Increase In Protein Content Research Articles

Preparation and characterization of a new food-grade Pickering emulsion stabilized by mulberry-leaf protein nanoparticles.

Food-grade Pickering particles, particularly plant proteins, have attracted significant interest due to their bio-based nature, environmental friendliness, and edibility. Mulberry-leaf protein (MLP) is a high-quality protein with rich nutritional value and important functional properties. It has special amphoteric and emulsifying characteristics, making it valuable for use in Pickering emulsions. This study aimed to investigate the feasibility of using MLP nanoparticles as solid particles to stabilize Pickering emulsions. The particle size of MLP nanoparticles was less than 300 nm under neutral and alkaline conditions. At pH 9, the zeta potential value reached -34.3 mV, indicating the electrostatic stability of the particles. As ion concentration increased, the particle size of MLP nanoparticles increased, and the zeta potential decreased. Throughout the storage process, no obvious aggregation or precipitation was observed in the dispersion of MLP nanoparticles, indicating strong stability. The particle size of the Pickering emulsion decreased with the increase in protein concentration. When the protein concentration was low, the particles on the oil-water interface became sparse, resulting in poor stability of the prepared emulsion and making it susceptible to aggregation and thus larger particle sizes. Increasing the oil-phase ratio to 70% (v/v) promotes the formation of Pickering emulsions, which exhibit exceptional stability when MLP nanoparticles are fixed at a concentration of 20 mg mL-1. The overall findings indicated that MLP nanoparticles have potential as food-grade materials for Pickering emulsions, marking a novel application of these nanoparticles in the food industry. © 2024 Society of Chemical Industry.

Compound extreme heat and drought stress alter the spatial gradients of protein and starch in wheat grains

The spatial gradients of protein and starch in wheat grains affected the grain milling characteristics and flour utilization. The increase in compound heat stress and drought stress (HDS) due to global climate change threatens wheat grain yield and quality parameters, but the impacts of extreme climate events on the gradients of protein and starch in wheat grains remain unclear. In this study, two-year, environment-controlled experiments with four heat stress levels (17/27, 21/31, 25/35, and 29/39°C) and three drought stress levels (30 %, 55 %, and 75 % field capacity) were conducted to investigate the effects of HDS on the gradients of protein and starch concentrations within the five grain layers. The results showed that HDS resulted in significantly greater protein concentrations, while resulting in lower starch concentrations in the wheat grain layers. Among the five layers, the endosperm layers exhibited the greatest increase in protein concentration under HDS, but the starch concentration under HDS decreased in the order of husk > aleurone > endosperm layer. HDS unevenly altered the protein and starch concentrations of the five grain layers. There was significant linear relationship between relative protein and starch concentration with accumulated heat degree days (AHDD). With a 1°C·d increase in AHDD, the protein concentration in the five grain layers increased by 1.17–2.19 %, while the starch concentration decreased by 0.62–0.90 %, depending on the drought stress levels. A significant linear relationship was also observed between the relative protein and starch concentrations and evapotranspiration (ET). A 1 mm increase in ET led to a protein concentration decrease of 0.58–0.76 % in P1-P5, with a corresponding starch concentration increase of 0.28–0.46 %, depending on cultivar and treatment stages. Our results indicate that HDS significantly impacts the grain quality parameters for the flour milling process and human diet and will provide important insights into adapting wheat quality to climate change.

Plant-based marbled salami analogs: Emulsion-loaded microgels embedded within protein-polysaccharide hydrogel matrices

The inherent molecular differences between plant and animal proteins make it challenging to accurately simulate the optical and mechanical properties of real meat products using plant-derived ingredients. Soft matter physics approaches are therefore being employed to direct the assembly of plant proteins, polysaccharides, and lipids into meat-like structures. The main focus of the current study was to use soft matter physics approaches to create plant-based analogs of marbled meat products, such as salami, chorizo, or pepperoni. These products have whitish fatty regions embedded within reddish/brown lean regions. In this study, we mimicked the fatty regions in salami using emulsion-loaded alginate beads and the lean regions using composite hydrogels assembled from potato protein and gellan gum. Initially, the textural attributes of the plant-based lean regions were optimized by varying potato protein type (low or high isoelectric point) and concentration. As expected, the mechanical strength of the lean region analogs increased with increasing protein content and depended on protein type. Introducing alginate beads into the salami analogs had little impact on their textural attributes when measured under compression conditions but decreased their stiffness and fracture stress when measured under tensile conditions. In particular, introducing either small or large beads reduced the stiffness and breaking stress of the salami analogs, which was attributed to the introduction of weak points in the composite hydrogel. Finally, we showed that the appearance and textural attributes of real salami could be mimicked in plant-based salami by optimizing its composition and structure. This research provides valuable insights into methods of better simulating the properties of marbled meat products, like sausages and cold-cut meat products, thereby creating a more sustainable food supply.

Optimization and Development of Bacopa monnieri Infused Nutri-cereals Pizza Base

Background: Pizza, an Italian culinary delight, is relished by diverse groups of individuals. In this study, pizza base was innovatively crafted by substituting refined wheat flour (RWF) by combining with little millet flour (LMF) and proso millet flour (PMF) along with Bacopa monneri. Methods: A meticulous investigation was conducted to assess the impact of different quantities of RWF (20-40 g), LMF (20-40 g) and PMF (20-40 g) on the quality attributes of the pizza base, using a D-optimal design for optimization. Result: The findings revealed that an increased proportion of refined wheat flour (RWF) enhanced the overall acceptability of the pizzabase. Further more, the hardness of the pizzabase was influenced by higher RWF quantities and reduced levels of proso millet flour (PMF) and little millet flour (LMF). Similarly, an increase in the amount of PMF led to a significant increase in both protein and antioxidant content. The optimized proportions for RWF, LMF and PMF were determined to be 40 g, 33.3334 g and 26.6666 g, respectively. This optimization yielded the following outcomes: an overall acceptability score of 8.33, an antioxidant content of 92.2727%, a pizza base texture (hardness) of 2388.88 g and a protein content of 10.3131%. These results are in concurrence with the predictions made by the significantly (p less than 0.05) fitted quadratic models.

The Effect of Tillage Systems and Weed Control Methods on Grain Yield and Gluten Protein Compositional and Content-Related Changes in Hybrid Bread Wheat

The use of simplified tillage systems and weed control methods using reduced herbicide doses in wheat production technology is one of the basic requirements of sustainable agriculture in terms of obtaining high-quality grain of this species. The aim of three-year field studies was to determine the yield and quality characteristics of hybrid wheat grain depending on two tillage systems (CT and RT) and four weed control methods: mechanical (M) and mechanical–chemical, using recommended herbicide doses (MH100) and doses reduced by 25 and 50% (MH75, MH50). A comparable grain yield, number of grains per spike, weight of one thousand wheat grains, and amount of gluten and ω gliadin subunits (GLI) were obtained in the RT and CT systems. The CT system increased protein content (by 15.2 g kg−1) and the increase in the sum of gluten protein fractions was higher for glutenins (GLU) and their LMW and HMW subunits (from 20.9 to 29.8%). The application of the method with the recommended herbicide dose (MH100), compared to M and MH50, resulted in an increase in grain yield by 0.89 and 1.04 t ha−1, respectively, as well as in the sum of GLI (by 8.4 and 12.3%) and GLU (by 13.7 and 25.3%). The application of the herbicide dose reduced by 25% (MH75) compared to the recommended dose (MH100), especially in the RT system, did not cause a significant decrease in protein content and the amount of GLI and GLU, while reducing grain yield (by 0.26 t ha−1) and the amount of gluten (by 3.1%).

Proximate Composition and Functional Properties of Soyabeans (Glycine Max) Enriched Carbohydrate Diets

This study explored enhancing the nutritional value and functional properties of carbohydrate-rich diets by incorporating soybeans into millet, cassava, and yam. Soybeans, known for their high protein, unsaturated fats, and micronutrients, were used to fortify these staple foods. Proximate analysis assessed the macronutrient content of both the original and soybean-enriched samples, while functional properties such as water and oil absorption capacities, swelling index, bulk density, and gelation capacity were evaluated. Results showed significant increases in protein content, particularly in the millet-soybean mixture (29.81%), with relatively low levels of fat and ash. Functional assessments indicated millet’s highest gelation capacity and cassava’s superior water absorption. These findings suggest that soybean fortification can improve carbohydrate-rich diets’ nutritional quality and versatility. Further research is recommended to assess the impact of these dietary modifications on human health and consumer acceptance.

Process optimization and characteristics of enzymatically cross-linked and ultrafiltrated whey

Whey, a byproduct of cheese production, is valued for its high-quality proteins. Ultrafiltration concentrates these proteins but faces challenges such as membrane fouling. This study investigates the use of transglutaminase to improve ultrafiltration efficiency by reducing fouling and optimizing protein recovery. Whey was divided into samples of whey in natura (WIN) and whey partially demineralized (WPD). Both were treated with different concentrations of transglutaminase (0, 0.5, 1.5, and 2.5% relative to protein mass) and ultrafiltered using polyethersulfone membranes at 4 bar. Effectiveness was evaluated by permeate flux and protein concentration, as well as physicochemical and structural characterizations such as FTIR, TGA, and molecular weight analysis. Transglutaminase reduced membrane fouling, increasing permeate flux. The 2.5% enzyme concentration was most efficient for WIN, while 1.5% was ideal for WPD. Enzymatic treatment increased protein concentration and thermal stability of the concentrates. FTIR analysis indicated the formation of cross-links between proteins. Molecular weight analysis revealed larger and more stable protein aggregates, improving ultrafiltration performance. This study suggests that transglutaminase is promising for optimizing whey ultrafiltration, improving protein recovery and process efficiency, with potential large-scale application in the food industry.

Perspectives on optimizing microalgae cultivation: Harnessing dissolved CO2 and lactose for sustainable and cost-efficient protein production

Microalgae, known for their land-sparing cultivation and remarkable photosynthetic efficiency, play a crucial role in advancing sustainable development goals. This study explored the use of cost-effective inorganic carbon (the ionic form of CO2) and organic carbon sources (lactose, a primary sugar in whey wastewater) to support the growth of Chlorellasorokiniana UTEX 1230, and improved protein content through nitrogen supply optimization. NaHCO3 proved to be more effective than Na2CO3, resulting in a 3.4-fold increase in biomass concentration, with an initial 5 mM HCO3‾ concentration compared to the basal medium. Further addition of 0.75 % lactose led to a 4.05-fold increase in biomass concentration, with the maximum specific growth rate at 1.28/d, maximum biomass concentration at 695.88 mg/L, and maximum biomass productivity at 250.91 mg/L/d. Nitrogen supplementation greatly increased protein concentration from 16.41 % (250 mg/L NaNO3) to 52.95 % (1000 mg/L NaNO3). These results support the potential for utilizing whey wastewater bioremediation to produce high-value protein via microalgal cultivation.

Influence of Germination Time on the Morphological, Structural, Vibrational, Thermal and Pasting Properties of Potato Starch from Solanum tuberosum Phureja Group

AbstractThis work focuses on the study of the physicochemical changes that take place during a short germination period in flours and starches of the Creole potato tuber. To this end, the changes in the composition of flours and the structural, thermal, vibrational, functional and pasting changes of the isolated starches from germinated potatoes were evaluated during the 12-day germination period, measured every 4 days. The water absorption index (WAI) and the swelling powder showed no significant changes. Germination resulted in a decrease in fat and ash content, but an increase in protein and amylose content. Scanning electron microscopy (SEM) showed no changes in the morphology of the starch during germination. X-ray diffraction showed that isolated Creole potato starch contains nanocrystals with hexagonal crystal structure, which are not affected by germination. Differential scanning calorimetry (DSC) shows a shift of the gelatinization peak to the right, which could be attributed to the concentration effect. The pasting profiles of the isolated starches show no significant changes, indicating that the starch granules do not suffer any external damage due to the enzymatic process during germination and that the final viscosity behaves like a hydrogel.

Non-CG DNA hypomethylation promotes photosynthesis and nitrogen fixation in soybean

Non-CG DNA methylation, a plant-specific epigenetic mark mainly regulated by chromomethylase (CMT), is known to play important roles in Arabidopsis thaliana. However, whether and to what extent non-CG DNA methylation modulates agronomic traits in crops remain to be explored. Here, we describe the consequences of non-CG DNA hypomethylation on development, seed composition, and yield in soybean (Glycine max). We created a Gmcmt mutant line lacking function of all four CMT genes. This line exhibited substantial hypomethylation of non-CG (CHG and CHH) sites. Non-CG hypomethylation enhanced chromatin accessibility and promoted or repressed the expression of hundreds of functionally relevant genes, including upregulation of GOLDEN-LIKE 10 (GmGLK10), which led to enhanced photosynthesis and, unexpectedly, improved nitrogen fixation efficiency. The Gmcmt line produced larger seeds with increased protein content. This study provides insights into the mechanisms of non-CG methylation-based epigenetic regulation of soybean development and suggests viable epigenetic strategies for improving soybean yield and nutritional value.

Digestive utilization of Sahelian forages associated with cowpea haulms (Vingna unguiculata) and blood profile in Arabic rams

Digestive utilization of sahelian forages associated with Vingna unguiculata and blood profile study was conducted in scientific garden of the University of Sciences and Technology, Ati (JSUSTA). Three forages were used to assess in vivo digestibity in eighteen (18) rams weighing around 31.83±3.02 kg and displayed individually in metabolic cages in six (6) groups of three (3) animals. Control groups received 1000g of feed made up of Brachiaria deflexa, Dactyloctenium aegyptium and Echinocloa colona. While, experimental groups received basal feeds associated with 30% of Vingna unguiculata. The experiment was preceded by 14 days adaptation and 7 days of data collection during which, hundred (100g) grams of feeds and feces as well as urine (10 ml) were collected for chemical analysis and digestibility assessment. At the end of experimentation, two (2) ml of blood was collected from each animal before and after feeding for blood profile analysis. The results showed that the association of 30% Vingna unguiculata have significantly (p<0.05) increased intake of D. aegyptium and B. deflexa in Arab rams. In vivo digestibility of E. colona was significantly (p<0.05) higher in rams when associated or no with 30% of Vingna unguiculata. Blood profile analysis showed that E. colona associated with 30% of Vingna unguiculata induced significant (p<0.05) increase in blood protein, globulin and cholesterol concentration in Arabic rams.

HIV-1 Gag Polyprotein Affinity to the Lipid Membrane Is Independent of Its Surface Charge.

The binding of the HIV-1 Gag polyprotein to the plasma membrane is a critical step in viral replication. The association with membranes depends on the lipid composition, but its mechanisms remain unclear. Here, we report the binding of non-myristoylated Gag to lipid membranes of different lipid compositions to dissect the influence of each component. We tested the contribution of phosphatidylserine, PI(4,5)P2, and cholesterol to membrane charge density and Gag affinity to membranes. Taking into account the influence of the membrane surface potential, we quantitatively characterized the adsorption of the protein onto model lipid membranes. The obtained Gag binding constants appeared to be the same regardless of the membrane charge. Furthermore, Gag adsorbed on uncharged membranes, suggesting a contribution of hydrophobic forces to the protein-lipid interaction. Charge-charge interactions resulted in an increase in protein concentration near the membrane surface. Lipid-specific interactions were observed in the presence of cholesterol, resulting in a two-fold increase in binding constants. The combination of cholesterol with PI(4,5)P2 showed cooperative effects on protein adsorption. Thus, we suggest that the affinity of Gag to lipid membranes results from a combination of electrostatic attraction to acidic lipids, providing different protein concentrations near the membrane surface, and specific hydrophobic interactions.

Effects of stress metabolism on physiological and biochemical reaction and polycyclic aromatic hydrocarbons degradation ability of Bacillus. sp

A strain of Bacillus licheniformis T5 was isolated from soil contaminated with crude oil due to its efficient degradation of polycyclic aromatic hydrocarbons (PAHs). When subjected to stress metabolism using phenanthrene as a carbon source, significant changes were observed in T5 cells. Infrared spectrum analysis revealed the presence of -C=C- and Ph-O-C (aromatic) groups on the bacterial surface, facilitating the adsorption of PAHs on the phospholipid layer and causing damage to the cell membrane. Scanning electron microscope (SEM) analysis showed the changes of cell morphology, including a large number of folds on the lower surface and the folding of cell membrane. Transmission electron microscope (TEM) observation showed that non-stressed bacteria with adequate nutritional conditions accumulated more lipids. However, the stress group contained more protein. It was found that stress metabolism led to the increase of protein content in T5 cells by 16.4% and the activity of oxidoreductase more than doubled. These physiological and biochemical changes enhance the ability of stressed bacteria to degrade PAHs efficiently, thereby reducing the degradation cycle. The findings offer valuable insights for the remediation of PAHs pollution.

Breeding wheat for organic farming: Can the high grain protein gene Gpc-B1 help to tackle challenges in view of end-use quality?

Organic farming contributes to sustain healthy ecosystems, but challenges such as lower crop yields and supply of the nitrogen needs of crops remain. Wheat is the most important organic arable crop in Europe and grain protein content is the main quality trait also for grading organic wheat despite that high baking quality can be also realized at lower protein contents. Hence, breeding of organic wheat varieties that realize a stable high grain protein content even at lower nitrogen availability is of utmost importance to guarantee income of organic wheat growers. A major QTL for high grain protein content was identified in wild emmer and transferred into bread wheat. We tested six different wheat genetic backgrounds varying for the presence/absence of the functional Gpc-B1 allele in multi-location trials in Central Europe for their performance under organic growing. The increase in grain protein content caused by the functional Gpc-B1 allele was present in almost all genetic backgrounds, however, was not consistent across all tested quality traits. None the less, the functional Gpc-B1 allele may play a major role to increase the stability of organic wheat to reach minimum requirements by traders and processors with respect to grain protein content.

Oryza glumaepatula and calcium oxide nanoparticles enhanced Cr stress tolerance by maintaining antioxidant defense, chlorophyll and gene expression levels in rice

Chromium (Cr), a potent heavy metal, threatens rice cultivation due to its escalating presence in soil from human activities. Wild rice contains useful genes for phytoremediation; however, it is difficult to use directly for metal mitigation. Here, a single segment substitution line (SSSL), SG001, was developed by crossing O. glumaepatula and Huajingxian74 (HJX) to evaluate the survival ability of plants against Cr. Further, we explored the potential effect of calcium oxide nanoparticles (CaO-NPs) (50 μM) to minimize the toxic effect of Cr (100 μM) in rice cultivars, SG001 and HJX. The findings of this study indicated that Cr toxicity led to increased oxidative stress. This was shown by higher levels of hydrogen peroxide (H2O2), which was increased by 104% in SG001 and 177% in HJX, and malondialdehyde (MDA) increased by 79% in SG001 and 135% in HJX. Furthermore, it also depicted that Cr toxicity considerably declined shoot and root length, shoot and root fresh weight by 30%, 27%, 25%, and 20% in SG001 and 44%, 51%, 42%, and 45% in HJX, respectively. This mitigation was evidenced by decreased Cr contents, increased calcium (Ca) levels in SG001, and the maintenance of chlorophyll, antioxidant defense, and gene expression levels. Moreover, there was a notable reduction in MDA and H2O2, while the defense mechanisms of key antioxidants, including ascorbate peroxidase, superoxide dismutase, glutathione, catalase, and peroxidase were upregulated, along with an increase in soluble protein contents in both rice cultivars after applying CaO-NPs. CaO-NPs effectively restored cellular and subcellular structural integrity and growth in both lines, which had been seriously disrupted by Cr toxicity. Overall, our findings suggest that SG001, in combination with CaO-NPs, could serve as an effective strategy to mitigate Cr toxicity in plants.

Effect of Arthrospira platensis (Spirulina) Fortification on Physicochemical, Nutritional, Bioactive, Textural, and Sensory Properties of Vegan Basil Pesto.

The high protein content of several microalgae species makes them an excellent addition to various food products, increasing their nutritional value. In this study, vegan basil pesto was designed and enriched with 1% and 2% Arthrospira platensis (spirulina). The pesto obtained was characterized by increased protein content (up to 40% more) and had a rich mineral composition, including up to three times more iron and 25% more calcium, among others. The increase of spirulina addition in the pesto also increased the content of polyphenols (up to 50% more) and flavonoids (up to 39% more). The fortified products had higher antioxidant activity against ABTS (up to 484.56 ± 2.16 μM Trolox/g) and DPPH (up to 392.41 ± 13.58 μM Trolox/g). The addition of spirulina will affect the hardness of the sauce, while in the other texture parameters (adhesiveness, springiness, and cohesion), there were no significant differences between the control and spirulina-fortified pesto. Although the pesto with spirulina was significantly darker in color (ΔE 8.83 and 12.05), consumers still rated it highly. All quality parameters of pesto with a 1% spirulina addition were rated the highest, contributing to the highest overall rating of the product (4.56). An increase in spirulina addition to 2% resulted in a decrease in the overall pesto rating (4.01), but still remains a good result compared to the control (4.22).

Rationing of diets of dairy cows for non-degradable protein with protein supplements of plant origin

Methods. This scientific and economic experiment was conducted under the conditions of the Moscow Region on 3 groups of Holstein breed cows showing milk yield of 8000 kg to study the efficiency of rationing of the content of non-degradable protein in feed rations for highly productive cows upon the use of various sources of protected plant-based protein.Results. It was found that the increase in content of non-degradable protein from 35% in the control group to 40% in experimental groups I and II for the period from day 21 until day 100 of lactation by feeding corn gluten (0.85 kg) and extruded soy protein concentrate (1.0 kg) accordingly instead of sunflower meal (1.2 kg) in the control group, with the similar concentration of raw protein of 17.2% in dry matter of the feed, contributed to the increase in milk yield with 4% fat content over 100 days of lactation by 6.3% and 8.5% (p ≤ 0.05) and the increase in feed costs (ME) by 5.3–6.7%. In physiological studies, an increase in the digestibility of crude protein by 2.0% and 3.2% abs (p ≤ 0.05), in groups of cows receiving protected protein supplements, as well as a tendency for more intensive digestion of crude fat by 1.2% and 2.2% abs. (p ≤ 0.1). Economic calculations showed that the use of the studied protein supplements in the diets of animals of experimental groups I and II made it possible to reduce the cost of 1 c of milk with basic fat content by 41.8 and 56.0 rubles, while receiving additional profit in the amount of 2845.1 and 3861.3 rubles compared to control.

Radiation synthesis of sodium alginate/gelatin based ultra-absorbent hydrogel for efficient water and nitrogen management in wheat under drought stress

The main focus of this study was on using radiation to make an ultra-absorbent hydrogel (UAH) from sodium alginate (SA) and gelatin (GL) biopolymers. This UAH can effectively handle water and nitrogen in wheat farming during drought stress. The hydrogel was synthesized by gamma irradiation-induced SA/GL/polyacrylamide crosslinking at 10–40 kGy. Varying SA/GL ratios affected swelling and the gel fraction of SA/GL/PAm hydrogels. The (SA/GL 17/83) hydrogel exhibited a 40.03 g/g swelling degree, while increasing SA content resulted in higher swelling, peaking at 75.5 g/g for (SA/GL 83/17). This indicated a synergistic interaction between SA and GL. The gel fraction also increased from 76.8 to 90.3%, with a higher GL content reflecting increased crosslinking. After multiple hydrolysis cycles, the hydrogel achieved 1293 (g/g) swelling and 36 days of water retention. When applied to wheat (Triticuma estivum) under drought stress, it significantly improved shoot length (18%), root length (43%), shoot fresh weight (49%), and shoot dry weight (51%) under extreme drought. The significant increases in protein and carbohydrate content in both shoots (up to 32% and 19%, respectively) and grains (up to 21% and 24%, respectively), along with the reduction in proline content (up to 38%), demonstrate that ultra-absorbent hydrogel (UAH) effectively enhances nitrogen content, photosynthesis, and overall plant health in wheat under varying drought stress levels. This novel SA/GL-based UAH holds promise for addressing water scarcity and agricultural challenges, offering a sustainable solution for water and nitrogen management under drought stress.

Cholesterol Efflux Decreases TLR4-Target Gene Expression in Cultured Macrophages Exposed to T. brucei Ghosts.

Trypanosoma brucei causes African trypanosomiasis in humans. Infection with T. brucei elicits a potent pro-inflammatory immune response within infected human hosts, and this response is thought to at least be partially due to Toll-like receptor (TLR) activation. In response to stimulation by lipopolysaccharide and other pathogen antigens, TLR4 translocates to lipid rafts, which induces the expression of pro-inflammatory genes. However, cholesterol efflux is acknowledged as anti-inflammatory due to promoting lipid raft disruption. In this study, we wanted to assess the impact of T. brucei "ghosts", which are non-viable T. brucei essentially devoid of intracellular contents, in stimulating macrophage TLR4 translocation to lipid rafts, and whether promoting cholesterol efflux in macrophages incubated with T. brucei ghosts attenuates TLR4-target gene expression. When cultured macrophages were exposed to T. brucei ghosts, we observed an increase in lipid raft TLR4 protein content, which suggests certain surface molecules of T. brucei serve as ligands for TLR4. However, pretreating macrophages with cholesterol acceptors before T. brucei ghost exposure decreased lipid raft TLR4 protein content and the expression of pro-inflammatory TLR4-target genes. Taken together, these results imply that macrophage cholesterol efflux weakens pro-inflammatory responses which occur from T. brucei infection via increasing macrophage lipid raft disruption.

Proteomic analysis of carbapenem-resistant Klebsiella pneumoniae outer membrane vesicles under the action of phages combined with tigecycline

BackgroundKlebsiella pneumoniae is the most commonly encountered pathogen in clinical practice. Widespread use of broad-spectrum antibiotics has led to the current global dissemination of carbapenem-resistant K. pneumoniae, which poses a significant threat to antibacterial treatment efficacy and public health. Outer membrane vesicles (OMVs) have been identified as carriers capable of facilitating the transfer of virulence and resistance genes. However, the role of OMVs in carbapenem-resistant K. pneumoniae under external pressures such as antibiotic and phage treatments remains unclear.MethodsTo isolate and purify OMVs under the pressure of phages and tigecycline, we subjected K. pneumoniae 0692 harboring plasmid-mediated blaNDM-1 and blaKPC-2 genes to density gradient separation. The double-layer plate method was used to isolate MJ1, which efficiently lysed K. pneumoniae 0692 cells. Transmission electron microscopy (TEM) was used to characterize the isolated phages and extract OMV groups for relevant morphological identification. Determination of protein content of each OMV group was conducted through bicinchoninic acid assay (BCA) and proteomic analysis.ResultsK. pneumoniae 0692 released OMVs in response to different environmental stimuli, which were characterized through TEM as having the typical structure and particle size of OMVs. Phage or tigecycline treatment alone resulted in a slight increase in the mean protein concentration of OMVs secreted by K. pneumoniae 0692 compared to that in the untreated group. However, when phage treatment was combined with tigecycline, there was a significant reduction in the average protein concentration of OMVs compared to tigecycline treatment alone. Proteomics showed that OMVs encapsulated numerous functional proteins and that under different external stresses of phages and tigecycline, the proteins carried by K. pneumoniae 0692-derived OMVs were significantly upregulated or downregulated compared with those in the untreated group.ConclusionsThis study confirmed the ability of OMVs to carry abundant proteins and highlighted the important role of OMV-associated proteins in bacterial responses to phages and tigecycline, representing an important advancement in microbial resistance research.