Rhizopus rot of peach fruits could be significantly suppressed by Pichia membranefaciens. Polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonium-lyase (PAL) activities induced by inoculation with P. mem...Rhizopus rot of peach fruits could be significantly suppressed by Pichia membranefaciens. Polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonium-lyase (PAL) activities induced by inoculation with P. membrane faciens or R. stolonifer were studied in postharvest peach fruits. The activities of PPO and PAL in peaches increased significantly after being inoculated with P. membrane faciens + R. stolonifer by 24 h, the activities maintained at a high level throughout the experiment. Under the condition of infected with R. stolonifer alone, activity of PPO and PAL could also increased, but the levels were lower than those treated with P. membrane faciens+ R. stolonifer. However, fruits inoculaed with P. membrane-faciens + R. stolonifer or R. stolonifer alone did not stimulated POD activity. The results suggest that the activation of these defense enzymes is involved in the action of P. membrane faciens against R. stolonifer.展开更多
In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries....In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.展开更多
To study insecticidal mechanism of terpinen-4-ol, a main insecticidal composition in the essential oil of Sabina vulgaris, the 5th instar larvae of Mythimna separta, were investigated with terpinen-4-ol by topical app...To study insecticidal mechanism of terpinen-4-ol, a main insecticidal composition in the essential oil of Sabina vulgaris, the 5th instar larvae of Mythimna separta, were investigated with terpinen-4-ol by topical application. The activities of phosphatase, glutathione S-transferase （GSTs）, cytochrome P450 （P450）, and polyphenol oxidase （PPO） of tested insects were determined in all poisoning stages, including exciting stage, convulsing stage, paralysis stage, and recover stage. The result showed that the activities of both acid phosphatase （ACP） and alkaline phosphatase （AKP） in treated insects were induced by terpinen-4-ol, but ACP was inhibited in paralysis stage. The activities of GSTs were inhibited in exciting stage, convulsing stage, and paralysis stage, but gradually recovered in recover stage. O-demethylase activity of cytochrome P450 was inhibited by terpinen-4-ol, and the inhibition rate in all poisoning stages were 26.27, 46.03, 80.24, and 90.22%, respectively. PPO activities were strongly inhibited by terpinen-4-ol both in vitro and in vivo. In conclusion, the activities of P450, GSTs, and PPO could have relation with toxicity of terpinen-4-ol against larvae of the Mythimna separta, but recover stage of the poisoning insects might be related to GSTs induced. As a new insecticide or synergist, terpinen- 4-ol has a potential value in field of insecticide resistance management.展开更多
[Objective] This study aimed to investigate the enzymatic kinetics of polyphenol oxidase in peel of Nephelium lappaceum to explore the environmental factors affecting its catalytic activity. [ Method ] With N. lappace...[Objective] This study aimed to investigate the enzymatic kinetics of polyphenol oxidase in peel of Nephelium lappaceum to explore the environmental factors affecting its catalytic activity. [ Method ] With N. lappaceum peel as the experimental material and catechol as substrate, effects of temperature, pH, four inhibitors （EDTA, Vc, sodium bisulfite and citric acid） and substrate concentration on the activity of polyphenol oxidase were investigated. [ Result] The optimal temperature for polyphenol oxidase in N. lappaceum peel was 40 %, and the optimal pH was 6.8. EDTA, Vc, sodium bisulfite and citric acid all showed ideal in- hibitory effects on the activity of polyphenol oxidase; specifically, EDTA had the strongest inhibitory effect. [ Conclusion] At low temperature, EDTA, Vc, sodi- um bisulflte and citric acid with certain concentrations can inhibit the catalytic activity of polyphenol oxidase in peel of N. lappaceum, extend the storage and trans- portation time of N. lappaceum fruit, and inhibit the browning. This study provides theoretical basis for the development and utilization of polyphenol oxidase in peel of N. lappaceum.展开更多
Polyphenol oxidase, a bi-functional enzyme, has been implicated in enzymatic browning of yam and other tubers in a negative way. The objective of this present study was to examine the activity of polyphenol oxidase in...Polyphenol oxidase, a bi-functional enzyme, has been implicated in enzymatic browning of yam and other tubers in a negative way. The objective of this present study was to examine the activity of polyphenol oxidase in Dioscorea rotundata. Var. laasirin and the efficiency of heat and chemical treatments in inhibiting this enzyme. Crude Polyphenol Oxidase （PPO） of Dioscorea rotundata.Var. Laasirin was isolated and the kinetics studied using the lineweaver-burk plot. The activity of the enzyme was evaluated using spectrophotomeric method. Yam PPO catalyzes oxidation of various substrates with catechol being the most readily oxidized substrate. The Michaelis-Menten constant （Km） and maximum reaction velocity （Vmax） for yam PPO were 0.00037 and 0.3125 respectively. Inhibition data showed that the enzyme had least activity （71.70） when blanched at 95℃ for 7 mins with chemical treatment involving a combination of 0.5% Sodium metabisulphite （Food grade） and 0.5% Ascorbic acid （Food grade）. The activity was highest （83.02） when it was blanched at 95 ℃ for 7 rains. This study has shown that it is possible to inhibit polyphenol oxidase activity in white yam using the chemical pretreatments and processing conditions described in this study for possible adoption in the production of packaged frozen yam chips by food industries.展开更多
[Objectives]This study was conducted to investigate the effects of embedding conditions on activity and catalytic properties of immobilized polyphenol oxidase.[Methods]Polyphenol oxidase was immobilized in a polymer m...[Objectives]This study was conducted to investigate the effects of embedding conditions on activity and catalytic properties of immobilized polyphenol oxidase.[Methods]Polyphenol oxidase was immobilized in a polymer material by the embedding method,and the optimal immobilization conditions were obtained by single factor tests:CaCl_(2) concentration 2.0%,sodium alginate concentration 2.0%,immobilization time 2 h and mass ratio of enzyme to carrier 10 mg/100 g,under which the immobilized enzyme activity was 93.33 U/g.Under the above conditions,the properties of polyphenol oxidase immobilized by sodium alginate(A-PPO)and free polyphenol oxidase were studied.[Results]The thermostability of A-PPO was better than that of the free enzyme,but the pH stability of A-PPO was inhibited.The Michaelis constant K_(m) values of free polyphenol oxidase and A-PPO were 0.37 and 0.48 mmol/L,respectively,and the maximum reaction rate V_(max) values were 0.38 and 0.51 mmol/(L·g),respectively.[Conclusions]This study provides a theoretical basis for the study of the properties of polyphenol oxidase.展开更多
The effects of radiofrequency(RF)heating on the activity,structure,and surface hydrophobicity of mushroom polyphenol oxidase(PPO)were examined and four kinetic models of inactivation(First-order model,Weibull model,Lo...The effects of radiofrequency(RF)heating on the activity,structure,and surface hydrophobicity of mushroom polyphenol oxidase(PPO)were examined and four kinetic models of inactivation(First-order model,Weibull model,Logistic model and Bi-phasic model)were fitted.The results demonstrated that RF heating could effectively inactivate PPO,logistic and Bi-phasic model attained the best fit.The circular dichroism(CD)and fluorescence spectroscopy spectra revealed that RF heating at 65℃ for 180 s caused changes in the secondary and tertiary structures of PPO,reducing the α-helix content from 38.5% to 30.3% and red-shifting the emission peak wavelength of the maximum fluorescence intensity from 318 nm to 321 nm.RF heating also caused a significant enhancement of the surface hydrophobicity of the PPO(P<0.05).The color test results showed that RF heating could inhibit the browning of mushrooms(P<0.05).Thus,RF heating is an effective technique for the inactivation of enzymes and further research should be performed on RF heating applications to inactivate enzymes in the food industry.展开更多
Enzymatic browning,primarily driven by polyphenol oxidase(PPO),poses a significant challenge in maintaining food quality and consumer acceptance across various sectors.This review critically examines available data on...Enzymatic browning,primarily driven by polyphenol oxidase(PPO),poses a significant challenge in maintaining food quality and consumer acceptance across various sectors.This review critically examines available data on corn silk(Stigma maydis),an agro-industrial byproduct rich in antioxidant flavonoids(such as luteolin,apigenin,and formononetin),phenolic acids,and active carbohydrates.The gathered evidence indicates that corn silk compounds could effectively reduce PPO activity in both plant-derived and bacterial systems,suggesting they can mitigate browning through mechanisms that include direct enzyme inhibition and structural modulation of PPO’s biophysical properties.In vitro studies further reveal that corn silk extracts enhance radical-scavenging activity and may offer antimicrobial benefits,thus contributing to improved food stability.Although promising applications range from fresh-cut produce treatments to incorporation into edible coatings and functional beverages,further research is required to optimize extraction methods,achieve formulation stability,and comprehensively assess sensory impacts and consumer acceptance.Overall,the reviewed research positions corn silk as a promising candidate for developing effective,safe,and environmentally friendly preservation strategies,while also highlighting the need for a multidisciplinary approach to fully integrate this natural resource into modern food systems.展开更多
Polyphenol oxidase(PPO)is the main enzyme initiating internal browning in peach fruit stored at low tem-perature.Previous studies showed fatty acids activated PPO,but its specific effect and mechanism of activation on...Polyphenol oxidase(PPO)is the main enzyme initiating internal browning in peach fruit stored at low tem-perature.Previous studies showed fatty acids activated PPO,but its specific effect and mechanism of activation on PPO are still not clear.Thus,the effects of fatty acids on the biochemical properties and structural confor-mation of PPO were studied,with sodium dodecyl sulfate used as comparison.The highest degree of activation(5 folds)of membrane-bound PPO(mPPO)was found with 2.2 mM linoleic acid(LA)and its optimal activity was observed also around pH 7.0.Further structure analysis showed LA led to an increase ofα-helix content of mPPO from 23.53%to 52.33%;the maximum emission wavelength of treated mPPO shifted from 338 to 340 nm with the fluorescence intensity increased from 446 to 510.LA also can form hydrogen bonds and hydrophobic in-teractions with mPPO.These results indicated that LA could contribute to a more stable and open enzyme structure,thus activated mPPO.The results will provide more information for PPO activation that highly probably occurs in postharvest peach fruit and its relationship with internal browning.展开更多
In this study,ergothioneine liposomes were prepared via the reverse evaporation method,and the preparation conditions were optimized by single-factor experiments and response surface methodology.The optimal prep-arati...In this study,ergothioneine liposomes were prepared via the reverse evaporation method,and the preparation conditions were optimized by single-factor experiments and response surface methodology.The optimal prep-aration conditions were determined as follows:the pH of the aqueous phase was 7.1,the ratio of membrane materials(soy lecithin:cholesterol)was 3.5:1,and the ratio of lipids to the drug(soy lecithin:ergothioneine)was 28:1,with an encapsulation efficiency of 77.6%.The prepared liposomes were characterized by uniform particle size and good stability,while retaining the antioxidant activity of ergothioneine.Subsequently,polyphenol oxidase(PPO)was extracted and purified from Lanzhou lily.The inhibitory effect of ergothioneine(EGT)on the PPO activity in lily bulbs was investigated by means of fluorescence spectroscopy,circular dichroism spectros-copy and other techniques.Fluorescence results showed that ergothioneine quenched the endogenous fluores-cence of PPO from Lanzhou lily through a static quenching mechanism.The formed complex was mainly stabilized by hydrophobic interactions,and this process only induced local conformational changes of the enzyme protein.Finally,storage experiments demonstrated that chitosan-modified ergothioneine liposomes effectively delayed the browning of lily bulbs.This study not only elucidated the core mechanism underlying the inhibition of lily PPO by ergothioneine,but also successfully prepared highly efficient and stable ergothioneine liposomes.It provides a natural preservation solution for Lanzhou lily and other similar browning-prone fruits and vegetables,and also offers a theoretical reference for the development of natural browning inhibitors and the application of liposomes in the storage of fruits and vegetables.展开更多
Pinus elliottii oleoresin(PEO)is a renewable feedstock for producing rosin and turpentine,yet storage-induced enzymatic browning can markedly impair the color quality of PEO and downstream rosin products.Rosin-derived...Pinus elliottii oleoresin(PEO)is a renewable feedstock for producing rosin and turpentine,yet storage-induced enzymatic browning can markedly impair the color quality of PEO and downstream rosin products.Rosin-derived materials are used in food-related products,including beverage emulsions and food-contact pack-aging;therefore,maintaining color stability is important for both consumer acceptance and commercial value.In this study,enzymatic browning in wet-stored PEO was linked to the leaching of phenolics from impurity pine needles into the aqueous phase.Polyphenol oxidase(PPO)was extracted from Pinus elliottii needles and char-acterized.The enzyme showed maximal activity at pH 7.0 and 35℃ and retained more than 80%activity over pH 6.5-7.5.Thermal deactivation kinetics indicated that the enzyme is heat sensitive.The enzyme exhibited high affinity toward epicatechin(Km=5.93 mM).A PEO browning model based on epicatechin was established,and the Weibull model accurately described browning development,supporting enzymatic browning as a key contributor to color deterioration during storage.L-cysteine(L-Cys)was evaluated as an antibrowning agent and showed a mixed inhibition pattern in kinetic assays;fluorescence spectroscopy and molecular docking suggested that its interaction with the enzyme is mainly stabilized by hydrogen bonding and hydrophobic contacts.Overall,this work clarifies the biochemical origin of oleoresin discoloration and provides a mechanistic basis for miti-gating rosin darkening during storage.展开更多
To address color deterioration and nutrient loss during goji berry drying,this study proposes an innovative process combining acidic electrolyzed water(AEW)pretreatment with pulsed vacuum drying(PVD).Through systemati...To address color deterioration and nutrient loss during goji berry drying,this study proposes an innovative process combining acidic electrolyzed water(AEW)pretreatment with pulsed vacuum drying(PVD).Through systematic evaluation of drying characteristics,color,total phenolic content(TPC),total flavonoid content(TFC),total carotenoid content(TCC),antioxidant activity,browning index(BI),lipid oxidation degree,and polyphenol oxidase(PPO)activity,combined with fitting the PPO thermal inactivation pattern using first-order kinetic models and logistic models,and utilizing scanning electron microscopy(SEM),intrinsic fluorescence spectros-copy,and Fourier transform infrared spectroscopy(FTIR)techniques,the mechanisms of color retention and enzyme inhibition were comprehensively elucidated at the microstructural and protein conformation levels.Results indicate that AEW pretreatment effectively disrupts the wax layer on goji berries,significantly enhancing drying rate.The AEW30s treatment group demonstrated optimal overall performance,better preserving TPC,TFC,and TCC while reducing the browning index by 30.42%and significantly inhibiting lipid oxidation.Kinetic fitting of PPO inactivation revealed the Logistic model exhibited the highest goodness-of-fit(R^(2)>0.96),pre-dicting the lowest residual PPO activity in the AEW30s group,reduced by 15.4%compared to the control.Structural analysis indicated that AEW irreversibly inactivated PPO by disrupting its spatial conformation,manifested as quenching of endogenous fluorescence and decreased fluorescence intensity of tryptophan resi-dues.This study revealed the color-preserving mechanism of AEW combined with pulse vacuum drying from multiple perspectives,providing a theoretical basis for developing high-quality,sustainable goji berry drying technologies.展开更多
In this study, the kinetics of inhibition of polyphenol oxidase by L-cysteine has been investigated. The inhibition of tobacco polyphenol oxidase was studied using the progress-of-substrate-reaction method proposed by...In this study, the kinetics of inhibition of polyphenol oxidase by L-cysteine has been investigated. The inhibition of tobacco polyphenol oxidase was studied using the progress-of-substrate-reaction method proposed by Tsou, following the substrate reaction during irreversible inhibition of the enzyme activity. Analysis of the inhibition kinetics shows that inhibition occurs by an irreversible and non-complexation reaction. The microscopic rate constants were determined for reaction of the inhibitor both with the free enzyme and with the enzyme-substrate complex. The results show that the presence of the substrate has a significant protective effect of the enzyme against inactivation by L-cysteine.展开更多
Yellowing even browning of radish commonly occurred during the traditional pickling.This research aimed to determine the reason of yellowing of pickled radish,and propose the method for yellowing inhibition.The activi...Yellowing even browning of radish commonly occurred during the traditional pickling.This research aimed to determine the reason of yellowing of pickled radish,and propose the method for yellowing inhibition.The activity of endogenous enzymes in radish were analyzed,and the relationship between the activity and the browning was investigated.Myrosinase and polyphenol oxidase(PPO)were found as main potential enzymes resulting in browning of radish.During traditional salting processing,the myrosinase activity decreased,particularly at a high speed in the first 14 days,while the PPO activity did not decrease observably.The a*and b*values of salted radish were significantly correlated with myrosinase and PPO activity.Acid treatment was observed to be effective for browning inhibition of radish during soaking and storage,and the low pH conditions contributed to the preservation of original green color of radish.Stronger acidification during the first 3 d played a much more important role in browning inhibition than following weaker acidification treatment for 27 d.Low pH showed an inhibition effect on PPO activity,but myrosinase reactivity was more sensitive to pH changes than PPO.The myrosinase in the radish treated in the pickling solution at pH 2 was completely inactivated during the first 3 days.Further investigation of pH effect on improvement of salted radish color concluded that pH 2.4 was the optimal pH for the inactivation of myrosinase and PPO.Accordingly,short-term accurate acidification coupled with traditional salting treatment was originally proposed for effective browning inhibition of pickled radish.展开更多
Polyphenol oxidase （PPO） is the enzyme responsible for enzymatic browning during the growth of insects. It is also involved in defense reactions and is related with immunities in insects. PPO a metalloenzyme oxidase...Polyphenol oxidase （PPO） is the enzyme responsible for enzymatic browning during the growth of insects. It is also involved in defense reactions and is related with immunities in insects. PPO a metalloenzyme oxidase, catalyzes the oxidation of o-diphenol to o-quinone. The present paper describes the effects of benzaldehyde and its p-substituted derivatives on the activity of PPO from the fifth instar of Pieris rapae L. PPO from the fifth instar of Pieris rapae L. was purified using ammonium sulfate fractionation and chromatography on Sephadex G-100. The enzyme kinetics was characterized using L-3,4-dihydroxyphenylalanine （L-DOPA） as substrate. The results show that benzaldehyde, phydroxybenzaldehyde, p-chlorobenzaldehyde, and p-cyanobenzaldehyde can inhibit the PPO activity for the oxidation of L-DOPA. The inhibitor concentration leading to 50% activity lost, IC50, was estimated to be 5.90, 5.62, 2.83, and 2.91 mmol/L for the four tested inhibitors, respectively. Kinetic analyses show that the inhibitory effects of these compounds are reversible. Benzaldehyde, phydroxybenzaldehyde, and p-chlorobenzaldehyde are noncompetitive inhibitors while p-cyanobenzaldehyde is a mixed-type inhibitor. The inhibition constants were determined for all four inhibitors. p-chlorobenzaldehyde and p-cyanobenzaldehyde were more potent inhibitors than the other compounds. These results provide a basis for developing PPO inhibition-based pesticides.展开更多
The harvested loquat fruits are prone to browning,leading to a decline in fruit quality.Inhibiting activity of polyphenol oxidase(PPO)is an important way to prevent browning.In this study,we evaluated the inhibitory i...The harvested loquat fruits are prone to browning,leading to a decline in fruit quality.Inhibiting activity of polyphenol oxidase(PPO)is an important way to prevent browning.In this study,we evaluated the inhibitory impact of oligomeric procyanidins(OPC)on hydroxylation of monophenol and oxidation of o-diphenol catalyzed by PPO and effect of OPC on loquat fruits storage.The obtained results revealed that OPC could attenuate the activity of monophenolase and diphenolase.For monophenolase activity,the inhibition rate was observed to be dose-dependent with an IC50 of 11.6±3.4μg/mL for the steady-state rate.For diphenolase activity,OPC inhibited PPO activity(IC50=15.75±2.1μg/mL)with a reversible and competitive mechanism and quenched fluorescence of PPO by forming OPC-PPO complex with one binding site in a static procedure.In addition,the data obtained from storage assays revealed that OPC could enhance the quality of harvested loquat fruits by attenuating the PPO activity,augmenting the content of total phenolics and flavonoids,and simultaneously delaying the browning of loquats.In this research,we identified a potent PPO inhibitor and expanded its potential as a food preservative.展开更多
Polyphenolic compound in processing apple （Malus domestica Borkh.） varieties and the relationship between polyphenol content and enzymatic browning were studied to provide reference for raw material selection and pr...Polyphenolic compound in processing apple （Malus domestica Borkh.） varieties and the relationship between polyphenol content and enzymatic browning were studied to provide reference for raw material selection and processing method optimization. The content of polyphenol compound in 10 processing apple varieties （4 cider and 6 juice varieties） were analyzed using the Folin-Ciocalteu method and HPLC. The degree of browning and the activities of polyphenol oxidase were also studied. The content and proportion of the polyphenol varied depending on the variety. Bitter varieties globally showed a higher polyphenol concentration than sweet or acid varieties. Proanthocyanidins, chlorogenic acid, （＋）-catechin, （-）-epicatechin were high-concentrated polyphenols in apple fruits. Phloridzin, the unique polyphenol of apple, was abundant in the bitter variety Frequin rouge fruit. Total polyphenols, proanthocyanidins, （＋）-catechin, and phloridzin had higher correlations with browning. The correlation was low between chlorogenic acid and browning. The polyphenolic profiles were correlated with the apple types. Cider apples contained more polyphenol than juice apple varieties. The content of flavan-3-ol has a close relationship with fruit browning.展开更多
Elevation affects the contents of polyphenols involved in the plants’resistance to the environment.In this study,polyphenolic contents,as well as the activity of polyphenol oxidase(PPO),were evaluated in mature cigar...Elevation affects the contents of polyphenols involved in the plants’resistance to the environment.In this study,polyphenolic contents,as well as the activity of polyphenol oxidase(PPO),were evaluated in mature cigar plants at different elevation levels.The results showed that:(1)The contents of chlorogenic acid,rutin,and scopolamine in cigar leaves increased gradually at all elevation levels,reaching a maximum 25 d after the mature stage.(2)With an increase in altitude,the polyphenolic compounds’contents increased,having the lowest values at 350 m height and the highest at 1090 m height.(3)As for the PPO activity in cigar leaves,the general trend showed an increase first followed by a decrease in activity during the mature period.(4)PPO activity in the leaves of cigar plants planted at 840 m height was substantially elevated compared to those growing at 600 m and 350 m height.Interestingly,the leaves planted at 1090 m height had the lowest PPO activity.(5)There were significant positive correlations between altitude and the contents of chlorogenic acid,rutin,and scopolamine within the plants leaves.Altitude negatively correlated the proportion of chlorogenic acid and scopolamine whereas positively correlated rutin proportion within the total polyphenols.Temperature had negative correlations with the contents of chlorogenic acid,rutin,and scopolamine,while sunlight intensity had positive correlations on their contents.Conversely,there were no significant correlations between altitude,temperature,and light intensity on PPO activity.Therefore,this study can provide valuable insight and a theoretical basis for the production of premium cigars.展开更多
Paper and pulp mills generate substantial volumes of wastewater containing lignin-derived compounds that are challenging to degrade using conventional wastewater treatment methods.This study presents a novel biofilm-b...Paper and pulp mills generate substantial volumes of wastewater containing lignin-derived compounds that are challenging to degrade using conventional wastewater treatment methods.This study presents a novel biofilm-based process for enhanced lignin removal in wastewater using the fungus Neurospora discreta,which effectively degrades lignin and forms robust biofilms at the air–liquid interface under specific conditions.The process was optimised using the Taguchi design of experiments approach,and three factors including pH,copper sulphate concentration,and trace element concentration were evaluated at three levels.Experimental data were analysed against three responses:lignin degradation efficiency and the activities of two ligninolytic enzymes(polyphenol oxidase and versatile peroxidase).The results indicated that wastewater pH was the most significant parameter affecting lignin degradation efficiency and enzyme activities.Over 70%lignin degradation was achieved at pH levels of 5 and 6 with copper sulphate concentrations above 4 mg/L,while degradation efficiency drastically dropped to 45%at a pH value of 7.Reversed-phase high-performance liquid chromatography analysis demonstrated the effects of the three factors on the polar and non-polar components of lignin in wastewater,revealing a clear decrease in all peak areas after treatment.Additionally,significant relationships were observed between biofilm properties(including porosity,water retention value,polysaccharide content,and protein content)and lignin removal efficiency.This study also reported for the first time the presence of versatile peroxidase,a ligninolytic enzyme,in Neurospora sp.展开更多
[Objective] This study aimed to explore the effects of treatments with three types of exogenous oxidase solutions and H2O2.solution on the somatic embryogenesis of Fraxinus mandshurica Rupr. （Oleaceae）. [Method] The...[Objective] This study aimed to explore the effects of treatments with three types of exogenous oxidase solutions and H2O2.solution on the somatic embryogenesis of Fraxinus mandshurica Rupr. （Oleaceae）. [Method] The immature zygotic cotyledons were treated with PPQ （polyphenol oxidase） solution, GQD （glucose oxidase） solution, SOD （superoxide dismutase） solution and H202 （hydrogen peroxide） at different concentrations to explore the effects on the growth, browning and somatic embryogenesis on cotyledon explants in the somatic embryogenesis of F. mandshurica. Through comparative analysis on the effects of different treatments on somatic embryogenesis of F. mandshurica, the relationship between explants browning and somatic embryogenesis was uncovered during the somatic embryogenesis of F. mandshurica. [Result] H2O2 treatment not only advanced the explants browning, but also inhibited the growth and somatic embryogenesis of explants; different concentrations of PPQ promoted the growth and browning of explants, as well as improving the incidence of somatic embryogenesis; both GOD and SOD treatment could raise the explants browning rate; when somatic embryogenesis of explants treated with enzyme solutions advanced, the incidence of somatic embryogenesis was low; however, when the disparity of the incidence of somatic embryogenesis between 30 and 60 d treatments reached its peak, the incidence of somatic embryogenesis was also high. [Conclusion] The results of this study provide basis for raising the incidence and improving the status of somatic embryogenesis of F. mandshurica, as well as optimizing the somatic embryogenesis system of F. mandshurica.展开更多
基金the grants fromthe National Natural Science Foundation of China(NNSF-30170663) the Chinese Academy of Sciences.
文摘Rhizopus rot of peach fruits could be significantly suppressed by Pichia membranefaciens. Polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonium-lyase (PAL) activities induced by inoculation with P. membrane faciens or R. stolonifer were studied in postharvest peach fruits. The activities of PPO and PAL in peaches increased significantly after being inoculated with P. membrane faciens + R. stolonifer by 24 h, the activities maintained at a high level throughout the experiment. Under the condition of infected with R. stolonifer alone, activity of PPO and PAL could also increased, but the levels were lower than those treated with P. membrane faciens+ R. stolonifer. However, fruits inoculaed with P. membrane-faciens + R. stolonifer or R. stolonifer alone did not stimulated POD activity. The results suggest that the activation of these defense enzymes is involved in the action of P. membrane faciens against R. stolonifer.
文摘In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.
基金supported by the National Natural Science Foundation of China(30600404)the Key Technologies R&D Program of China during the 10th Five-Year Plan Period(2004BA516A04).
文摘To study insecticidal mechanism of terpinen-4-ol, a main insecticidal composition in the essential oil of Sabina vulgaris, the 5th instar larvae of Mythimna separta, were investigated with terpinen-4-ol by topical application. The activities of phosphatase, glutathione S-transferase （GSTs）, cytochrome P450 （P450）, and polyphenol oxidase （PPO） of tested insects were determined in all poisoning stages, including exciting stage, convulsing stage, paralysis stage, and recover stage. The result showed that the activities of both acid phosphatase （ACP） and alkaline phosphatase （AKP） in treated insects were induced by terpinen-4-ol, but ACP was inhibited in paralysis stage. The activities of GSTs were inhibited in exciting stage, convulsing stage, and paralysis stage, but gradually recovered in recover stage. O-demethylase activity of cytochrome P450 was inhibited by terpinen-4-ol, and the inhibition rate in all poisoning stages were 26.27, 46.03, 80.24, and 90.22%, respectively. PPO activities were strongly inhibited by terpinen-4-ol both in vitro and in vivo. In conclusion, the activities of P450, GSTs, and PPO could have relation with toxicity of terpinen-4-ol against larvae of the Mythimna separta, but recover stage of the poisoning insects might be related to GSTs induced. As a new insecticide or synergist, terpinen- 4-ol has a potential value in field of insecticide resistance management.
基金Supported by Leading Academic Discipline Project of Botany in Guizhou Province ([2011] No.275)College-level Planning Project of Kaili University(Z0804)+1 种基金Leading Academic Discipline Project of Botany from Kaili University (KZD2008002)Construction Project for Basic Course Teaching Team of Biological Science from Kaili University (JXTD201003)
文摘[Objective] This study aimed to investigate the enzymatic kinetics of polyphenol oxidase in peel of Nephelium lappaceum to explore the environmental factors affecting its catalytic activity. [ Method ] With N. lappaceum peel as the experimental material and catechol as substrate, effects of temperature, pH, four inhibitors （EDTA, Vc, sodium bisulfite and citric acid） and substrate concentration on the activity of polyphenol oxidase were investigated. [ Result] The optimal temperature for polyphenol oxidase in N. lappaceum peel was 40 %, and the optimal pH was 6.8. EDTA, Vc, sodium bisulfite and citric acid all showed ideal in- hibitory effects on the activity of polyphenol oxidase; specifically, EDTA had the strongest inhibitory effect. [ Conclusion] At low temperature, EDTA, Vc, sodi- um bisulflte and citric acid with certain concentrations can inhibit the catalytic activity of polyphenol oxidase in peel of N. lappaceum, extend the storage and trans- portation time of N. lappaceum fruit, and inhibit the browning. This study provides theoretical basis for the development and utilization of polyphenol oxidase in peel of N. lappaceum.
文摘Polyphenol oxidase, a bi-functional enzyme, has been implicated in enzymatic browning of yam and other tubers in a negative way. The objective of this present study was to examine the activity of polyphenol oxidase in Dioscorea rotundata. Var. laasirin and the efficiency of heat and chemical treatments in inhibiting this enzyme. Crude Polyphenol Oxidase （PPO） of Dioscorea rotundata.Var. Laasirin was isolated and the kinetics studied using the lineweaver-burk plot. The activity of the enzyme was evaluated using spectrophotomeric method. Yam PPO catalyzes oxidation of various substrates with catechol being the most readily oxidized substrate. The Michaelis-Menten constant （Km） and maximum reaction velocity （Vmax） for yam PPO were 0.00037 and 0.3125 respectively. Inhibition data showed that the enzyme had least activity （71.70） when blanched at 95℃ for 7 mins with chemical treatment involving a combination of 0.5% Sodium metabisulphite （Food grade） and 0.5% Ascorbic acid （Food grade）. The activity was highest （83.02） when it was blanched at 95 ℃ for 7 rains. This study has shown that it is possible to inhibit polyphenol oxidase activity in white yam using the chemical pretreatments and processing conditions described in this study for possible adoption in the production of packaged frozen yam chips by food industries.
基金Supported by Undergraduate Innovation and Enterpreneurship Training Program(202110514002)Huanggang Normal University High-level Cultivation Project(202108504).
文摘[Objectives]This study was conducted to investigate the effects of embedding conditions on activity and catalytic properties of immobilized polyphenol oxidase.[Methods]Polyphenol oxidase was immobilized in a polymer material by the embedding method,and the optimal immobilization conditions were obtained by single factor tests:CaCl_(2) concentration 2.0%,sodium alginate concentration 2.0%,immobilization time 2 h and mass ratio of enzyme to carrier 10 mg/100 g,under which the immobilized enzyme activity was 93.33 U/g.Under the above conditions,the properties of polyphenol oxidase immobilized by sodium alginate(A-PPO)and free polyphenol oxidase were studied.[Results]The thermostability of A-PPO was better than that of the free enzyme,but the pH stability of A-PPO was inhibited.The Michaelis constant K_(m) values of free polyphenol oxidase and A-PPO were 0.37 and 0.48 mmol/L,respectively,and the maximum reaction rate V_(max) values were 0.38 and 0.51 mmol/(L·g),respectively.[Conclusions]This study provides a theoretical basis for the study of the properties of polyphenol oxidase.
基金financially supported by the National Key R&D Program Subproject of China(2017YFD0401203-01).
文摘The effects of radiofrequency(RF)heating on the activity,structure,and surface hydrophobicity of mushroom polyphenol oxidase(PPO)were examined and four kinetic models of inactivation(First-order model,Weibull model,Logistic model and Bi-phasic model)were fitted.The results demonstrated that RF heating could effectively inactivate PPO,logistic and Bi-phasic model attained the best fit.The circular dichroism(CD)and fluorescence spectroscopy spectra revealed that RF heating at 65℃ for 180 s caused changes in the secondary and tertiary structures of PPO,reducing the α-helix content from 38.5% to 30.3% and red-shifting the emission peak wavelength of the maximum fluorescence intensity from 318 nm to 321 nm.RF heating also caused a significant enhancement of the surface hydrophobicity of the PPO(P<0.05).The color test results showed that RF heating could inhibit the browning of mushrooms(P<0.05).Thus,RF heating is an effective technique for the inactivation of enzymes and further research should be performed on RF heating applications to inactivate enzymes in the food industry.
文摘Enzymatic browning,primarily driven by polyphenol oxidase(PPO),poses a significant challenge in maintaining food quality and consumer acceptance across various sectors.This review critically examines available data on corn silk(Stigma maydis),an agro-industrial byproduct rich in antioxidant flavonoids(such as luteolin,apigenin,and formononetin),phenolic acids,and active carbohydrates.The gathered evidence indicates that corn silk compounds could effectively reduce PPO activity in both plant-derived and bacterial systems,suggesting they can mitigate browning through mechanisms that include direct enzyme inhibition and structural modulation of PPO’s biophysical properties.In vitro studies further reveal that corn silk extracts enhance radical-scavenging activity and may offer antimicrobial benefits,thus contributing to improved food stability.Although promising applications range from fresh-cut produce treatments to incorporation into edible coatings and functional beverages,further research is required to optimize extraction methods,achieve formulation stability,and comprehensively assess sensory impacts and consumer acceptance.Overall,the reviewed research positions corn silk as a promising candidate for developing effective,safe,and environmentally friendly preservation strategies,while also highlighting the need for a multidisciplinary approach to fully integrate this natural resource into modern food systems.
基金funded by the National Natural Science Foundation of China[award 32102023]the Natural Science Foundation of Zhejiang Province,China[LQ22C200001]+1 种基金the Key Research and Development Program of Zhejiang Province,China[award 2023C02006]the Ningbo Agricultural Research Program of China[award 2022S143].
文摘Polyphenol oxidase(PPO)is the main enzyme initiating internal browning in peach fruit stored at low tem-perature.Previous studies showed fatty acids activated PPO,but its specific effect and mechanism of activation on PPO are still not clear.Thus,the effects of fatty acids on the biochemical properties and structural confor-mation of PPO were studied,with sodium dodecyl sulfate used as comparison.The highest degree of activation(5 folds)of membrane-bound PPO(mPPO)was found with 2.2 mM linoleic acid(LA)and its optimal activity was observed also around pH 7.0.Further structure analysis showed LA led to an increase ofα-helix content of mPPO from 23.53%to 52.33%;the maximum emission wavelength of treated mPPO shifted from 338 to 340 nm with the fluorescence intensity increased from 446 to 510.LA also can form hydrogen bonds and hydrophobic in-teractions with mPPO.These results indicated that LA could contribute to a more stable and open enzyme structure,thus activated mPPO.The results will provide more information for PPO activation that highly probably occurs in postharvest peach fruit and its relationship with internal browning.
基金supported by the National Natural Science Foundation of China[No.32460607,No.31960491]Gansu Provincial Natural Science Foundation[No.23JRRA798]+1 种基金Gansu Provincial Science and Technology Programme(25CXGA050)Longnan Municipal Key Science and Technology Project(2025ZD01).
文摘In this study,ergothioneine liposomes were prepared via the reverse evaporation method,and the preparation conditions were optimized by single-factor experiments and response surface methodology.The optimal prep-aration conditions were determined as follows:the pH of the aqueous phase was 7.1,the ratio of membrane materials(soy lecithin:cholesterol)was 3.5:1,and the ratio of lipids to the drug(soy lecithin:ergothioneine)was 28:1,with an encapsulation efficiency of 77.6%.The prepared liposomes were characterized by uniform particle size and good stability,while retaining the antioxidant activity of ergothioneine.Subsequently,polyphenol oxidase(PPO)was extracted and purified from Lanzhou lily.The inhibitory effect of ergothioneine(EGT)on the PPO activity in lily bulbs was investigated by means of fluorescence spectroscopy,circular dichroism spectros-copy and other techniques.Fluorescence results showed that ergothioneine quenched the endogenous fluores-cence of PPO from Lanzhou lily through a static quenching mechanism.The formed complex was mainly stabilized by hydrophobic interactions,and this process only induced local conformational changes of the enzyme protein.Finally,storage experiments demonstrated that chitosan-modified ergothioneine liposomes effectively delayed the browning of lily bulbs.This study not only elucidated the core mechanism underlying the inhibition of lily PPO by ergothioneine,but also successfully prepared highly efficient and stable ergothioneine liposomes.It provides a natural preservation solution for Lanzhou lily and other similar browning-prone fruits and vegetables,and also offers a theoretical reference for the development of natural browning inhibitors and the application of liposomes in the storage of fruits and vegetables.
基金supported by the National Natural Science Foundation of China(Grant Nos.32160349,22368006)Natural Science Foundation of Guangxi Zhuang Autonomous Region(Grant No.2024GXNSFAA999185)Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology(Grant No.2024Z002).
文摘Pinus elliottii oleoresin(PEO)is a renewable feedstock for producing rosin and turpentine,yet storage-induced enzymatic browning can markedly impair the color quality of PEO and downstream rosin products.Rosin-derived materials are used in food-related products,including beverage emulsions and food-contact pack-aging;therefore,maintaining color stability is important for both consumer acceptance and commercial value.In this study,enzymatic browning in wet-stored PEO was linked to the leaching of phenolics from impurity pine needles into the aqueous phase.Polyphenol oxidase(PPO)was extracted from Pinus elliottii needles and char-acterized.The enzyme showed maximal activity at pH 7.0 and 35℃ and retained more than 80%activity over pH 6.5-7.5.Thermal deactivation kinetics indicated that the enzyme is heat sensitive.The enzyme exhibited high affinity toward epicatechin(Km=5.93 mM).A PEO browning model based on epicatechin was established,and the Weibull model accurately described browning development,supporting enzymatic browning as a key contributor to color deterioration during storage.L-cysteine(L-Cys)was evaluated as an antibrowning agent and showed a mixed inhibition pattern in kinetic assays;fluorescence spectroscopy and molecular docking suggested that its interaction with the enzyme is mainly stabilized by hydrogen bonding and hydrophobic contacts.Overall,this work clarifies the biochemical origin of oleoresin discoloration and provides a mechanistic basis for miti-gating rosin darkening during storage.
基金supported by the National Natural Science Foundation of China(No.32260617)the Ningxia Natural Science Foundation(No.2024AAC03110).
文摘To address color deterioration and nutrient loss during goji berry drying,this study proposes an innovative process combining acidic electrolyzed water(AEW)pretreatment with pulsed vacuum drying(PVD).Through systematic evaluation of drying characteristics,color,total phenolic content(TPC),total flavonoid content(TFC),total carotenoid content(TCC),antioxidant activity,browning index(BI),lipid oxidation degree,and polyphenol oxidase(PPO)activity,combined with fitting the PPO thermal inactivation pattern using first-order kinetic models and logistic models,and utilizing scanning electron microscopy(SEM),intrinsic fluorescence spectros-copy,and Fourier transform infrared spectroscopy(FTIR)techniques,the mechanisms of color retention and enzyme inhibition were comprehensively elucidated at the microstructural and protein conformation levels.Results indicate that AEW pretreatment effectively disrupts the wax layer on goji berries,significantly enhancing drying rate.The AEW30s treatment group demonstrated optimal overall performance,better preserving TPC,TFC,and TCC while reducing the browning index by 30.42%and significantly inhibiting lipid oxidation.Kinetic fitting of PPO inactivation revealed the Logistic model exhibited the highest goodness-of-fit(R^(2)>0.96),pre-dicting the lowest residual PPO activity in the AEW30s group,reduced by 15.4%compared to the control.Structural analysis indicated that AEW irreversibly inactivated PPO by disrupting its spatial conformation,manifested as quenching of endogenous fluorescence and decreased fluorescence intensity of tryptophan resi-dues.This study revealed the color-preserving mechanism of AEW combined with pulse vacuum drying from multiple perspectives,providing a theoretical basis for developing high-quality,sustainable goji berry drying technologies.
基金the National Key Basic Research and Develop-ment (973) Program of China (No. G1999075607) and the Henan Natural Science Foundation (No. G0111010700)
文摘In this study, the kinetics of inhibition of polyphenol oxidase by L-cysteine has been investigated. The inhibition of tobacco polyphenol oxidase was studied using the progress-of-substrate-reaction method proposed by Tsou, following the substrate reaction during irreversible inhibition of the enzyme activity. Analysis of the inhibition kinetics shows that inhibition occurs by an irreversible and non-complexation reaction. The microscopic rate constants were determined for reaction of the inhibitor both with the free enzyme and with the enzyme-substrate complex. The results show that the presence of the substrate has a significant protective effect of the enzyme against inactivation by L-cysteine.
基金supported by National First-class Discipline Program of Food Science and Technology JUFSTR20180204“Collaborative innovation center of food safety and quality control in Jiangsu Province”.
文摘Yellowing even browning of radish commonly occurred during the traditional pickling.This research aimed to determine the reason of yellowing of pickled radish,and propose the method for yellowing inhibition.The activity of endogenous enzymes in radish were analyzed,and the relationship between the activity and the browning was investigated.Myrosinase and polyphenol oxidase(PPO)were found as main potential enzymes resulting in browning of radish.During traditional salting processing,the myrosinase activity decreased,particularly at a high speed in the first 14 days,while the PPO activity did not decrease observably.The a*and b*values of salted radish were significantly correlated with myrosinase and PPO activity.Acid treatment was observed to be effective for browning inhibition of radish during soaking and storage,and the low pH conditions contributed to the preservation of original green color of radish.Stronger acidification during the first 3 d played a much more important role in browning inhibition than following weaker acidification treatment for 27 d.Low pH showed an inhibition effect on PPO activity,but myrosinase reactivity was more sensitive to pH changes than PPO.The myrosinase in the radish treated in the pickling solution at pH 2 was completely inactivated during the first 3 days.Further investigation of pH effect on improvement of salted radish color concluded that pH 2.4 was the optimal pH for the inactivation of myrosinase and PPO.Accordingly,short-term accurate acidification coupled with traditional salting treatment was originally proposed for effective browning inhibition of pickled radish.
基金Supported by the Science and Technology Foundation of Fujian Province (No. 2004N002)the National Natural Science Foundation of China (No. 30570408)
文摘Polyphenol oxidase （PPO） is the enzyme responsible for enzymatic browning during the growth of insects. It is also involved in defense reactions and is related with immunities in insects. PPO a metalloenzyme oxidase, catalyzes the oxidation of o-diphenol to o-quinone. The present paper describes the effects of benzaldehyde and its p-substituted derivatives on the activity of PPO from the fifth instar of Pieris rapae L. PPO from the fifth instar of Pieris rapae L. was purified using ammonium sulfate fractionation and chromatography on Sephadex G-100. The enzyme kinetics was characterized using L-3,4-dihydroxyphenylalanine （L-DOPA） as substrate. The results show that benzaldehyde, phydroxybenzaldehyde, p-chlorobenzaldehyde, and p-cyanobenzaldehyde can inhibit the PPO activity for the oxidation of L-DOPA. The inhibitor concentration leading to 50% activity lost, IC50, was estimated to be 5.90, 5.62, 2.83, and 2.91 mmol/L for the four tested inhibitors, respectively. Kinetic analyses show that the inhibitory effects of these compounds are reversible. Benzaldehyde, phydroxybenzaldehyde, and p-chlorobenzaldehyde are noncompetitive inhibitors while p-cyanobenzaldehyde is a mixed-type inhibitor. The inhibition constants were determined for all four inhibitors. p-chlorobenzaldehyde and p-cyanobenzaldehyde were more potent inhibitors than the other compounds. These results provide a basis for developing PPO inhibition-based pesticides.
基金supported by the Open Research Fund of Jiangsu Key Laboratory for Biomass Energy and Material(JSBEM202009)the National Nature Science Foundation of China(32100439)+1 种基金the Science and Technology Foundation of Suzhou(SNG201909)the Foundation of Suzhou Academy of Agricultural Sciences(21010).
文摘The harvested loquat fruits are prone to browning,leading to a decline in fruit quality.Inhibiting activity of polyphenol oxidase(PPO)is an important way to prevent browning.In this study,we evaluated the inhibitory impact of oligomeric procyanidins(OPC)on hydroxylation of monophenol and oxidation of o-diphenol catalyzed by PPO and effect of OPC on loquat fruits storage.The obtained results revealed that OPC could attenuate the activity of monophenolase and diphenolase.For monophenolase activity,the inhibition rate was observed to be dose-dependent with an IC50 of 11.6±3.4μg/mL for the steady-state rate.For diphenolase activity,OPC inhibited PPO activity(IC50=15.75±2.1μg/mL)with a reversible and competitive mechanism and quenched fluorescence of PPO by forming OPC-PPO complex with one binding site in a static procedure.In addition,the data obtained from storage assays revealed that OPC could enhance the quality of harvested loquat fruits by attenuating the PPO activity,augmenting the content of total phenolics and flavonoids,and simultaneously delaying the browning of loquats.In this research,we identified a potent PPO inhibitor and expanded its potential as a food preservative.
文摘Polyphenolic compound in processing apple （Malus domestica Borkh.） varieties and the relationship between polyphenol content and enzymatic browning were studied to provide reference for raw material selection and processing method optimization. The content of polyphenol compound in 10 processing apple varieties （4 cider and 6 juice varieties） were analyzed using the Folin-Ciocalteu method and HPLC. The degree of browning and the activities of polyphenol oxidase were also studied. The content and proportion of the polyphenol varied depending on the variety. Bitter varieties globally showed a higher polyphenol concentration than sweet or acid varieties. Proanthocyanidins, chlorogenic acid, （＋）-catechin, （-）-epicatechin were high-concentrated polyphenols in apple fruits. Phloridzin, the unique polyphenol of apple, was abundant in the bitter variety Frequin rouge fruit. Total polyphenols, proanthocyanidins, （＋）-catechin, and phloridzin had higher correlations with browning. The correlation was low between chlorogenic acid and browning. The polyphenolic profiles were correlated with the apple types. Cider apples contained more polyphenol than juice apple varieties. The content of flavan-3-ol has a close relationship with fruit browning.
文摘Elevation affects the contents of polyphenols involved in the plants’resistance to the environment.In this study,polyphenolic contents,as well as the activity of polyphenol oxidase(PPO),were evaluated in mature cigar plants at different elevation levels.The results showed that:(1)The contents of chlorogenic acid,rutin,and scopolamine in cigar leaves increased gradually at all elevation levels,reaching a maximum 25 d after the mature stage.(2)With an increase in altitude,the polyphenolic compounds’contents increased,having the lowest values at 350 m height and the highest at 1090 m height.(3)As for the PPO activity in cigar leaves,the general trend showed an increase first followed by a decrease in activity during the mature period.(4)PPO activity in the leaves of cigar plants planted at 840 m height was substantially elevated compared to those growing at 600 m and 350 m height.Interestingly,the leaves planted at 1090 m height had the lowest PPO activity.(5)There were significant positive correlations between altitude and the contents of chlorogenic acid,rutin,and scopolamine within the plants leaves.Altitude negatively correlated the proportion of chlorogenic acid and scopolamine whereas positively correlated rutin proportion within the total polyphenols.Temperature had negative correlations with the contents of chlorogenic acid,rutin,and scopolamine,while sunlight intensity had positive correlations on their contents.Conversely,there were no significant correlations between altitude,temperature,and light intensity on PPO activity.Therefore,this study can provide valuable insight and a theoretical basis for the production of premium cigars.
基金supported by the Leverhulme Trust Research Project(Grant No.RPG-2020-021).
文摘Paper and pulp mills generate substantial volumes of wastewater containing lignin-derived compounds that are challenging to degrade using conventional wastewater treatment methods.This study presents a novel biofilm-based process for enhanced lignin removal in wastewater using the fungus Neurospora discreta,which effectively degrades lignin and forms robust biofilms at the air–liquid interface under specific conditions.The process was optimised using the Taguchi design of experiments approach,and three factors including pH,copper sulphate concentration,and trace element concentration were evaluated at three levels.Experimental data were analysed against three responses:lignin degradation efficiency and the activities of two ligninolytic enzymes(polyphenol oxidase and versatile peroxidase).The results indicated that wastewater pH was the most significant parameter affecting lignin degradation efficiency and enzyme activities.Over 70%lignin degradation was achieved at pH levels of 5 and 6 with copper sulphate concentrations above 4 mg/L,while degradation efficiency drastically dropped to 45%at a pH value of 7.Reversed-phase high-performance liquid chromatography analysis demonstrated the effects of the three factors on the polar and non-polar components of lignin in wastewater,revealing a clear decrease in all peak areas after treatment.Additionally,significant relationships were observed between biofilm properties(including porosity,water retention value,polysaccharide content,and protein content)and lignin removal efficiency.This study also reported for the first time the presence of versatile peroxidase,a ligninolytic enzyme,in Neurospora sp.
基金Supported by National Natural Science Foundation of China(30872008)the Special Fund for Basic Research of Central Universities(DL10BA04)~~
文摘[Objective] This study aimed to explore the effects of treatments with three types of exogenous oxidase solutions and H2O2.solution on the somatic embryogenesis of Fraxinus mandshurica Rupr. （Oleaceae）. [Method] The immature zygotic cotyledons were treated with PPQ （polyphenol oxidase） solution, GQD （glucose oxidase） solution, SOD （superoxide dismutase） solution and H202 （hydrogen peroxide） at different concentrations to explore the effects on the growth, browning and somatic embryogenesis on cotyledon explants in the somatic embryogenesis of F. mandshurica. Through comparative analysis on the effects of different treatments on somatic embryogenesis of F. mandshurica, the relationship between explants browning and somatic embryogenesis was uncovered during the somatic embryogenesis of F. mandshurica. [Result] H2O2 treatment not only advanced the explants browning, but also inhibited the growth and somatic embryogenesis of explants; different concentrations of PPQ promoted the growth and browning of explants, as well as improving the incidence of somatic embryogenesis; both GOD and SOD treatment could raise the explants browning rate; when somatic embryogenesis of explants treated with enzyme solutions advanced, the incidence of somatic embryogenesis was low; however, when the disparity of the incidence of somatic embryogenesis between 30 and 60 d treatments reached its peak, the incidence of somatic embryogenesis was also high. [Conclusion] The results of this study provide basis for raising the incidence and improving the status of somatic embryogenesis of F. mandshurica, as well as optimizing the somatic embryogenesis system of F. mandshurica.
