrometry (ESI-MS) coupled with collision-induced dissociation MS/MS indicate that both monomers in reactions involving catechin and catechol, and ferulic acid and syringic acid, are coloured by heteropolymer synthesis, but the gallic acid/syringic acid combination is based on homopolymer mixture formation. Comparison of colour parameters from these three reactions with those of corresponding artificial homopolymer mixtures also supported the idea that laccase may catalyse either hetero- or homo-polymer synthesis. We finally used selected materials to dye grey hair. Each material coloured hair appropriately and the dyeing showed excellent resistance to conventional shampooing. Our study indicates that laccase-catalysed polymerization of natural phenols is applicable to the development of new cosmetic pigments.
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Project description:Laccases are a class of multicopper oxidases that catalyse the one-electron oxidation of four equivalents of a reducing substrate, with the concomitant four-electron reduction of dioxygen to water. Typically, they catalyse many anabolic reactions, in which mostly phenolic metabolites were subjected to oxidative coupling. Alternatively, laccases catalyse the degradation or modification of biopolymers like lignin in catabolic processes. In recent years, laccases have proved valuable and green biocatalysts for synthesising compounds with therapeutic value, including antitumor, antibiotic, antimicrobial, and antioxidant agents. Further up to date applications include oxidative depolymerisation of lignin to gain new biomaterials and bioremediation processes of industrial waste. This review summarizes selected examples from the last decade's literature about the laccase-mediated synthesis of biologically active natural products and their analogues; these will include lignans and neolignans, dimeric stilbenoids, biflavonoids, biaryls and other compounds of potential interest for the pharmaceutical industry. In addition, a short section about applications of laccases in natural polymer modification has been included.
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Project description:Engineering of fungal laccases with optimum catalytic activity at alkaline pH has been a long-lasting challenge. In this study, a mutant library containing 3000 clones was obtained by error-prone PCR to adapt the optimum pH of a fungal laccase Lcc9 from the basidiomycete Coprinopsis cinerea. After three rounds of functional screening, a mutant with three amino acid changes (E116K, N229D, I393T) named PIE5 was selected. PIE5 showed an optimum pH of 8.5 and 8.0 against guaiacol and 2,6-DMP when expressed in Pichia pastoris, representing the first fungal laccase that possesses an optimum pH at an alkaline condition. Site directed mutagenesis disclosed that N229D contributed the most to the optimum pH increment. A single N229D mutation caused an increase in optimum pH by 1.5 units. When used in indigo dye decolorization, PIE5 efficiently decolorized 87.1 ± 1.1% and 90.9 ± 0.3% indigo dye at the optimum conditions of pH 7.0-7.5 and 60 °C, and with either methyl 3,5-dimethoxy-4-hydroxybenzoate or 2,2'-azino-bis(3-ethylbenzothazoline-6-sulfonate) as the mediator. In comparison, the commercially available fungal laccase TvLac from Trametes villosa decolorized 84.3 ± 1.8% of indigo dye under its optimum conditions (opt. pH 5.0 and 60 °C). The properties of an alkaline-dependent activity and the high indigo dye decolorization ability (1.3-fold better than the parental Lcc9) make the new fungal laccase PIE5 an alternative for specific industrial applications.
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Project description:Laccase-mediated systems are a green route to accelerate the oxidation of aniline and obtain polyaniline with conductive properties. The synthesis of green polyaniline (emeraldine salt) was herein improved by the inclusion of additives like sodium bis (2-ethyl hexyl) sulfosuccinate (AOT) and potassium hexacyanoferrate (II) (KHCF) in the medium. The aniline polymerization was confirmed by the detection of the absorption band typical of emeraldine salt at 420 nm, typical of the semiquinoid radical cation, and of the polaron absorption band at 700-800 nm, corresponding to the distinctive signal of doped or partial doped aniline. The oligomers and/or polymers obtained were characterized by spectrometry techniques, namely 1H NMR and MALDI-TOF, and the bacterial cellulose (BC) conductivity was assessed by means of a four-point probe electrical conductivity technique. The best polymerization results were obtained with 5 mM AOT, 10 mM KHCF, and 25 U/mL of laccase. The synergistic effect between both additives in the presence of a catalyst leads to obtaining BC samples coated with green polyaniline with promising electric conductive properties.
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Project description:Controlling the distribution of ionizable groups of opposite charge in microgels is an extremely challenging task, which could open new pathways to design a new generation of stimuli-responsive colloids. Herein, we report a straightforward approach for the synthesis of polyampholyte Janus-like microgels, where ionizable groups of opposite charge are located on different sides of the colloidal network. This synthesis approach is based on the controlled self-assembly of growing polyelectrolyte microgel precursors during the precipitation polymerization process. We confirmed the morphology of polyampholyte Janus-like microgels and demonstrate that they are capable of responding quickly to changes in both pH and temperature in aqueous solutions.
| S-EPMC6973257 | biostudies-literature
Project description:Laccase is a copper-containing polyphenol oxidase with a wide range of substrates, possessing a good application prospect in wastewater treatment and dye degradation. The purpose of this research is to study the degradation of various industrial dyes by recombinant laccase rlac1338 and the mutant enzyme lac2-9 with the highest enzyme activity after modification by error-prone PCR. Four enzyme activities improved mutant enzymes were obtained through preliminary screening and rescreening, of which lac2-9 has the highest enzyme activity. There are four mutation sites, including V281A, V281A, P309L, S318G, and D232V. The results showed that the expression of the optimized mutant enzyme also increased by 22 ± 2% compared to the unoptimized enzyme and the optimal reaction temperature of the mutant enzyme lac2-9 was 5°C higher than that of the rlac1338, and the optimal pH increased by 0.5 units. The thermal stability and pH stability of mutant enzyme lac2-9 were also improved. With ABTS as the substrate, the kcat/Km of rlac1338 and mutant strain lac2-9 are the largest than other substrates, 0.1638 and 0.618 s-1M-1, respectively, indicating that ABTS is the most suitable substrate for the recombinant enzyme and mutant enzyme. In addition, the Km of the mutant strain lac2-9 (76 μM) was significantly lower, but the kcat/Km (0.618 s-1M-1) was significantly higher, and the specific enzyme activity (79.8 U/mg) increased by 3.5 times compared with the recombinant laccase (22.8 U/mg). The dye degradation results showed that the use of rlac1338 and lac2-9 alone had no degradation effect on the industrial dyes [indigo, amaranth, bromophenol blue, acid violet 7, Congo red, coomassie brilliant blue (G250)], however, adding small molecular mediators Ca2+ and ABTS at the same time can significantly improve the degradation ability. Compared to the rlac1338, the degradation rates with the simultaneous addition of Ca2+ and ABTS of mutant enzyme lac2-9 for acid violet 7, bromophenol blue and coomassie brilliant blue significantly improved by 8.3; 3.4 and 3.4 times. Therefore, the results indicated that the error-prone PCR was a feasible method to improve the degradation activity of laccase for environmental pollutants, which provided a basis for the application of laccase on dye degradation and other environmental pollutants.
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Project description:Cyanobacteria are prokaryotic phototrophs capable of achieving high cellular densities with minimal inputs. These prokaryotic organisms can grow using sunlight as energy source and carbon dioxide as carbon source what makes them promising candidates as microbial cell factories for the production of numerous compounds such as chemicals, fuels, or biocatalysts. In this study, we have successfully designed and constructed using synthetic biology approach two recombinant strains of Synechococcus elongatus PCC7942 for heterologous expression of the industrially relevant Bacillus subtilis CotA laccase. One of the strains (PCC7942-NSI-CotA) was constructed through integration of the laccase gene into neutral site I of the cyanobacterial genome whilst the other (PCC7942-NSII-CotA) targeted neutral site II of the genome. Of the two strains the one with CotA laccase integrated in neutral site II (PCC7942-NSII-CotA) was superior in terms of growth rate and enzymatic activity toward typical laccase substrates: ABTS [2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonate)] and syringaldazine. That may suggest that two of the traditionally used neutral sites of S. elongatus PCC7942 are not equally suitable for the expression of certain transgenes. The PCC7942-NSII-CotA produced protein was capable of decolourising three classes of dyes namely: anthraquinonic-, azo-, and indigoid-type over 7 days of incubation making the strain a potentially useful microbial cell factory for the production of broad-spectrum biodegradation agent. Interestingly, presence of additional synthetic redox mediator ABTS had no effect on the degradation of these dyes.
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Project description:Laccases (EC 1.10.3.2) are a class of multi-copper oxidases that have industrial value. In the present study, forty-five isolates of wild mushrooms were screened for laccase production. Eight of the isolates exhibited exploitable levels of substrate oxidation capacity. Isolate BPSM10 exhibited the highest laccase activity of 103.50 U/ml. Internal Transcribed Spacer (ITS) rRNA gene sequencing was used to identify BPSM10 as Pleurotus pulmonarius. The response of BPSM10 to two nutritional media supplemented with various inducers was characterized and the results indicated that Malt Extract Broth (MEB) supplemented with Xylidine increased laccase production by 2.8× (349.5 U/ml) relative to the control (122 U/ml), while Potato Dextrose Broth (PDB) supplemented with xylidine increased laccase production by 1.9× (286 U/ml). BPSM10 has the ability to decolorize seven synthetic dyes in a liquid medium. Maximum decolorization was observed of malachite green (MG); exhibiting 68.6% decolorization at 100 mg/L. Fourier-transform infrared spectroscopy (FTIR) was employed to confirm the decolorization capacity. The present study indicates that P. pulmonarius BPSM10 has the potential to be used as a potent alternative biosorbent for the removal of synthetic dyes from aqueous solutions, especially in the detoxification of polluted water.
| S-EPMC6408733 | biostudies-literature