RESUMEN
Raman Optical Activity combined with Circularly Polarized Luminescence (ROA-CPL) was used in the spectral recognition of glutathione peptide (GSH) and its model post-translational modifications (PTMs). We demonstrate the potential of ROA spectroscopy and CPL probes (EuCl3, Na3[Eu(DPA)3], NaEuEDTA) in the study of unmodified peptide, i.e. GSH, and its derivatives, i.e. glutathione oxidized (GSSG), S-acetylglutathione (GSAc) and S-nitrosoglutathione (GSNO). ROA spectral features of GSH, GSSG, and GSAc were determined along with thier changes upon the different pH conditions. Apart from the ROA, induced CPL signals of Eu(III) probes also proved to be sensitive to the structural modifications of GSH-based model PTMs, enabling their spectral recognition, especially by the NaEuEDTA probe.
Asunto(s)
Glutatión , Espectrometría Raman , Glutatión/química , Luminiscencia , Mediciones Luminiscentes , Procesamiento Proteico-Postraduccional , Concentración de Iones de HidrógenoRESUMEN
Osteomyelitis is an osseous infectious disease that primarily affects children and the elderly with high morbidity and recurrence. The conventional treatments of osteomyelitis contain long-term and high-dose systemic antibiotics with debridements, which are not effective and lead to antibiotic resistance with serious side/adverse effects in many cases. Hence, developing novel antibiotic-free interventions against osteomyelitis (especially antibiotic-resistant bacterial infection) is urgent and anticipated. Here, a bone mesenchymal stem cell membrane-constructed nanocell (CFE@CM) was fabricated against osteomyelitis with the characteristics of acid-responsiveness, hydrogen peroxide self-supplying, enhanced chemodynamic therapeutic efficacy, bone marrow targeting and cuproptosis induction. Notably, mRNA sequencing was applied to unveil the underlying biological mechanisms and found that the biological processes related to copper ion binding, oxidative phosphorylation, peptide biosynthesis and metabolism, etc., were disturbed by CFE@CM in bacteria. This work provided an innovative antibiotic-free strategy against osteomyelitis through copper-enhanced Fenton reaction and distinct cuproptosis, promising to complement the current insufficient therapeutic regimen in clinic.
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Cobre , Osteomielitis , Osteomielitis/tratamiento farmacológico , Animales , Cobre/química , Cobre/farmacología , Concentración de Iones de Hidrógeno , Células Madre Mesenquimatosas/efectos de los fármacos , Células Madre Mesenquimatosas/citología , Ratones , Peróxido de Hidrógeno/metabolismo , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Antibacterianos/química , Humanos , Staphylococcus aureus/efectos de los fármacosRESUMEN
A newly developed 2H5MA-MOF sensor by covalently linking NH2-MIL-53(Al) with 2'-Hydroxy-5'-methylacetophenon, designed for highly sensitive and selective detection of Cd2+ ions using fluorometric methods. Detailed structural and morphological analyses confirmed the sensor's unique properties. It demonstrated an impressive linear detection range from 0 to 2 ppm, with an exceptionally low detection limit of 5.77 × 10-2 ppm and a quantification limit of 1.75 × 10-1 ppm, indicating its high sensitivity (R2 = 0.9996). The sensor also responded quickly, detecting Cd2+ within just 30 s at pH 4. We successfully tested it on real samples of tap water and human blood plasma, achieving recovery rates between 96 % and 104 %. The accuracy of these findings was further validated by comparison with ICP-OES. Overall, the 2H5MA-MOF sensor shows great potential for fast, ultra-sensitive, and reliable detection of Cd2+ ions, making it a promising tool for environmental and biomedical applications.
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Cadmio , Agua Potable , Límite de Detección , Estructuras Metalorgánicas , Cadmio/sangre , Cadmio/análisis , Humanos , Estructuras Metalorgánicas/química , Agua Potable/análisis , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/sangre , Iones/sangre , Concentración de Iones de HidrógenoRESUMEN
Cryptococcus gattii and its medical implications have been extensively studied. There is, however, a significant knowledge gap regarding cryptococcal survival in its environmental niche, namely woody material, which is glaring given that infection is linked to environmental populations. A gene from C. gattii (WM276), the predominant global molecular type (VGI), has been sequenced and annotated as a putative cellulase. It is therefore, of both medical and industrial intertest to delineate the structure and function of this enzyme. A homology model of the enzyme was constructed as a fusion protein to a maltose binding protein (MBP). The CGB_E4160W gene was overexpressed as an MBP fusion enzyme in Escherichia coli T7 cells and purified to homogeneity using amylose affinity chromatography. The structural and functional character of the enzyme was investigated using fluorescence spectroscopy and enzyme activity assays, respectively. The optimal enzyme pH and temperature were found to be 6.0 and 50 °C, respectively, with an optimal salt concentration of 500 mM. Secondary structure analysis using Far-UV CD reveals that the MBP fusion protein is primarily α-helical with some ß-sheets. Intrinsic tryptophan fluorescence illustrates that the MBP-cellulase undergoes a conformational change in the presence of its substrate, CMC-Na+. The thermotolerant and halotolerant nature of this particular cellulase, makes it useful for industrial applications, and adds to our understanding of the pathogen's environmental physiology.
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Celulasa , Cryptococcus gattii , Escherichia coli , Cryptococcus gattii/genética , Cryptococcus gattii/enzimología , Cryptococcus gattii/química , Celulasa/genética , Celulasa/química , Celulasa/aislamiento & purificación , Celulasa/metabolismo , Celulasa/biosíntesis , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/aislamiento & purificación , Proteínas Recombinantes de Fusión/metabolismo , Proteínas Recombinantes de Fusión/biosíntesis , Proteínas Fúngicas/genética , Proteínas Fúngicas/química , Proteínas Fúngicas/aislamiento & purificación , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/biosíntesis , Expresión Génica , Clonación Molecular , Proteínas de Unión a Maltosa/genética , Proteínas de Unión a Maltosa/química , Proteínas de Unión a Maltosa/metabolismo , Concentración de Iones de Hidrógeno , TemperaturaRESUMEN
Shewanella baltica is a specific spoilage organism of golden pomfret. This study aims to explore the antibacterial mechanism of slightly acidic electrolysed water (SAEW) against S. baltica (strains ABa4, ABe2 and BBe1) in golden pomfret broths by metabolomics, proteomics and bioinformatics analyses. S. baltica was decreased by at least 3.94 log CFU/mL after SAEW treatment, and strain ABa4 had the highest resistance. Under SAEW stress, amino acids and organic acids in S. baltica decreased, and nucleotide related compounds degraded. Furthermore, 100 differentially expressed proteins (DEPs) were identified. Most DEPs of strains ABe2 and BBe1 were down-regulated, while some DEPs of strain ABa4 were up-regulated, especially those oxidative stress related proteins. These results suggest that the modes of SAEW against S. baltica can be traced to the inhibition of amino acid, carbon, nucleotide and sulphur metabolisms, and the loss of functional proteins for temperature regulation, translation, motility and protein folding.
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Proteínas Bacterianas , Shewanella , Shewanella/metabolismo , Shewanella/química , Shewanella/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Agua/metabolismo , Agua/química , Electrólisis , Antibacterianos/farmacología , Antibacterianos/metabolismo , Antibacterianos/química , Concentración de Iones de Hidrógeno , Vigna/química , Vigna/microbiología , Vigna/metabolismoRESUMEN
The objective of this study was to develop and validate a novel microfluidic paper-based analytical device (µPADpH) for determining the pH levels in foods. Anthocyanins from red cabbage aqueous extract (RCAE) were used as its analytical sensor. Whatman No. 1 filter paper was the most suitable for the device due to its porosity and fiber organization, which allows for maximum color intensity and minimal color heterogeneity of the RCAE in the detection zone of the µPADpH. To ensure the color stability of the RCAE for commercial use of the µPADpH, gum arabic was added. The geometric design of the µPADpH, including the channel length and separation zone diameter, was systematically optimized using colored food. The validation showed that the µPADpH did not differ from the pH meter when analyzing natural foods. However, certain additives in processed foods were found to increase the pH values.
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Antocianinas , Brassica , Goma Arábiga , Antocianinas/química , Antocianinas/análisis , Brassica/química , Concentración de Iones de Hidrógeno , Goma Arábiga/química , Papel , Técnicas Analíticas Microfluídicas/instrumentaciónRESUMEN
With the aim of expanding the potential application scope of mulberries, eleven pH-switchable deep eutectic solvents were screened for the ultrasonic-assisted extraction of mulberry polysaccharides, and a salt/salt aqueous two-phase system was constructed for the efficient separation of mulberry polysaccharides by regulating the system pH. DES-9 (tetraethylammonium chloride: octanoic acid molar ratio = 1: 2) with a critical response pH value of approximately 6.1 was concluded to be the best extraction solvent for extracting mulberry polysaccharides. A maximum polysaccharide extraction yield of 270.71 mg/g was obtained under the optimal conditions. The maximum polysaccharide extraction efficiency was 78.09 % for the pH-driven tetraethylammonium chloride/K2HPO4 aqueous two-phase system. An acidic ß-pyran mulberry polysaccharide with a low-molecular weight of 9.26 kDa and a confirmed monosaccharide composition were obtained. This efficient and environmentally friendly polysaccharide separation method offers a new approach for the efficient extraction and utilization of other plant polysaccharides.
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Disolventes Eutécticos Profundos , Morus , Extractos Vegetales , Polisacáridos , Morus/química , Polisacáridos/química , Polisacáridos/aislamiento & purificación , Concentración de Iones de Hidrógeno , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Disolventes Eutécticos Profundos/química , Fraccionamiento Químico/métodos , Peso Molecular , Frutas/química , Cloruro de Sodio/químicaRESUMEN
A trypsin affinity material was prepared by covalently immobilizing buckwheat trypsin inhibitor (BTI) on epichlorohydrin-activated cross-linked agarose gel (Selfinose CL 6 B). The optimal conditions for activating Selfinose CL 6 B were 15 % epichlorohydrin and 0.8 M NaOH at 40 °C for 2 h. The optimal pH for immobilizing BTI was 9.5. BTI-Sefinose CL 6 B showed a maximum adsorption capacity of 2.25 mg trypsin/(g support). The material also displayed good reusability, retaining over 90 % of its initial adsorption capacity after 30 cycles. High-purity trypsin was obtained from locust homogenate using BTI-Selfinose CL 6 B through one-step affinity chromatography. The molecular mass and Km value of locust trypsin were determined as 27 kDa and 0.241 mM using N-benzoyl-DL-arginine-nitroanilide as substrate. The optimal temperature and pH of trypsin activity were 55 °C and 9.0, respectively. The enzyme exhibited good stability in the temperature range of 30-50 °C and pH range of 4.0-10.0. BTI-Selfinose CL 6 B demonstrates potential application in the preparation of high-purity trypsin and the discovery of more novel trypsin from various species.
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Cromatografía de Afinidad , Proteínas Recombinantes , Inhibidores de Tripsina , Tripsina , Tripsina/química , Tripsina/metabolismo , Inhibidores de Tripsina/química , Inhibidores de Tripsina/aislamiento & purificación , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , Cromatografía de Afinidad/métodos , Proteínas de Plantas/aislamiento & purificación , Proteínas de Plantas/química , Concentración de Iones de Hidrógeno , Fagopyrum/química , Temperatura , Sefarosa/química , Estabilidad de EnzimasRESUMEN
The development of biosensing electronics for real-time sweat analysis has attracted increasing research interest due to their promising applications for non-invasive health monitoring. However, one of the critical challenges lies in the sebum interference that largely limits the sensing reliability in practical scenarios. Herein, we report a flexible epidermal secretion-purified biosensing patch with a hydrogel filtering membrane that can effectively eliminate the impact of sebum and sebum-soluble substances. The as-prepared sebum filtering membranes feature a dual-layer sebum-resistant structure based on the poly(hydroxyethyl methacrylate) hydrogel functionalized with nano-brush structured poly(sulfobetaine) to eliminate interferences and provide self-cleaning capability. Furthermore, the unidirectional flow microfluidic channels design based on the Tesla valve was incorporated into the biosensing patch to prevent external sebum contamination and allow effective sweat refreshing for reliable sensing. By seamlessly combining these components, the epidermal secretion-purified biosensing patch enables continuous monitoring of sweat uric acid, pH, and sodium ions with significantly improved accuracy of up to 12 %. The proposed strategy for enhanced sweat sensing reliability without sebum interference shows desirable compatibility for different types of biosensors and would inspire the advances of flexible and wearable devices for non-invasive healthcare.
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Técnicas Biosensibles , Hidrogeles , Sebo , Sudor , Técnicas Biosensibles/métodos , Técnicas Biosensibles/instrumentación , Humanos , Sebo/metabolismo , Hidrogeles/química , Sudor/química , Epidermis/metabolismo , Dispositivos Electrónicos Vestibles , Microfluídica/métodos , Ácido Úrico/análisis , Membranas Artificiales , Concentración de Iones de HidrógenoRESUMEN
The acidity of atmospheric aerosols influences fundamental physicochemical processes that affect climate and human health. We recently developed a novel and facile water-probe-based method for directly measuring of the pH for micrometer-size droplets, providing a promising technique to better understand aerosol acidity in the atmosphere. The complex chemical composition of fine particles in the ambient air, however, poses certain challenges to using a water-probe for pH measurement, including interference from interactions between compositions and the influence of similar compositions on water structure. To explore the universality of our method, it was employed to measure the pH of ammonium, nitrate, carbonate, sulfate, and chloride particles. The pH of particles covering a broad range (0-14) were accurately determined, thereby demonstrating that our method can be generally applied, even to alkaline particles. Furthermore, a standard spectral library was developed by integrating the standard spectra of common hydrated ions extracted through the water-probe. The library can be employed to identify particle composition and overcome the spectral overlap problem resulting from similar effects. Using the spectral library, all ions were identified and their concentrations were determined, in turn allowing successful pH measurement of multicomponent (ammonium-sulfate-nitrate-chloride) particles. Insights into the synergistic effect of Cl-, NO3-, and NH4+ depletion obtained with our approach revealed the interplay between pH and volatile partitioning. Given the ubiquity of component partitioning and pH variation in particles, the water probe may provide a new perspective on the underlying mechanisms of aerosol aging and aerosol-cloud interaction.
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Aerosoles , Monitoreo del Ambiente , Espectrometría Raman , Agua , Concentración de Iones de Hidrógeno , Espectrometría Raman/métodos , Agua/química , Monitoreo del Ambiente/métodos , Aerosoles/análisis , Contaminantes Atmosféricos/análisis , Contaminantes Atmosféricos/química , Atmósfera/química , Material Particulado/análisisRESUMEN
During the water treatment process, chlorination and ultraviolet (UV) sterilization can modify microplastics (MPs) and alter their physicochemical properties, causing various changes between MPs and other pollutants. In this study, the impact of chlorination and UV modification on the physicochemical properties of polystyrene (PS) and polyvinyl chloride (PVC) were investigated, and the adsorption behavior of pefloxacin (PEF) before and after modification was examined. The effect of pH, ionic strength, dissolved organic matter, heavy metal ions and other water environmental conditions on adsorption behavior was revealed. The results showed that PS had a higher adsorption capacity of PEF than PVC, and the modification increased the presence of O-containing functional groups in the MPs, thereby enhancing the adsorption capacity of both materials. Chlorination had a more significant impact on the physicochemical properties of MPs compared to UV irradiation within the same time period, leading to better adsorption performance of chlorination. The optimal pH for adsorption was found to be 6, and NaCl, sodium alginate and Cu2+ would inhibit adsorption to varying degrees, among which the inhibition caused by pH was the strongest. Chlorination and UV modification would weaken the inhibitory effect of environmental factors on the adsorption of PEF by MPs. The main mechanisms of adsorption involved electrostatic interaction and hydrogen bonding. The study clarified the effects of modification on the physicochemical properties of MPs, providing reference for subsequent biotoxicity analysis and environmental protection studies.
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Halogenación , Pefloxacina , Poliestirenos , Cloruro de Polivinilo , Rayos Ultravioleta , Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Cloruro de Polivinilo/química , Contaminantes Químicos del Agua/química , Poliestirenos/química , Purificación del Agua/métodos , Pefloxacina/química , Concentración de Iones de HidrógenoRESUMEN
High ammonia-nitrogen digestate has become a key bottleneck limiting the anaerobic digestion of organic solid waste. Vacuum ammonia stripping can simultaneously remove and recover ammonia nitrogen, which has attracted a lot of attention in recent years. To investigate the parameter effects on the efficiency and mass transfer, five combination conditions (53 °C 15 kPa, 60 °C 20 kPa, 65 °C 25 kPa, 72 °C 35 kPa, and 81 °C 50 kPa) were conducted for ammonia stripping of sludge digestate. The results showed that 80% of ammonia nitrogen was stripped in 45 min for all experimental groups, but the ammonia transfer coefficient varied under different conditions, which increased with the rising of boiling point temperature, and reached the maximum value (39.0 mm/hr) at 81 °C 50 kPa. The ammonia nitrogen removal efficiency was more than 80% for 30 min vacuum stripping after adjusting the initial pH to above 9.5, and adjustment of the initial alkalinity also affects the pH value of liquid digestate. It was found that pH and alkalinity are the key factors influencing the ammonia nitrogen dissociation and removal efficiency, while temperature and vacuum mainly affect the ammonia nitrogen mass transfer and removal velocity. In terms of the mechanism of vacuum ammonia stripping, it underwent alkalinity destruction, pH enhancement, ammonia nitrogen dissociation, and free ammonia removal. In this study, two-stage experiments of alkalinity destruction and ammonia removal were also carried out, which showed that the two-stage configuration was beneficial for ammonia removal. It provides a theoretical basis and practical technology for the vacuum ammonia stripping from liquid digestate of organic solid waste.
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Amoníaco , Temperatura , Eliminación de Residuos Líquidos , Amoníaco/química , Concentración de Iones de Hidrógeno , Vacio , Eliminación de Residuos Líquidos/métodos , Nitrógeno , Aguas del Alcantarillado/química , PresiónRESUMEN
Naphthenic acids, NAs, are a major contaminant of concern and a focus of much research around remediation of oil sand process affected waters, OSPW. Using activated carbon adsorbents are an attractive option given their low cost of fabrication and implementation. A deeper evaluation of the effect NA structural differences have on uptake affinity is warranted. Here we provide an in-depth exploration of NA adsorption including many more model NA species than have been assessed previously with evaluation of adsorption kinetics and isotherms at the relevant alkaline pH of OSPW using several different carbon adsorbents with pH buffering to simulate the behaviour of real OSPW. Uptake for the NA varied considerably regardless of the activated carbon used, ranging from 350 mg/g to near zero highlighting recalcitrant NAs. The equilibrium data was explored to identify structural features of these species and key physiochemical properties that influence adsorption. We found that certain NA will be resistant to adsorption when hydrophobic adsorbents are used. Adsorption isotherm modelling helped explore interactions occurring at the interface between NA and adsorbent surfaces. We identified the importance of NA hydrophobicity for activated carbon uptake. Evidence is also presented that indicates favorable hydrogen bonding between certain NA and surface site hydroxyl groups, demonstrating the importance of adsorbent surface functionality for NA uptake. This research highlights the challenges associated with removing NAs from OSPW through adsorption and also identifies how adsorbent surface chemistry modification can be used to increase the removal efficiency of recalcitrant NA species.
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Ácidos Carboxílicos , Contaminantes Químicos del Agua , Adsorción , Ácidos Carboxílicos/química , Contaminantes Químicos del Agua/química , Carbón Orgánico/química , Modelos Químicos , Cinética , Concentración de Iones de HidrógenoRESUMEN
Thermodynamic modeling is still the most widely used method to characterize aerosol acidity, a critical physicochemical property of atmospheric aerosols. However, it remains unclear whether gas-aerosol partitioning should be incorporated when thermodynamic models are employed to estimate the acidity of coarse particles. In this work, field measurements were conducted at a coastal city in northern China across three seasons, and covered wide ranges of temperature, relative humidity and NH3 concentrations. We examined the performance of different modes of ISORROPIA-II (a widely used aerosol thermodynamic model) in estimating aerosol acidity of coarse and fine particles. The M0 mode, which incorporates gas-phase data and runs the model in the forward mode, provided reasonable estimation of aerosol acidity for coarse and fine particles. Compared to M0, the M1 mode, which runs the model in the forward mode but does not include gas-phase data, may capture the general trend of aerosol acidity but underestimates pH for both coarse and fine particles; M2, which runs the model in the reverse mode, results in large errors in estimated aerosol pH for both coarse and fine particles and should not be used for aerosol acidity calculations. However, M1 significantly underestimates liquid water contents for both fine and coarse particles, while M2 provides reliable estimation of liquid water contents. In summary, our work highlights the importance of incorporating gas-aerosol partitioning when estimating coarse particle acidity, and thus may help improve our understanding of acidity of coarse particles.
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Aerosoles , Contaminantes Atmosféricos , Modelos Químicos , Termodinámica , Aerosoles/análisis , Aerosoles/química , Contaminantes Atmosféricos/química , Contaminantes Atmosféricos/análisis , China , Monitoreo del Ambiente/métodos , Material Particulado/química , Material Particulado/análisis , Concentración de Iones de Hidrógeno , Tamaño de la PartículaRESUMEN
The anaerobic acid production experiments were conducted with the pretreated kitchen waste under pH adjustment. The results showed that pH 8 was considered to be the most suitable condition for acid production, especially for the formation of acetic acid and propionic acid. The average value of total volatile fatty acid at pH 8 was 8814 mg COD/L, 1.5 times of that under blank condition. The average yield of acetic acid and propionic acid was 3302 mg COD/L and 2891 mg COD/L, respectively. The activities of key functional enzymes such as phosphotransacetylase, acetokinase, oxaloacetate transcarboxylase and succinyl-coA transferase were all enhanced. To further explore the regulatory mechanisms within the system, the distribution of microorganisms at different levels in the fermentation system was obtained by microbial sequencing, results indicating that the relative abundances of Clostridiales, Bacteroidales, Chloroflexi, Clostridium, Bacteroidetes and Propionibacteriales, which were great contributors for the hydrolysis and acidification, increased rapidly at pH 8 compared with the blank group. Besides, the proportion of genes encoding key enzymes was generally increased, which further verified the mechanism of hydrolytic acidification and acetic acid production of organic matter under pH regulation.
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Ácidos Grasos Volátiles , Concentración de Iones de Hidrógeno , Ácidos Grasos Volátiles/metabolismo , Fermentación , Ácido Acético/metabolismo , Reactores BiológicosRESUMEN
The spoilage of irradiated ready-to-eat chicken feet (RTECF) seriously affects the food's quality, resulting in package swelling and off-flavors, both of which are highly undesirable to stakeholders and consumers. To investigate the spoilage characteristics of irradiated RTECF and the microorganisms responsible for the spoilage and swelling, the changes in physicochemical properties, microbial community, and volatile organic compounds (VOCs) between normal and spoiled RTECF were evaluated. Compared with normal samples, the spoiled RTECF showed a higher pH value and total volatile basic nitrogen (TVB-N) value, lower color value, and texture features (P < 0.05). Acinetobacter, Pseudomonas, Lactobacillus, and Candida were the dominant genera responsible for RTECF spoilage as confirmed through both culture-dependent methods and high-throughput sequencing (HTS). The results of the verification for gas-producing strains showed that Lactobacillus brevis could cause RTECF packaging to swell. A total of 20 key VOCs were identified using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results of Pearson correlation analysis (|r|>0.8, P < 0.05) showed that 12 dominant core microbial genera had a significant effect on the flavor of RTECF before and after spoilage. This study provides a theoretical reference for solving the problem of RTECF spoilage and improving the overall quality of RTECF products.
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Bacterias , Pollos , Irradiación de Alimentos , Microbiología de Alimentos , Compuestos Orgánicos Volátiles , Pollos/microbiología , Animales , Compuestos Orgánicos Volátiles/análisis , Compuestos Orgánicos Volátiles/química , Compuestos Orgánicos Volátiles/metabolismo , Bacterias/clasificación , Bacterias/efectos de la radiación , Bacterias/aislamiento & purificación , Bacterias/genética , Bacterias/crecimiento & desarrollo , Bacterias/metabolismo , Irradiación de Alimentos/métodos , Microbiota/efectos de la radiación , Embalaje de Alimentos/métodos , Cromatografía de Gases y Espectrometría de Masas , Concentración de Iones de Hidrógeno , Comida Rápida/microbiología , Comida Rápida/análisisRESUMEN
This study aimed to assess the impact of adaptation of ten strains of O157:H7 and non-O157 Escherichia coli to low pH (acid shock or slow acidification) and the effects of this exposure or not on the resistance of E. coli strains to UV radiation in orange juice (pH 3.5). The acid-shocked cells were obtained through culture in tryptic soy broth (TSB) with a final pH of 4.8, which was adjusted by hydrochloric, lactic, or citric acid and subsequently inoculated in orange juice at 4 °C for 30 days. No significant differences (p > 0.05) in survival in orange juice were observed between the serotypes O157:H7 and non-O157:H7 for acid-shocked experiments. After slow acidification, where the cells were cultured in TSB supplemented with glucose 1% (TSB + G), a significant increase (p < 0.05) in survival was observed for all strains evaluated. The D-values (radiation dose (J/cm2) necessary to decrease the microbial population by 90%) were determined as the inverse of the slopes of the regressions (k) obtained by plotting log (N/N0). The results show that among the strains tested, E. coli O157:H7 (303/00) and O26:H11 were the most resistant and sensitive strains, respectively. According to our results, the method of acid adaptation contributes to increasing the UV resistance for most of the strains tested.
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Adaptación Fisiológica , Citrus sinensis , Escherichia coli O157 , Jugos de Frutas y Vegetales , Rayos Ultravioleta , Escherichia coli O157/efectos de la radiación , Escherichia coli O157/crecimiento & desarrollo , Escherichia coli O157/efectos de los fármacos , Jugos de Frutas y Vegetales/microbiología , Jugos de Frutas y Vegetales/análisis , Citrus sinensis/microbiología , Citrus sinensis/química , Concentración de Iones de Hidrógeno , Escherichia coli/efectos de la radiación , Escherichia coli/efectos de los fármacos , Ácidos/farmacología , Recuento de Colonia Microbiana , Microbiología de Alimentos , Viabilidad Microbiana/efectos de la radiación , Viabilidad Microbiana/efectos de los fármacos , Irradiación de AlimentosRESUMEN
Essential amino acid, tryptophan which intake from food plays a critical role in numerous metabolic functions, exhibiting extensive biological functions and applications. Tryptophan is beneficial for the food sector by enhancing nutritional content and promoting the development of functional foods. A putative gene encoding tryptophan synthase was the first identified in Sphingobacterium soilsilvae Em02, a cellulosic bacterium making it inherently more environmentally friendly. The gene was cloned and expressed in exogenous host Escherichia coli, to elucidate its function. The recombinant tryptophan synthase with a molecular weight 42 KDa was expressed in soluble component. The enzymatic activity to tryptophan synthase in vivo was assessed using indole and L-serine and purified tryptophan synthase. The optimum enzymatic activity for tryptophan synthase was recorded at 50 ºC and pH 7.0, which was improved in the presence of metal ions Mg2+, Sr2+ and Mn2+, whereas Cu2+, Zn2+ and Co2+ proved to be inhibitory. Using site-directed mutagenesis, the consensus pattern HK-S-[GGGSN]-E-S in the tryptophan synthase was demonstrated with K100Q, S202A, G246A, E361A and S385A as the active sites. Tryptophan synthase has been demonstrated to possess the defining characteristics of the ß-subunits. The tryptophan synthase may eventually be useful for tryptophan production on a larger scale. Its diverse applications highlight the potential for improving both the quality and health benefits of food products, making it an essential component in advancing food science and technology.
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Escherichia coli , Mutagénesis Sitio-Dirigida , Triptófano Sintasa , Triptófano , Triptófano Sintasa/metabolismo , Triptófano Sintasa/genética , Triptófano Sintasa/química , Triptófano/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/química , Sphingomonadaceae/enzimología , Sphingomonadaceae/genética , Sphingomonadaceae/metabolismo , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/química , Dominio Catalítico , Clonación Molecular , Concentración de Iones de Hidrógeno , Indoles/metabolismo , Catálisis , Serina/metabolismoRESUMEN
Concerns about food safety and environmental impact from chemical surfactants have prompted interest in natural lignocellulosic materials as alternatives. In this study, we combined hydrated deep eutectic solvent (DES) pretreatment with ultrasound treatment to prepare lignocellulosic nanofibrils (LCNF) from bamboo shoot shells with appropriate surface properties for stabilizing Pickering emulsions. The pretreatment intensity effectively modulated the surface characteristics of LCNF, achieving desirable wettability through lignin retention and in-situ esterification. The resulting LCNF/curcumin Pickering emulsion (CPE) demonstrated curcumin protection and pH-responsive color changes, while the ensuing CPE/PVA composite film exhibited ultraviolet shielding, mechanical strength, oxygen barrier, and antioxidant properties. Furthermore, the CPE/PVA film showed promise as a real-time indicator for monitoring shrimp freshness, maintaining sensitivity to spoilage even after six months of storage. These findings advance the advancement of green LCNF technologies, providing eco-friendly solutions for valorizing bamboo shoot shells and enhancing the application of LCNF in Pickering emulsions.
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Curcumina , Emulsiones , Lignina , Nanofibras , Curcumina/química , Lignina/química , Emulsiones/química , Animales , Nanofibras/química , Antioxidantes/química , Disolventes Eutécticos Profundos/química , Brotes de la Planta/química , Sasa/química , Humectabilidad , Concentración de Iones de HidrógenoRESUMEN
Licorice is not only a widely used food, but also a classic tonic Chinese medicine, which mainly contains glycyrrhiza polysaccharides (GP) and flavonoids with excellent anti-inflammatory and antioxidant pharmacological activities. In this study, a neutral homogeneous polysaccharide (GP1-2) was isolated from Glycyrrhiza uralensis Fisch. However, its gelation behavior and properties have yet to be comprehensively studied. In this study, a Ca2+ cross-linked physical hydrogel based on neutral GP1-2 (GP1-2-Ca2+) is fabricated. The ability of metal ions to cross-linked gelation with GP1-2 is explored with respect to the polysaccharide concentrations, ion species, and pH environments. The pH range of Ca2+ cross-linked with GP1-2 to form hydrogel is 8 to 10, and the gelation concentration ranges from 20.0 % to 50.0 % w/v. Subsequently, the properties of the GP1-2-Ca2+ hydrogels are investigated using rheological measurements, scanning electron microscopy, free radical scavenging, MTT assays, healing capability, and enzyme-linked immunosorbent assays. The results reveal that the structure of GP1-2 presents an irregular porous structure, however, the physical gel formed after cross-linking with Ca2+ microscopically showed a globular porous structure with uniform distribution, suggesting that this structure characteristic may be used as a carrier material for drug delivery. Meanwhile, the GP1-2-Ca2+ hydrogel also possessed extraordinary viscoelasticity, cytocompatibility, antioxidant properties, anti-inflammatory activity, and ability to promote wound healing. Furthermore, the potential of GP1-2-Ca2+ hydrogels as drug delivery materials was validated by using rhein as a model drug for encapsulation, it is demonstrated that its cumulative release behavior of GP1-2-Ca2+ is pH-dependent. All in all, this study reveals the potential application of natural polysaccharides in drug delivery, highlighting its dual roles as carrier materials and bioactive ingredients.