Phenolic Substrates Research Articles

Copper nanoparticles embedded fungal chitosan as a rational and sustainable bionanozyme with robust laccase activity for catalytic oxidation of phenolic pollutants.

Despite their potential for oxidation of persistent environmental pollutants, the development of rational and sustainable laccase nanozymes with efficient catalytic performance remains a challenge. Herein, fungal-produced chitosan-copper (CsCu) is proposed as a rational and sustainable bionanozyme with intrinsic laccase activity. The CsCu nanozyme was prepared by in situ reduction of copper on chitosan extracted from Irpex sp. isolate AWK2 a native fungus, from traditional fermented foods, yielding a low molecular weight chitosan with a 70% degree of deacetylation. Characterizations of the nanozyme using SEM-EDX, XRD, and XPS confirmed the presence of a multi-oxidation state copper on the chitosan matrix which is consistent with the composition of natural laccase. The laccase memetic activity was investigated using 2,4-DP as a substrate which oxidized to form a reddish-pink color with 4-AP (λmax = 510 nm). The CsCu nanozyme showed 38% higher laccase activity than the pristine Cu NPs at pH 9, indicating enhanced activity in the presence of chitosan structure. Further, CsCu showed significant stability in harsh conditions and exhibited a lower Km (0.26 mM) which is competitive with that reported for natural laccase. Notably, the nanozyme converted 92% of different phenolic substrates in 5 h, signifying a robust performance for environmental remediation purposes.

Spectroscopic characterization and the reactivity of a high valent (L)Cu(III) species supported by a proline-based pseudopeptide.

Inspired by copper-based metalloenzymes, we aim to incorporate amino acids into our ligands to facilitate active copper intermediates that serve as functional and structural models for these enzymes. Herein, we report the synthesis of a Cu(II) complex with a C2 symmetric proline-based pseudopeptide LH2 (N,N'-(ethane-1,2-diyl)bis(pyrrolidine-2-carboxamide)), which is capable of supporting an [(L)Cu(III)]+ (3) intermediate in MeOH : CH3CN (1 : 20) at -30 °C. From comparative studies with the pyridine analog Cu(II) complex, it was demonstrated that the incorporation of amino acid in the ligand framework decreased the Cu(III)/Cu(II) redox potential significantly to react readily with mCPBA and CAN. The newly generated [(L)Cu(III)]+ can promote hydrogen atom abstraction reactions with phenolic substrates.

EMERGÊNCIA DE SEMENTES E DESENVOLVIMENTO DE MUDAS DE ALFACE EM DIFERENTES SUBSTRATOS

INTRODUCTION: The production of lettuce seedlings is one of the most important steps in the production system. The substrate used in the production of lettuce seedlings plays a key role, and the quality depends on its physical structure and chemical composition. OBJECTIVE: Evaluate the effects of different substrates on germination and development of Verônica variety lettuce seedlings. METHODS: The experiment was carried out in Seedling Nursery Vale Verde, located in the municipality of Patrocínio, state Minas Gerais, Brazil, average altitude of 945 meters, geographic coordinates 18°54'14.4" south latitude and 46°59'40.9" west longitude. For this experiment, polystyrene trays were used. The experimental design was completely randomized, in a factorial scheme 3 x 1 x 7, and 28 seeds per plot, being considered for evaluation 12 seedlings of each plot. The substrates used were: phenolic foam, coconut fiber and compost. Data were subjected to analysis of variance and, subsequently, the means of treatments were subjected to multiple comparison analysis, by Tukey's test. RESULTS: There was a highly significant difference for emergence speed index, root size, leaf size, and significant difference for number of leaves. Germination, dry mass and green mass, on the other hand, did not show any significant difference. CONCLUSION: The phenolic foam substrate provided greater speed of emergence. The new world composite and coconut fiber substrate features a greater number of leaves and root size. The largest leaves and consequently the accumulation of green mass and dry mass were obtained in seedlings cultivated in the coconut fiber substrate. KEYWORDS: : emergency; hardwood; source; transplant; nursery.

Investigation of the effects of pesticides on 'Jonagold' apple (Malus x domestica) polyphenol oxidase enzyme activity

this study, the effects of a number of commonly used pesticides on the activity of the polyphenol oxidase (PPO) enzyme from pesticide-free and pesticide-applied 'Jonagold' apples were comparatively evaluated. Substrates 4-methylcatechol, pyrocatechol, pyrogallol and L-tyrosine were used to determine the substrate specificity of the PPO enzyme obtained from apple. According to the results, on the contrary, PPO enzyme from 'Jonagold' apple did not show any activity against L-tyrosine substrate which is a monophenolic substrate, the enzyme had high affinity against 4-methylcatechol, pyrocatechol and pyrogallol which are di and tri phenolic substrates. Km values of PPO enzyme obtained from pesticide-free apples against 4-methylcatechol, pyrocatechol, and pyrogallol substrates were determined as followed 0.27 mM, 2.27 mM, and 0.37 mM, respectively. Vmax values were found as 0.133 mM/min, 0.081 mM/min, and 0.051 mM/min. Optimum pH values were found to be 4.5 for 4-methylcatechol, 7.0 for pyrocatechol, and 7.5 for pyrogallol. Optimum temperature values were determined as 40 °C for 4-methylcatechol, 10 °C for pyrocatechol, and 50 °C for pyrogallol. Km values for PPO enzyme activity obtained from pesticide-treated apples against 4-methylcatechol, pyrocatechol, and pyrogallol substrates were 0.98 mM, 3.94 mM, and 0.37 mM, Vmax values were 0.08 mM/min, 0.02 mM/min, and 0.034 mM/min. Optimum pH values were found to be 7.0 for 4-methylcatechol and pyrocatechol and 7.5 for pyrogallol. Optimum temperature values were determined as 50 °C for 4-methylcatechol, 30 °C for pyrocatechol, and 40 °C for pyrogallol. Overall, the results showed that the PPO enzyme from pesticide-free apples had higher activity than pesticide-treated apples. The effects of metals and storage stability on PPO enzyme activity were also investigated. The results reveal that pesticide use affects PPO enzyme activity. The obtained data bring to light new pesticide functional features of great interest in the medicinal, agro-chemical and environmental circles.

Synthesis and Characterization of a Novel Resveratrol Xylobioside Obtained Using a Mutagenic Variant of a GH10 Endoxylanase.

Resveratrol is a natural polyphenol with antioxidant activity and numerous health benefits. However, in vivo application of this compound is still a challenge due to its poor aqueous solubility and rapid metabolism, which leads to an extremely low bioavailability in the target tissues. In this work, rXynSOS-E236G glycosynthase, designed from a GH10 endoxylanase of the fungus Talaromyces amestolkiae, was used to glycosylate resveratrol by using xylobiosyl-fluoride as a sugar donor. The major product from this reaction was identified by NMR as 3-O-ꞵ-d-xylobiosyl resveratrol, together with other glycosides produced in a lower amount as 4'-O-ꞵ-d-xylobiosyl resveratrol and 3-O-ꞵ-d-xylotetraosyl resveratrol. The application of response surface methodology made it possible to optimize the reaction, producing 35% of 3-O-ꞵ-d-xylobiosyl resveratrol. Since other minor glycosides are obtained in addition to this compound, the transformation of the phenolic substrate amounted to 70%. Xylobiosylation decreased the antioxidant capacity of resveratrol by 2.21-fold, but, in return, produced a staggering 4,866-fold improvement in solubility, facilitating the delivery of large amounts of the molecule and its transit to the colon. A preliminary study has also shown that the colonic microbiota is capable of releasing resveratrol from 3-O-ꞵ-d-xylobiosyl resveratrol. These results support the potential of mutagenic variants of glycosyl hydrolases to synthesize highly soluble resveratrol glycosides, which could, in turn, improve the bioavailability and bioactive properties of this polyphenol.

Oxygen versus Sulfur Coordination in Cobalt Superoxo Complexes: Spectroscopic Properties, O2 Binding, and H-Atom Abstraction Reactivity.

A five-coordinate, disiloxide-ligated cobalt(II) (S = 3/2) complex (1) was prepared as an oxygen-ligated analogue to the previously reported silanedithiolate-ligated CoII(Me3TACN)(S2SiMe2) (J. Am. Chem. Soc., 2019, 141, 3641-3653). The structural and spectroscopic properties of 1 were analyzed by single-crystal X-ray diffraction, electron paramagnetic resonance (EPR), and NMR spectroscopies. The reactivity of 1 with dioxygen was examined, and it was shown to bind O2 reversibly in a range of solvents at low temperatures. A cobalt(III)-superoxo complex, CoIII(O2·-)(Me3TACN)((OSi2Ph)2O) (2), was generated, and was analyzed by UV-vis, EPR, and resonance Raman spectroscopies. Unlike its sulfur-ligated analogue, complex 2 can thermally release O2 to regenerate 1. Vibrational assignments for selective 18O isotopic labeling of both O2 and disiloxide ligands in 2 are consistent with a 6-coordinate, Co(η1-O2·-)("end-on") complex. Complex 2 reacts with the O-H bond of 4-methoxy-2,2,6,6-tetramethylpiperidin-1-ol (4-MeO-TEMPOH) via H-atom abstraction with a rate of 0.58(2) M-1 s-1 at -105 °C, but it is unable to oxidize phenol substrates. This bracketed reactivity suggests that the O-H bond being formed in the putative CoIII(OOH) product has a relatively weak O-H bond strength (BDFE ∼66-74 kcal mol-1). These thermodynamic and kinetic parameters are similar to those seen for the sulfur-ligated Co(O2)(Me3TACN)(S2SiMe2), indicating that the differences in the electronic structure for O versus S ligation do not have a large impact on H-atom abstraction reactivity.

Characterization of Polyphenol Oxidase (PPO) from Blackberry Thorny Wild Rubus Fruticosus and its Inhibition using Natural Extracts

The Polyphenol oxidase (PPO) leads to the enzymatic browning of fruits and vegetables and needs to be prevented in food browning and quality. The present study aimed to investigate the use of natural extracts and chemical inhibitors to prevent browning of the PPO of blackberries. Purification, characterization, and kinetics of PPO of blackberry parameters for five substrates, namely, pyrocatechol, 4-methylcatechol, Pyrogallol, Gallic acid, and tyrosine, were described. The results showed that the DEAE-Sepharose and Superdex G-200 purification methods, which achieved electrophoretic purity, increased PPO activity by 556 fold. Purification with Sephadex GE-200 and SDS-PAGE reveals two PPO isoenzymes with an apparent molecular weight of 22 kD and 70 kD. The optimum pH and temperature values indicated were 6.6 and 25°C, respectively. The PPO showed variable affinity towards o-dihydroxy phenolic substrates with catecholase activity but without any activity observed with phenol, a monohydroxy substrate, and it was very effective towards pyrocatechol, pyrogallol, and 4-methyl catechol. The results revealed that inhibition of the PPO using both synthetic inhibitors and natural extracts was the most effective method. Quercetin and ascorbic acid showed higher inhibition with the lowest Ki values. Fresh onion (Allium cepa) and wild Arbutus unedo extract were able to inhibit the blackberry PPO activity up to 50% and 60%, respectively. Therefore, the use of natural extracts from Arbutus unedo L as anti-browning agents on the blackberry PPO may provide new insight to overcome the enzymatic browning.

Reactivity insights from the allylation of substituted phenols with 2-allyloxy-1-methylpyridinium triflate

Allyl phenyl ethers are efficiently formed by generating 2-allyloxy-1-methylpyridinium triflate in situ followed by reaction with a phenol substrate under mildly basic conditions. Electron-poor phenols give excellent yields of the corresponding allyl phenyl ether, while electron-rich phenols typically give more complicated crude reactions mixtures, and ultimately lower yields of isolated ether product. Interestingly, one of the critical factors for a successful reaction is the shape and size of the reaction vessel, potentially due to maximizing the surface area of the insoluble molten oxypyridinium salt and the rest of the reaction mixture. The addition of dibenzo-18-crown-6 helps the efficiency of the reaction, presumably by slightly improving the solubility of the reaction components. These reaction conditions indicate that both the nucleophilic and electrophilic components of these reactions are important for an efficient reaction, even though the mechanism of substitution has typically been described as “SN1-like.”

Investigation of Abortiporus biennis lignocellulolytic toolbox, and the role of laccases in polystyrene degradation

White-rot basidiomycetes are the only microorganisms able to produce both hydrolytic (cellulases and hemicellulases) and oxidative (ligninolytic) enzymes for degrading all lignocellulose constituents. Their enzymatic machinery makes them ideal for the discovery of novel enzymes with desirable properties. In the present work, Abortiporus biennis, a white-rot fungus, was studied in regard to its lignocellulolytic potential. Secretomics and biochemical analyses were employed to study the strain's enzymatic arsenal, after growth in corn stover cultures and xylose-based defined media. The results revealed the presence of all the necessary enzymatic activities for complete breakdown of biomass, while the prominent role of oxidative enzymes in the lignocellulolytic strategy of the strain became evident. Two novel laccases, AbiLac1 and AbiLac2, were isolated from the culture supernatant with ion-exchange chromatography. Characterization of purified laccases revealed their ability to oxidize a wide variety of phenolic and non-phenolic substrates. AbiLac1 was found to oxidize polystyrene powder, showing high depolymerization potential, based on radical chain scission mechanism as evidenced by molecular weight decrease. The results of the present study demonstrate the biotechnological potential of the unexplored enzymatic machinery of white-rot basidiomycetes, including the design of improved lignocellulolytic cocktails, as well as the degradation and/or valorization of plastic waste materials.

Diversification of phenolic glucosides by two UDP-glucosyltransferases featuring complementary regioselectivity

BackgroundGlucoside natural products have been showing great medicinal values and potentials. However, the production of glucosides by plant extraction, chemical synthesis, and traditional biotransformation is insufficient to meet the fast-growing pharmaceutical demands. Microbial synthetic biology offers promising strategies for synthesis and diversification of plant glycosides.ResultsIn this study, the two efficient UDP-glucosyltransferases (UGTs) (UGT85A1 and RrUGT3) of plant origin, that are capable of recognizing phenolic aglycons, are characterized in vitro. The two UGTs show complementary regioselectivity towards the alcoholic and phenolic hydroxyl groups on phenolic substrates. By combining a developed alkylphenol bio-oxidation system and these UGTs, twenty-four phenolic glucosides are enzymatically synthesized from readily accessible alkylphenol substrates. Based on the bio-oxidation and glycosylation systems, a number of microbial cell factories are constructed and applied to biotransformation, giving rise to a variety of plant and plant-like O-glucosides. Remarkably, several unnatural O-glucosides prepared by the two UGTs demonstrate better prolyl endopeptidase inhibitory and/or anti-inflammatory activities than those of the clinically used glucosidic drugs including gastrodin, salidroside and helicid. Furthermore, the two UGTs are also able to catalyze the formation of N- and S-glucosidic bonds to produce N- and S-glucosides.ConclusionsTwo highly efficient UGTs, UGT85A1 and RrUGT3, with distinct regioselectivity were characterized in this study. A group of plant and plant-like glucosides were efficiently synthesized by cell-based biotransformation using a developed alkylphenol bio-oxidation system and these two UGTs. Many of the O-glucosides exhibited better PEP inhibitory or anti-inflammatory activities than plant-origin glucoside drugs, showing significant potentials for new glucosidic drug development.

Operating diagrams for a three-tiered microbial food web in the chemostat.

In this paper, we consider a three-tiered food web model in a chemostat, including chlorophenol, phenol, and hydrogen substrates and their degraders. The model takes into account the three substrate inflowing concentrations, as well as maintenance, that is, decay terms of the species. The operating diagrams give the asymptotic behavior of the model with respect to the four operating parameters, which are the dilution rate and the three inflowing concentrations of the substrates. These diagrams were obtained only numerically in the existing literature. Using the mathematical analysis of this model obtained in our previous studies, we construct the operating diagrams, by plotting the curves that separate their various regions. Hence, the regions of the operating diagrams are constructed analytically and there is no requirement for time-consuming algorithms to generate the plots, as in the numerical method. Moreover, our method reveals behaviors that have not been detected in the previous numerical studies. The growth functions are of Monod form with the inclusion of a product inhibition term. However, our method applies for a large class of growth functions. We construct operating diagrams with and without maintenance showing the role of maintenance on the stability of the system.

Time-dependent electrochemical characteristics of a phenolic and non-phenolic compound in the presence of laccase/ABTS system.

The laccase/ABTS system has found several industrial applications ranging from biodeterioration to biodegradation and bioremediation. However, the capability of the laccase/ABTS system varies depending upon the type of substrate used. Voltammetric studies involving two widely used substrates, i.e., veratryl alcohol (VA) and alkali lignin (AL), were performed to gain new insight into the electrochemical behavior of the reactions. The individual electrochemical reactions established the differential nature of the two compounds over a concentration range, along with the mediator ABTS producing a distinguishing effect on their oxidative reactions, which was further studied over a 12hour period. It was followed by the reaction of both the compounds against the laccase/ABTS system that helped verify the role of the enzyme and the mediator in the electron transfer process and elucidate the mediated oxidations carried out by laccase against the phenolic and non-phenolic substrate through the process of cyclic voltammetry.

Changes of the gene expression in silkworm larvae and Cordyceps militaris at late stages of the pathogenesis

Cordyceps militaris is an entomopathogenic fungus that forms its fruiting body. The gene expression change in C. militaris and silkworm larvae were analyzed using RNA-seq to investigate the relationship of C. militaris with the host, silkworm larvae before the death by mycosis. At 144 h after the injection of C. militaris conidia, genes encoding proteases, protease inhibitors, and cuticle proteins in the fat body of silkworm larvae were upregulated, but genes encoding lipoproteins and other proteins in hemolymph were downregulated. On the other hand, at 168 h after the injection of C. militaris conidia, genes encoding amino acid and oligopeptide transporters and permeases in C. militaris were upregulated, suggesting that C. militaris may use peptides and amino acids in silkworm larvae as a nutrient to grow in vivo.Additionally, one gene cluster composed of genes putatively involved in the degradation of phenolic substrates was also upregulated. The addition of 4,5-dichlorocatechol, an inhibitor of catechol 1,2-dioxygenase, inhibited the in vivo growth of C. militaris, Beauveria bassiana and Metarhizium anisopliae. These results also suggest that the expression of the gene cluster may be crucial for the in vivo growth of C. militaris and entomopathogenic fungi. This study will clarify how C. militaris grows in insect hosts by avoiding host's immune systems.

Recent Advancements in Biotechnological Applications of Laccase as a Multifunctional Enzyme

Biotechnological and industrial processes involve applications of various microorganisms and enzymes, and laccase, as a multifunctional enzyme, is admired for its role in degrading a variety of substances. Laccase is a copper-containing oxidase enzyme that is usually found in insects, plants, and microorganisms including fungi and archaea. Several phenolic substrates are oxidized by laccases, which results in crosslinking. Various research work and industrial solutions have identified the true potential of laccases to degrade various aromatic polymers, and their plausible application in bioremediation and other industries is entirely conceivable. This review focuses on laccases as a multifunctional enzyme and provides an overview of its natural origin, catalytic mechanism, and various methods of production. Further, we discuss the various applications of laccase in the biotechnological arena. We observed that laccase can degrade and detoxify various synthetic compounds. The broad substrate specificity of the same makes it worthy for different fields of industrial applications such as food and bioremediation technology, textile and paper technology, biosensors and nanobiotechnology, biofuel, and various other applications, which are described in this paper. These recent developments in the application of laccase show the multifunctional role of laccase in industrial biotechnology and provide an outlook of laccase as a multifunctional enzyme at the forefront of biotechnology.

A Catalytic Asymmetric Pictet–Spengler Platform as a Biomimetic Diversification Strategy toward Naturally Occurring Alkaloids

Tetrahydroisoquinoline (THIQ) alkaloids constitute a large and diverse class of bioactive natural products, with the parent compounds and related downstream biosynthetic secondary metabolites spanning thousands of isolated structures. Chemoenzymatic synthetic approaches toward the relevant THIQs rely on Pictet–Spenglerases such as norcoclaurine synthase (NCS), the scope of which is strictly limited to dopamine-related phenolic substrates. To overcome these limitations in the context of chemical synthesis, we herein report asymmetric Pictet–Spengler reactions of N-carbamoyl-β-arylethylamines with diverse aldehydes toward enantioenriched THIQs. The obtained products proved to be competent intermediates in the synthesis of THIQ, aporphine, tetrahydroberberine, morphinan, and androcymbine natural products. Novel catalyst design with regard to the stabilization of cationic intermediates was crucial to accomplish high reactivity while simultaneously achieving unprecedented stereoselectivity for the reaction of biologically relevant substrates.

Enhancing SDS-PAGE Detection of Dilute Extracellular Polystyrene Degrading Enzymes Expressed by Bacillus megaterium Strain via Centrifugal Freeze Concentration Method

This study aims to enhance the sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) detection and visualization of extracellular polystyrene degrading enzyme expressed by Bacillus megaterium as a result of utilizing polystyrene as a sole carbon source. Dilute polystyrene degrading enzyme expressed in the culture supernatant could not be directly visualized from SDS-PAGE stained with colloidal Coomassie blue stain as it falls below its sensitivity or detection limit level. To overcome this problem, the crude enzyme extract was concentrated via the centrifugal freeze concentration method (cryoconcentration). The extracellular enzyme profiles were determined by SDS-PAGE. The SDS-PAGE analysis of the concentrated enzyme extract revealed 6 visible protein bands ranging in size from 10 to 60 kDa. Three distinct protein bands at approximately 20, 45 and 60 kDa were observed to be highly expressed in the culture supernatant. Polystyrene degrading enzyme extracted from the culture supernatant was closely related to several polymer degrading enzymes which suggest that the extracted enzyme from Bacillus megaterium also belongs to the hydrolase’s enzyme family. GC-MS analysis of the extracted samples significantly contains benzene derivatives due to the breaking down of the long-chain aromatic hydrocarbon polymer. Hydroxylation of the aromatic ring formed phenolic substrate took place which suggests being facilitated by intracellular enzyme hydroxylases. Hence, the biodegradation of polystyrene by Bacillus megaterium was believed to incorporate both intracellular and extracellular enzymes.
 HIGHLIGHTS
 
 Bacillus megaterium strain was first reported to contribute to polystyrene biodegradation
 Polystyrene degrading enzyme expressed by Bacillus megaterium was detected through SDS-PAGE
 Cryoconcentration enhanced SDS-PAGE protein detection
 The protein bands were most distinct visualized at approximately 20, 45 and 60 kDa by SDS-PAGE
 GC-MS analysis detected benzene derivatives which confirmed enzymatic degradation activity
 
 GRAPHICAL ABSTRACT

Horseradish Peroxidase-Catalyzed Coloration of Natural Phenols on Silk Fabric: Effects of Various Buffer Systems and pH Value on Dyed Color

ABSTRACT Currently, the known possible shades obtained for coloring silk fabrics using enzyme catalysts such as peroxidase are limited to a few shades of brownish tint. For the oxidative dyeing method using horseradish peroxidase (HRP) to become common, it must be able to produce a more diverse range of colors; this is a problem that must be solved. The purpose of this study is to obtain various colors by dyeing natural phenolic substrates using HRP in various buffers (acetate, citrate, phosphate buffer) and various pH levels (3 ~ 9). We emphasized color diversity, which was achieved through the exploration of six different natural aromatic compounds: gallic acid (GA), guaiacol (GAC), p-coumalic acid (CA), ferulic acid (FA), catechol (CAC) and caffeic acid (CFA). We also performed a methodological survey of reaction processing parameters. The colored products generated through HRP catalysis were analyzed using UV-vis. The color of the dyed fabrics was analyzed using the CIE L*a*b* color space system. As a result of the experiment, we obtained silk fabrics with various color depths from each buffer system. This suggests that the desired color and tone of dyed silk fabrics can be achieved by adjusting the buffer system and pH value.

Synthesis of intracellular polyhydroxyalkanoates (PHA) from mixed phenolic substrates in an acclimated consortium and the mechanisms of toxicity

Polyhydroxyalkanoates (PHA) are a class of intracellular storage polymers with the potential to supplement/replace petroleum-based plastics. Production of PHA from waste organics can reduce its cost, but toxic carbon sources such as simple aromatics are seldom used. This study investigates the feasibility of mixed toxic phenolics as substrates, utilizing a phenol-acclimated consortium of high PHA accumulation capability. Phenol was employed as the main feedstock, and four kinds of mono- and di-chlorinated phenols (CPs) were individually mixed with it as possible impurities. The inclusion of CPs was found to reduce substrate removal and PHA accumulation rates, compared to phenol alone. The degree of inhibition was positively-correlated with CP concentration, but the mechanisms differed. 2- and 3-chlorinated phenols formed dark, toxic, dead-end products; 4-chlorinated phenol (4-CP) appeared to exert competitive inhibition; and 2,4-dichlorinated phenol acted like an inert component. Transformation pathway study discovered that phenol was degraded via meta-cleavage, while 2- and 3-CPs were transformed into 3-chlorocatechol as the intermediate. FTIR, DSC, NMR, HPLC and elemental analysis were carried out to characterize the extracted polymer. The results show that phenol was converted to poly(3-hydroxybutyrate), while the inclusion of mono-chlorinated phenol promoted the production of PHA containing 3-hydroxyvalerate (3HV) monomers. A recovery test after mild CP exposure found that the affected biomass was able to resume phenol degradation and PHA synthesis immediately after simple aeration, indicating its robustness and applicability in a real industrial setting.

Transport and kinetics in an electroenzymatic process incurred in PPO-based rotating disk bioelectrodes

• A nonlinear system of equation arising in PPO-based rotating disc electrodes is studied. • The reliable and closed-form of expression of concentrations and current are obtained. • The effect of rotation rate on sensitivity and amplification factors is discussed. • Numerical and analytical results are compared for experimental values of parameters. The motivation for this work was to develop a theoretical analysis corresponding to the transport and kinetics of substrate and product in PPO-based rotating disk bioelectrodes. This model is based on a nonlinear reaction–diffusion system containing the nonlinear term related to the CEC' mechanism. The hyperbolic function approach was used to solve the nonlinear coupled system of reaction–diffusion equations. The approximate analytical expressions concentrations of phenol, catechol and o-quinone and current response for all possible diffusion and kinetic parameters values are reported. The bioelectrode's sensitivity and amplification factor towards phenol substrate were also presented in terms of rotation rate and enzyme layer thickness. The numerical solution of this problem is also reported using Scilab/Matlab program. Also, a satisfactory agreement is noted between the analytical and numerical results upon comparison.

Biotechnological Applications of Manganese Peroxidases for Sustainable Management

Microbial manganese peroxidases (MnPs) are ligninolytic enzymes primarily responsible for degrading lignin, but they are also capable of degrading dyes, organic pollutants, and emerging contaminants in wastewater. They have been isolated and characterized from many white-rot fungi and few bacteria. For microbial MnPs, the optimum pH range is between 3.5 and 9.0; the optimum temperature range is between 25°C and 70°C. Their molecular weights range between 25 kDa and 68 kDa. By oxidizing Mn2+ to Mn3+, they can oxidize a wide range of phenolic and non-phenolic substrates. MnPs can be used in a wide range of industrial applications, including delignification of pulp, wastewater treatment, biofuel production, dye removal, biopulping, biobleaching, and juice extract clarification. The purpose of this review is to summarize biotechnological applications of manganese peroxidases.