Gluconate Research Articles

Development of an enzymatic cascade to systematically utilize lignocellulosic monosaccharide.

The fermentation valorization of two main lignocellulosic monosaccharides, glucose and xylose, is extensively developed; however, it is restricted by limited yield and process complexity. An in vitro enzymatic cascade reaction can be an alternative approach. In this study, a three-stage, five-enzyme cascade was developed to convert pretreated biomass to valuable chemicals. First, a ribose-5-phosphate isomerase B mutant isomerized xylose to d-xylulose with high substrate specificity, and a d-arabinose dehydrogenase continued to reduce d-xylulose to d-arabitol. Simultaneously, glucose was utilized for the coenzyme regeneration catalyzed by a glucose dehydrogenase, generating useful gluconic acid and achieving 73% of total conversion rate after 36 h. Then, six kinds of pretreated biomass lignocellulose were hydrolyzed by cellulase and hemicellulase, and corn cob was identified as the initial substrate for providing the highest monosaccharide content. A 65% conversion rate of the lignocellulosic xylose was obtained after 24 h. This study presents a proof of concept to convert main lignocellulosic monosaccharides systematically by an enzymatic cascade at stoichiometric ratio. © 2022 Society of Chemical Industry.

Significant alterations of intestinal symbiotic microbiota induced by intraperitoneal vaccination mediate changes in intestinal metabolism of NEW Genetically Improved Farmed Tilapia (NEW GIFT, Oreochromis niloticus)

BackgroundAfter millions of years of coevolution, symbiotic microbiota has become an integral part of the host and plays an important role in host immunity, metabolism, and health. Vaccination, as an effective means of preventing infectious diseases, has been playing a vital role in the prevention and control of human and animal diseases for decades. However, so far, minimal is known about the effect of vaccination on fish symbiotic microbiota, especially mucosal microbiota, and its correlation with intestinal metabolism remains unclear.MethodsHere we reported the effect of an inactivated bivalent Aeromonas hydrophila/Aeromonas veronii vaccine on the symbiotic microbiota and its correlation with the intestinal metabolism of farmed adult Nile tilapia (Oreochromis niloticus) by 16S rRNA gene high-throughput sequencing and gas chromatography-mass spectrometry metabolomics.ResultsResults showed that vaccination significantly changed the structure, composition, and predictive function of intestinal mucosal microbiota but did not significantly affect the symbiotic microbiota of other sites including gill mucosae, stomach contents, and stomach mucosae. Moreover, vaccination significantly reduced the relative abundance values of potential opportunistic pathogens such as Aeromonas, Escherichia–Shigella, and Acinetobacter in intestinal mucosae. Combined with the enhancement of immune function after vaccination, inactivated bivalent Aeromonas vaccination had a protective effect against the intestinal pathogen infection of tilapia. In addition, the metabolite differential analysis showed that vaccination significantly increased the concentrations of carbohydrate-related metabolites such as lactic acid, succinic acid, and gluconic acid but significantly decreased the concentrations of multiple lipid-related metabolites in tilapia intestines. Vaccination affected the intestinal metabolism of tilapia, which was further verified by the predictive function of intestinal microbiota. Furthermore, the correlation analyses showed that most of the intestinal differential microorganisms were significantly correlated with intestinal differential metabolites after vaccination, confirming that the effect of vaccination on intestinal metabolism was closely related to the intestinal microbiota.ConclusionsIn conclusion, this paper revealed the microbial and metabolic responses induced by inactivated vaccination, suggesting that intestinal microbiota might mediate the effect of vaccination on the intestinal metabolism of tilapia. It expanded the novel understanding of vaccine protective mechanisms from microbial and metabolic perspectives, providing important implications for the potential influence of vaccination on human intestinal microbiota and metabolism.-tufGxbkxhm-UiFTxxYHNiVideo

Study on the technology of brewing red raspberry wine by using new immobilized yeast technology

The aim of the present study was to establish a new process for brewing red raspberry wine with immobilized yeast and improve the value of red raspberry. Using the spore filaments of P. chrysogenum as a carrier to co-culture with yeast to obtain immobilized yeast. And the preparation method of immobilized yeast was optimized by single-factor experiment and orthogonal experiments. And the red raspberry wine was brewed in these conditions. The result shows that the optimal preparation conditions for the immobilized yeast of P. chrysogenum were 5g/L gluconic acid, 5g/L yeast extract, and the addition amount of P. chrysogenum spores 1 × 105cfu/ml. Compared with free yeast, the immobilized yeast of P. chrysogenum has better fermenting ability, can better keep the anthocyanins and polyphenols and other active ingredients of red raspberry. The quality of the wine was improved due to increase in aroma components such as alcohols and esters. The immobilized yeast of P. chrysogenum maintained good fermentation performance after three consecutive fermentations.

Glucose and pH responsive fluorescence detection system based on simple synthesis of silicon-coated perovskite quantum dots

Perovskite quantum dots (PQDs) are extremely unstable in ambient air due to their inherent structural instability, which limits the wide application of PQDs. In this work, silicon-coated CsPbBr3 PQDs (CsPbBr3@SiO2) was synthesized via a simple method. The SiO2 coating effectively isolated PQDs from water and oxygen in the environment, which were the main elements that destroyed the structure stability of PQDs. The synthesized CsPbBr3@SiO2 can be stored in water for more than 2 months and posessed wonderful dispersibility in aqueous solution. The fluorescence intensity remained unchanged within 7 days and only decreased by 11.9 % within 2 months. We found that CsPbBr3@SiO2 was extremely sensitive to environmental pH, and the fluorescence intensity decreased with the reduction of pH. In addition, an excellent linear relationship with pH value in the range of 1.0 ∼ 5.0 was achieved. As we all known that glucose can be catalyzed by glucose oxidase to produce gluconic acid and hydrogen peroxide, in which a good deal of protons were produced and the pH was gradually lowered. Since CsPbBr3@SiO2 was stable to water and oxygen, and sensitive to ambient pH, we applied CsPbBr3@SiO2 to the detection of glucose. CsPbBr3@SiO2 showed fantastic selectivity and sensitivity to glucose, and the detection limit can even reach 18.5 μM. Furthermore, CsPbBr3@SiO2 was successfully applied to the detection of glucose in the human serum with satisfactory performance.

Genomic Analysis of Pseudomonas asiatica JP233: An Efficient Phosphate-Solubilizing Bacterium.

The bacterium Pseudomonas sp. strain JP233 has been reported to efficiently solubilize sparingly soluble inorganic phosphate, promote plant growth and significantly reduce phosphorus (P) leaching loss from soil. The production of 2-keto gluconic acid (2KGA) by strain JP233 was identified as the main active metabolite responsible for phosphate solubilization. However, the genetic basis of phosphate solubilization and plant-growth promotion remained unclear. As a result, the genome of JP233 was sequenced and analyzed in this study. The JP233 genome consists of a circular chromosome with a size of 5,617,746 bp and a GC content of 62.86%. No plasmids were detected in the genome. There were 5097 protein-coding sequences (CDSs) predicted in the genome. Phylogenetic analyses based on genomes of related Pseudomonas spp. identified strain JP233 as Pseudomonas asiatica. Comparative pangenomic analysis among 9 P. asiatica strains identified 4080 core gene clusters and 111 singleton genes present only in JP233. Genes associated with 2KGA production detected in strain JP233, included those encoding glucose dehydrogenase, pyrroloquinoline quinone and gluoconate dehydrogenase. Genes associated with mechanisms of plant-growth promotion and nutrient acquisition detected in JP233 included those involved in IAA biosynthesis, ethylene catabolism and siderophore production. Numerous genes associated with other properties beneficial to plant growth were also detected in JP233, included those involved in production of acetoin, 2,3-butanediol, trehalose, and resistance to heavy metals. This study provides the genetic basis to elucidate the plant-growth promoting and bio-remediation properties of strain JP233 and its potential applications in agriculture and industry.

Protein cysteine S-glycosylation: oxidative hydrolysis of protein S-glycosidic bonds in aqueous alkaline environments

Some glycoproteins contain carbohydrates S-linked to cysteine (Cys) residues. However, relatively few S-glycosylated proteins have been detected, due to the lack of an effective research methodology. This work outlines a general concept for the detection of S-glycosylation sites in proteins. The approach was verified by exploratory experiments on a model mixture of β-S-glucosylated polypeptides obtained by the chemical transformation of lysozyme P00698. The model underwent two processes: (1) oxidative hydrolysis of S-glycosidic bonds under alkaline conditions to expose the thiol group of Cys residues; (2) thiol S-alkylation leading to thiol S-adduct formation at the former S-glycosylation sites. Oxidative hydrolysis was conducted in aqueous urea, dimethyl sulfoxide, or trifluoroethanol, with silver nitrate as the reaction promoter, in the presence of triethylamine and/or pyridine. The concurrent formation of stable protein silver thiolates, gluconic acid, and silver nanoclusters was observed. The essential de-metalation of protein silver thiolates using dithiothreitol preceded the S-labeling of Cys residues with 4-vinyl pyridine or a fluorescent reagent. The S-labeled model was sequenced by tandem mass spectrometry to obtain data on the modifications and their distribution over the protein chains. This enabled the efficiency of both S-glycosidic bonds hydrolysis and S-glycosylation site labeling to be evaluated. Suggestions are also given for testing this novel strategy on real proteomic samples.

Multi-strategy in production of high titer gluconic acid by the fermentation of concentrated cellulosic hydrolysate with Gluconobacter oxydans

Cellulosic hydrolysate from the hydrolysis of glucan-riched biomass can offer abundantly bioavailable glucose, which is an alternative feedstock for gluconic acid production. In order to speed up the process of cellulosic-based gluconic acid synthesis industrialization, cost reduction by using efficient substrate in batch-fermentation with high yield and productivity is extremely important. However, enriched glucose obtained by concentrating enzymatic hydrolysate inevitably ascends the viscosity, resulting in a lower oxygen transfer rate that cannot meet the requirement of bio-oxidation with Gluconobacter oxydans , resulting in gluconic acid productivity decreased drastically once the glucose content in the concentrated enzymatic hydrolysate was over 240 g/L with corresponding viscosity over 4 mPa·s. In view of the above problems, a combined strategy of activated carbon treatment and high-tension oxygen supply was applied to improve efficiency. Finally, approximately 230 g/L gluconic acid with 9.6 g/L/h productivity was achieved, which enabled the industrial-scale gluconic acid bio-production from cellulosic materials . • COS-SSB system can efficiently enhance the oxygen transfer rate and productivity. • CEH contain 240 g/L glucose could be used for GA production after AC treatment. • 231 g/L GA with 9.6 g/L/h productivity was achieved in CEH by combined strategy.

Silver nanoparticles@metal-organic framework as peroxidase mimics for colorimetric determination of hydrogen peroxide and blood glucose

• A colorimetric strategy for sensitive detection of H 2 O 2 and glucose has been developed. • A broad dynamic response range for glucose in the range from 0.5 to 50 μM with a limit of detection of 0.23 μM. • The proposed method can be used to monitor glucose in human serum samples. As a major origin of energy for cellular activity and intermediates product of metabolism, glucose plays a significant role in biological activity. Thus, it is relatively vital to explore a sensitive and accurate approach to monitor blood glucose. Herein, a colorimetric biosensor for sensitive, rapid, and reliable monitoring of blood glucose was successfully established. In this sensing system, a nanocomposite of silver nanoparticles (AgNPs) depositing on the MIL-101 (Fe) surface (AgNPs@MOF) was employed as an excellent peroxidase mimic. Glucose could be effectively catalyzed by glucose oxidase (GOx) to produce hydrogen peroxide (H 2 O 2 ) and gluconic acid. Afterward, the AgNPs@MOF nanozyme catalyzed the oxidation of the colorless material TMB into the blue product oxTMB by H 2 O 2 , causing a noticeable change in absorbance at 652 nm. A colorimetric glucose measurement platform was proposed with preferable simplicity and high sensitivity using GOx and AgNPs@MOF nanozyme that with peroxidase-mimicking activity. The limit of detection of the established biosensor was down to 0.17 μM for H 2 O 2 and 0.23 μM for glucose. More importantly, as a result of the application of this biosensor with human blood samples, glucose levels could be monitored with high accuracy, which indicated that this approach had great potential for diabetes therapy. A colorimetric biosensor for sensitive, rapid, and reliable monitoring of blood glucose was successfully established. In this sensing system, a nanocomposite of silver nanoparticles (AgNPs) depositing on the MIL-101 (Fe) surface (AgNPs@MOF) was employed as an excellent peroxidase mimic. Glucose could be effectively catalyzed by glucose oxidase (GOx) to produce hydrogen peroxide (H 2 O 2 ) and gluconic acid. Afterward, the AgNPs@MOF nanozyme catalyzed the oxidation of the colorless material TMB into the blue product oxTMB by H 2 O 2 , causing a noticeable change in absorbance at 652 nm.

Cyclic enhancement of hypoxic microenvironment via an intelligent nanoamplifier for activated NIR-II fluorescence/photoacoustic imaging-guided precise synergistic therapy.

Tumor microenvironment (TME)-activated theranostics is a promising strategy to effectively identify small lesions, improve antitumor efficacy, and reduce the risk of undesired side effects. Hypoxia, as a common characteristic of TME, can serve as a preferred site for stimulus-dependent activation; however, tumor-hypoxia levels in various developmental stages exhibit different characteristics, severely limiting the response sensitivity. Herein, a circulating self-reinforcing hypoxic nanoamplifier (CGH NAs) is developed that utilizes a dual-chain reaction process (internal regulation, internal regulation) to achieve precise activation of NIR-II FL/photoacoustic (PA) imaging-guided synergistic therapy. Inspired by the positive correlation of nitroreductase (NTR) with hypoxia, the CGH NAs encapsulate CQ4T and GOx into NTR-sensitive hyaluronic acid-nitroimidazole (HA-NI) shell via a self-assembly approach, enabling aggregation-caused NIR-II FL quenching and tumor-accurate delivery. When CGH NAs efficiently accumulated in the tumor region, the intensive local NTR reduced hydrophobic -NO2 to hydrophilic -NH2, which lead to disassembly of CGH NAs. The released GOx could consume O2 (internal regulation) and glucose to cut off the energy supply, inducing tumor-starvation therapy; generate gluconic acid and H2O2 (oxidative stress). Meanwhile, the released CQ4T promoted rapid recovery of NIR-II FL signals for imaging-guided PDT, which could simultaneously deplete intratumoral O2 (external stimulation). Remarkably, the strengthened tumor-hypoxia levels in turn accelerated the NTR-responsive degradation of the CGH NAs, thereby achieving high-efficiency theranostic.

Na2S2O4@Co-metal organic framework (ZIF-67) @glucose oxidase for biofilm-infecting wound healing with immune activation

In recent years, photodynamic therapy (PDT) or chemodynamic therapy (CDT) based on the antimicrobial property or anti-biofilm property of reactive oxygen species (ROS) have been widely recognized for their low susceptibility to microbial resistance. However, due to the complication of the three-dimensional structure of the biofilm at the wound site and the high quenching rate of common ROS, the treatment with traditional ROS could not achieve satisfactory wound healing effects. Here, Na2S2O8@ZIF-67/GOx nanoparticles (NZG NPs) were prepared as a new high-toxic ROS nanogenerator for application of biofilm-infecting wound healing with the assistance of glucose oxidase (GOx) for amplified CDT and immune activation. When the NZG NPs entered the biofilm, Co-based metal organic frame (ZIF-67) ruptured in the acidic microenvironment, which induced the release of GOx and the production of gluconic acid and H2O2, further promoting the decrease of pH of the biofilm microenvironment and in turn accelerating the cleavage of ZIF-67 and the release of Na2S2O8. Then, S2O82− could gradually transformed into high-toxic sulfate radical (SO4−), part of which further produced OH in situ with H2O, thereby inhibiting the proliferation of bacteria and biofilms. Interestingly, these two types of ROS not only caused direct damage to the biofilm, but also activated the immune system of the wound site as well as the body more effectively, which also played an indirect role in promoting biofilm destruction and wound healing. In vitro and in vivo results showed that, as a new high-toxic ROS nanogenerator, the NZG NPs supply amplified chemodynamic therapy and immune activation to destroy biofilms, but also achieve effective wound healing without causing bacterial tolerance, which provides a new strategy for the development of biofilm-infecting wound healing.

Plasma Metabolites Link Dietary Patterns to Stroke Risk.

While dietary intake is linked to stroke risk, surrogate markers that could inform personalized dietary interventions are lacking. We identified metabolites associated with diet patterns and incident stroke in a nested cohort from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study. Levels of 162 metabolites were measured in baseline plasma from stroke cases (n = 1,198) and random controls (n = 904). We examined associations between metabolites and a plant-based diet pattern previously linked to reduced stroke risk in REGARDS. Secondary analyses included 3 additional stroke-associated diet patterns: a Mediterranean, Dietary Approaches to Stop Hypertension (DASH), and Southern diet. Metabolites were tested using Cox proportional hazards models with incident stroke as the outcome. Replication was performed in the Jackson Heart Study (JHS). Inverse odds ratio-weighted mediation was used to determine whether metabolites mediated the association between a plant-based diet and stroke risk. Metabolites associated with a plant-based diet included the gut metabolite indole-3-propionic acid (β = 0.23, 95% confidence interval [CI] [0.14, 0.33], p = 1.14 × 10-6 ), guanosine (β = -0.13, 95% CI [-0.19, -0.07], p = 6.48 × 10-5 ), gluconic acid (β = -0.11, 95% CI [-0.18, -0.04], p = 2.06 × 10-3 ), and C7 carnitine (β = -0.16, 95% CI [-0.24, -0.09], p = 4.14 × 10-5 ). All of these metabolites were associated with both additional diet patterns and altered stroke risk. Mediation analyses identified guanosine (32.6% mediation, p = 1.51 × 10-3 ), gluconic acid (35.7%, p = 2.28 × 10-3 ), and C7 carnitine (26.2%, p = 1.88 × 10-2 ) as mediators linking a plant-based diet to reduced stroke risk. A subset of diet-related metabolites are associated with risk of stroke. These metabolites could serve as surrogate markers that inform dietary interventions. ANN NEUROL 2023;93:500-510.

Impact of temperature on gluconic acid production during acetification by Acetobacter aceti.

The current approach to gluconic acid production is acetification at 30°C, a temperature that can be difficult to maintain in tropical countries. This study investigated the production of gluconic acid during acetification by Acetobacter aceti WK at high temperatures. An acid-tolerant and thermotolerant species, A. aceti WK, was used for acetification at three different temperatures, namely, 30°C (normal temperature), 37°C, and 40°C (high temperature). Acetification was performed in a 100L bioreactor with 0.15% CaCl2 for protection of the cells against high temperatures. The production of the organic acids, that is, acetic acid, gluconic acid, 2-keto gluconic acid, glucuronic acid, citric acid, succinic acid, lactic acid, and formic acid, was analyzed. Under acetification in the target total concentration of 80g/L, the highest acetic acid content (39.3g/L) was obtained at 37°C with an acetification rate of 0.3013g/L/h, while the acetic acid content and acetification rate achieved at 30°C were 31g/L and 0.3089g/L/h, respectively. Additionally, gluconic acid presented at the highest concentration of 2.17g/L. The rate of production of gluconic acid was 0.0169g/L/h at 37°C. This acetification process at 37°C will be valuable as an alternative source for gluconic acid production for commercial applications.

Nanocellulose coated paper diagnostic to measure glucose concentration in human blood.

A new generation of rapid, easy to use and robust colorimetric point of care (POC) nanocellulose coated-paper sensors to measure glucose concentration in blood is presented in this study. The cellulose gel containing the enzyme with co-additive is coated and dried onto a paper substrate. Nanocellulose gel is used to store, immobilize and stabilize enzymes within its structure to prolong enzyme function and enhance its availability. Here, we immobilize glucose oxidase within the gel structure to produce a simple colorimetric blood glucose sensor. Increase in blood glucose concentration increases the concentration of reaction product which decreases the system pH detected by the pH indicative dye entrapped in the nanocellulose gel. The sensor produces a color change from red to orange as pH decreases due to the enzymatic reaction of glucose into gluconic acid and hydrogen peroxide. This sensor can measure glucose concentrations of 7-13mM (medical range for diabetes control) at temperatures of 4°C-40°C. Stability tests confirm that no denaturation of enzyme occurs by measuring enzyme activity after 4weeks. A prototype device is designed to instantly measure the glucose concentration from blood in a two steps process: 1) red blood cell separation and 2) quantification of glucose by color change. This study demonstrates nanocellulose sensor as an economical, robust, and sensitive diagnostic technology platform for a broad spectrum of diseases.

Metabolite variations of sugars, organic acids, fatty acids and amino acids in flower buds of Zingiber mioga Roscoe at different developmental stages

Z. mioga is favoured by consumers for its unique spicy flavour, in which sugars, organic acids, fatty acids and amino acids have a great influence on its flavour formation. Therefore, the characteristic changes in relative contents of sugars, organic, amino and fatty acids in flower buds of Z. mioga at four developmental stages (DS1-DS4) were studied. The results indicated that the contents of total sugars, organic acids, total essential amino acids and total fatty acids were the highest at the stages of DS1, DS3, DS4 and DS4, respectively. According to the results of principal component analysis (PCA), Z. mioga at DS1-DS4 stages can be well separated and showed significant differences. Among those primary metabolites, the gluconic acid, sucrose, fructose-1,6-biphosphate, glucose-6-phosphate, glucose-1-phosphate and glucosamine in sugars, the glyceraldehyde-3-phosphate, malonic acid, succinic acid, aminomalonic acid and quinic acid in organic acids, the cycloleucine, L-aspartic acid, L-arginine and L-methionine, L-proline, L-valine and L-phenylalanine in amino acids, and the10-heptadecenoic acid, myristic acid, linoleic acid, undecylic acid and stearic acid in fatty acids played a major role in these changes in the formation of ginger flavour during its growth.

Changes in sugar, organic acid and free amino acid levels and the expression of genes involved in the primary metabolism of oleocellosis in citrus peels

Oleocellosis is a physiological disorder in citrus fruit and causes extensive economic damage due to the surface blemishes it creates. It was reported that oleocellosis always occurs during preharvest maturation and postharvest storage. In the present study, the oleocellosis incidence of Jincheng orange, Navel orange and Ponkan were found to be different during preharvest maturation, however, no differences were found during postharvest storage. Additionally, it was interesting that the outbreak period of oleocellosis incidence was 0–12 d during postharvest storage. Climate change has been reported as a factor promoting oleocellosis development. However, little information is available regarding how primary metabolites and the expression of genes involved in sugar, organic acid and free amino acid metabolism in citrus change to adjust to new environments. Metabolic profiling obtained by gas chromatography-mass spectrometry (GC‒MS) and amino acid analysis showed that the accumulations of fructose, glucose, sucrose, maltose, mannose, citric acid, α-ketoglutarate, 2-keto-d-gluconic acid, glutamate, valine, glycine and threonine might play major roles in adaptation to changes in oleocellosis peels for three types of citrus fruit. However, decreased contents of malic acid, gluconic acid and proline were observed, possibly due to consumption in energy metabolism or reflecting a unique characteristic in this disorder. Regarding gene expression in primary metabolism pathways obtained by high-throughput mRNA sequencing (RNA-Seq) technology, upregulated genes encoding alpha-glucosidase, beta-glucosidase, beta-fructofuranosidase, alpha-amylase, beta-amylase, malate dehydrogenase, CTP synthase (glutamine hydrolysing), serine-glyoxylate transaminase, serine/glycine hydroxymethyltransferase and proline dehydrogenase were the main changes in this disorder.

Therapeutic Potential of Honey and Propolis on Ocular Disease

Honey and propolis have recently become the key target of attention for treating certain diseases and promoting overall health and well-being. A high content of flavonoids and phenolic acids found in both honey and propolis contributes to the antioxidant properties to scavenge free radicals. Honey and propolis also exhibited antibacterial effects where they act in two ways, namely the production of hydrogen peroxide (H2O2) and gluconic acids following the enzymatic activities of glucose oxidase, which exerts oxidative damage on the bacteria. Additionally, the anti-inflammatory effects of honey and propolis are mainly by reducing proinflammatory factors such as interleukins and tumor necrosis factor alpha (TNF-α). Their effects on pain were discovered through modulation at a peripheral nociceptive neuron or binding to an opioid receptor in the higher center. The aforementioned properties of honey have been reported to possess potential therapeutic topical application on the exterior parts of the eyes, particularly in treating conjunctivitis, keratitis, blepharitis, and corneal injury. In contrast, most of the medicinal values of propolis are beneficial in the internal ocular area, such as the retina, optic nerve, and uvea. This review aims to update the current discoveries of honey and propolis in treating various ocular diseases, including their antioxidant, anti-inflammatory, antibacterial, and anti-nociceptive properties. In conclusion, research has shown that propolis and honey have considerable therapeutic promise for treating various eye illnesses, although the present study designs are primarily animal and in vitro studies. Therefore, there is an urgent need to translate this finding into a clinical setting.

Hydrolytic Oxidation of Cellobiose Using Catalysts Containing Noble Metals

Studies of the processes of the hydrolytic oxidation of disaccharides are the first step towards the development of technologies for the direct conversion of plant polysaccharides, primarily cellulose, into aldonic and aldaric acids, which are widely used in chemical synthesis and various industries. In this study, heterogeneous catalysts based on a porous matrix of hypercrosslinked polystyrene (HPS) and noble metals (Pt, Au, Ru, and Pd) were proposed for the hydrolytic oxidation of cellobiose to gluconic and glucaric acids. The catalysts were characterized using low-temperature nitrogen adsorption, hydrogen chemisorption, electron microscopy, and other methods. In particular, it was shown that the Pt-containing catalyst contained, on average, six times more active centers on the surface, which made it more promising for use in this reaction. At a temperature of 145 °C, an O2 pressure of 5 bars, and a substrate/catalyst weight ratio of 4/1, the yields of gluconic and glucaric acids reached 21.6 and 63.4%, respectively. Based on the data obtained, the mathematical model of the cellobiose hydrolytic oxidation kinetics in the presence of 3% Pt/HPS MN270 was developed, and the parameter estimation was carried out. The formal description of the kinetics of cellobiose hydrolytic oxidation was obtained.

Role of Acetic Acid Bacteria in Food and Beverages.

Acetic acid bacteria (AAB) are microorganisms widely distributed in nature. Although this group is involved in the spoilage of some foods, AAB are of great industrial interest, and their functionality is still poorly understood. AAB convert ethanol, sugars and polyols into various organic acids, aldehydes and ketones via oxidative fermentation. These metabolites are produced during a succession of biochemical reactions in various fermented foods and beverages, such as vinegar, kombucha, water kefir, lambic and cocoa. Furthermore, important products such as gluconic acid and ascorbic acid precursors can be produced industrially from their metabolism. The development of new AAB-fermented fruit drinks with healthy and functional properties is an interesting niche for research and the food industry to explore, as it can meet the needs of a wide range of consumers. Exopolysaccharides such as levan and bacterial cellulose have unique properties, but they need to be produced on a larger scale to expand their applications in this area. This work emphasizes the importance and applications of AAB during the fermentation of various foods, their role in the development of new beverages as well as numerous applications of levan and bacterial cellulose.

Glucose Oxidase in Conjunction with Catalase – An Effective System of Wine pH Management in Red Wine

<h3>Background and goals</h3> High grape pH directly influences the quality of the subsequent wines. Acidulation of grape juice and grape must by tartaric acid is a common practice but can leave a wine’s flavor unbalanced. Treatment with commercially available Catazyme 25 L, which contains the enzymes glucose oxidase (GOx) and catalase, was investigated as a valid way to lower high pH in red grape juice/must while simultaneously increasing acidity and lowering glucose and potential alcohol. <h3>Methods and key findings</h3> Tempranillo must and juice were treated with Catazyme 25 L at two concentrations (0.5 g/L and 1 g/L) over a 24-hr period under continuous aeration. Chemical and sensory analyses were performed on the resulting wines. Results indicated that the pH of Tempranillo juice was decreased by 0.84 when using Catazyme 25 L at a rate of 1.0 g/L. Similarly, addition of Catazyme 25 L at 0.5 g/L decreased pH from 4.6 to 4.0 and 3.8 in the must and juice, respectively. Use of Catazyme 25 L led to production of lower alcohol wines due to conversion of glucose to gluconic acid. Sensory evaluation of the wines indicated a positive impact of the enzyme blend on color, aroma, and in-mouth flavor. <h3>Conclusions and significance</h3> GOx in conjunction with catalase is an effective pH management system, and of particular value for winemaking in hot climates, where it can also help lower alcohol concentration while positively impacting the sensory profiles of the wines.

The Effect of Dekkera bruxellensis Concentration and Inoculation Time on Biochemical Changes and Cellulose Biosynthesis by Komagataeibacter intermedius.

Bacterial Cellulose (BC) is a biopolymer with numerous applications. The growth of BC-producing bacteria, Komagataeibacter intermedius, could be stimulated by Dekkera bruxellensis, however, the effect on BC yield needs further investigation. This study investigates BC production and biochemical changes in the K. intermedius-D. bruxellensis co-culture system. D. bruxellensis was introduced at various concentrations (103 and 106 CFU/mL) and inoculation times (days 0 and 3). BC yield was ~24% lower when D. bruxellensis was added at 103 CFU/mL compared to K. intermedius alone (0.63 ± 0.11 g/L). The lowest BC yield was observed when 103 CFU/mL yeast was added on day 0, which could be compromised by higher gluconic acid production (10.08 g/L). In contrast, BC yields increased by ~88% when 106 CFU/mL D. bruxellensis was added, regardless of inoculation time. High BC yield might correlate with faster sugar consumption or increased ethanol production when 106 CFU/mL D. bruxellensis was added on day 0. These results suggest that cell concentration and inoculation time have crucial impacts on species interactions in the co-culture system and product yield.