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1.
Carbohydr Polym ; 332: 121889, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38431406

RESUMO

Metabolic alterations within mitochondria, encompassing processes such as autophagy and energy metabolism, play a pivotal role in facilitating the swift proliferation, invasion, and metastasis of cancer cells. Despite this, there is a scarcity of currently available medications with proven anticancer efficacy through the modulation of mitochondrial dysfunction in a clinical setting. Here, we introduce the structural characteristics of RN0D, a galactoglucan isolated and purified from Panax notoginseng flowers, mainly composed of ß-1,4-galactan and ß-1,3/1,6-glucan. RN0D demonstrates the capacity to induce mitochondrial impairment in cancer cells, leading to the accumulation of reactive oxygen species, initiation of mitophagy, and reduction in both mitochondrial number and size. This sequence of events ultimately results in the inhibition of mitochondrial and glycolytic bioenergetics, culminating in the demise of cancer cells due to adenosine triphosphate (ATP) deprivation. Notably, the observed bioactivity is attributed to RN0D's direct targeting of Galectin-3, as affirmed by surface plasmon resonance studies. Furthermore, RN0D is identified as an activator of the PTEN-induced kinase 1 (PINK1)/Parkin pathway, ultimately instigating cytotoxic mitophagy in tumor cells. This comprehensive study substantiates the rationale for advancing RN0D as a potentially efficacious anticancer therapeutic.


Assuntos
Neoplasias , Panax notoginseng , Polissacarídeos Bacterianos , Humanos , Mitofagia , Galactanos , Glucanos , Morte Celular , Ubiquitina-Proteína Ligases/metabolismo , Proteínas Quinases/metabolismo
2.
Carbohydr Res ; 537: 109056, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38377833

RESUMO

Exopolysaccharides (EPSs) were isolated and purified from Lacticaseibacillus casei strains type V and RW-3703M grown under various fermentation conditions (carbon source, incubation temperature, and duration). Identical 1H NMR spectra were obtained in all cases. The molar mass determined by size-exclusion chromatography coupled with multi-angle light scattering was different for the two strains and in different culture media. The primary structure was elucidated using chemical and spectroscopic techniques. Monosaccharide and absolute configuration analyses gave the following composition: d-Glc, 1; d-Gal, 2; l-Rha, 2; d-GlcNAc, 1. Methylation analysis indicated the presence of 4-linked Glc, terminal and 6-linked Gal, terminal and 3-linked Rha, and 3,4,6-linked GlcNAc. On the basis of one- and two-dimensional 1H and 13C NMR data, the structure of the EPS was consistent with the following hexasaccharide repeating unit: {4)[Rhap(α1-3)][Galp(α1-6)]GlcpNAc(ß1-6)Galp(α1-3)Rhap(ß1-4)Glcp(ß1-}n. Complete 1H and 13C NMR assignments are reported.


Assuntos
Polissacarídeos Bacterianos , Sequência de Carboidratos , Polissacarídeos Bacterianos/química , Espectroscopia de Ressonância Magnética
3.
Appl Microbiol Biotechnol ; 108(1): 227, 2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38381223

RESUMO

The extracellular heteropolysaccharide xanthan, synthesized by bacteria of the genus Xanthomonas, is widely used as a thickening and stabilizing agent across the food, cosmetic, and pharmaceutical sectors. Expanding the scope of its application, current efforts target the use of xanthan to develop innovative functional materials and products, such as edible films, eco-friendly oil surfactants, and biocompatible composites for tissue engineering. Xanthan-derived oligosaccharides are useful as nutritional supplements and plant defense elicitors. Development and processing of such new functional materials and products often necessitate tuning of xanthan properties through targeted structural modification. This task can be effectively carried out with the help of xanthan-specific enzymes. However, the complex molecular structure and intricate conformational behavior of xanthan create problems with its enzymatic hydrolysis or modification. This review summarizes and analyzes data concerning xanthan-degrading enzymes originating from microorganisms and microbial consortia, with a particular focus on the dependence of enzymatic activity on the structure and conformation of xanthan. Through a comparative study of xanthan-degrading pathways found within various bacterial classes, different microbial enzyme systems for xanthan utilization have been identified. The characterization of these new enzymes opens new perspectives for modifying xanthan structure and developing innovative xanthan-based applications. KEY POINTS: • The structure and conformation of xanthan affect enzymatic degradation. • Microorganisms use diverse multienzyme systems for xanthan degradation. • Xanthan-specific enzymes can be used to develop xanthan variants for novel applications.


Assuntos
Suplementos Nutricionais , Consórcios Microbianos , Polissacarídeos Bacterianos , Hidrólise , Mutagênese Sítio-Dirigida
4.
Molecules ; 29(4)2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38398526

RESUMO

The blue crab (BC) Portunus segnis is considered an invasive species colonizing Tunisian coasts since 2014. This work aims to explore its associated bacteria potential to produce anionic exopolysaccharides (EPSs) in order to open up new ways of valorization. In this study, different BC samples were collected from the coastal area of Sfax, Tunisia. First, bacterial DNA was extracted from seven different fractions (flesh, gills, viscera, carapace scraping water, and three wastewaters from the production plant) and then sequenced using the metabarcoding approach targeting the V3-V4 region of the 16S rDNA to describe their microbiota composition. Metabarcoding data showed that the dominant bacterial genera were mainly Psychrobacter, Vagococcus, and Vibrio. In parallel, plate counting assays were performed on different culture media, and about 250 bacterial strains were isolated and identified by sequencing the 16S rDNA. EPS production by this new bacterial diversity was assessed to identify new compounds of biotechnological interest. The identification of the bacterial strains in the collection confirmed the dominance of Psychrobacter spp. strains. Among them, 43 were identified as EPS producers, as revealed by Stains-all dye in agarose gel electrophoresis. A Buttiauxella strain produced an EPS rich in both neutral sugars including rare sugars such as rhamnose and fucose and uronic acids. This original composition allows us to assume its potential for biotechnological applications and, more particularly, for developing innovative therapeutics. This study highlights bacterial strains associated with BC; they are a new untapped source for discovering innovative bioactive compounds for health and cosmetic applications, such as anionic EPS.


Assuntos
Braquiúros , Microbiota , Animais , Braquiúros/genética , Bactérias , Açúcares , DNA Ribossômico/genética , Polissacarídeos Bacterianos
5.
Plant Foods Hum Nutr ; 79(1): 189-193, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38315314

RESUMO

Due to the limitations of the properties of chestnut flour, its applications have been restricted. The objective of this study is to investigate the impact of whey protein isolate (WPI) and xanthan gum (XG) on the functional and digestive properties of chestnut flour, specifically focusing on gel texture, solubility and swelling power, water absorption capacity, freeze-thaw stability and starch digestibility. The addition of both WPI and XG reduced the gel hardness, gumminess and chewiness of the co-gelatinized and physically mixed samples. Furthermore, the inclusion of physically mixed WPI and XG led to an increase in the solubility (from 58.2 to 75.0%) and water absorption capacity (from 3.11 to 5.45 g/g) of chestnut flour. The swelling power of the chestnut flour was inhibited by both additives. WPI was superior to XG at maintaining freeze-thaw stability, by reducing the syneresis from 71.9 to 68.1%. Additionally, WPI and XG contributed to the inhibition of starch hydrolysis in the early stage of digestion, resulting in a lower starch digestibility of chestnut flours. This research provides insights into the interaction mechanisms between WPI, XG, and chestnut flour, offering valuable information for the development of chestnut flour products with enhanced properties.


Assuntos
Farinha , Polissacarídeos Bacterianos , Amido , Proteínas do Soro do Leite , Água
6.
Langmuir ; 40(9): 4860-4870, 2024 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-38394629

RESUMO

Tildipirosin has no significant inhibitory effect on intracellular bacteria because of its poor membrane permeability. To this end, tildipirosin-loaded xanthan gum-gelatin composite nanogels were innovatively prepared to improve the cellular uptake efficiency. The formation of the nanogels via interactions between the positively charged gelatin and the negatively charged xanthan gum was confirmed by powder X-ray diffraction and Fourier transform infrared. The results indicate that the optimal tildipirosin composite nanogels possessed a 3D network structure and were shaped like a uniformly dispersed ellipse, and the particle size, PDI, and ζ potential were 229.4 ± 1.5 nm, 0.26 ± 0.04, and -33.2 ± 2.2 mV, respectively. Interestingly, the nanogels exhibited gelatinase-responsive characteristics, robust cellular uptake via clathrin-mediated endocytosis, and excellent sustained release. With those pharmaceutical properties provided by xanthan gum-gelatin composite nanogels, the anti-Staphylococcus aureus activity of tildipirosin was remarkably amplified. Further, tildipirosin composite nanogels demonstrated good biocompatibility and low in vivo and in vitro toxicities. Therefore, we concluded that tildipirosin-loaded xanthan gum-gelatin composite nanogels might be employed as a potentially effective gelatinase-responsive drug delivery for intracellular bacterial infection.


Assuntos
Gelatina , Gelatinases , Polissacarídeos Bacterianos , Tilosina/análogos & derivados , Nanogéis , Gelatina/química
7.
Biochemistry ; 63(5): 699-710, 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38386885

RESUMO

Campylobacter jejuni is a Gram-negative pathogenic bacterium commonly found in chickens and is the leading cause of human diarrheal disease worldwide. The various serotypes of C. jejuni produce structurally distinct capsular polysaccharides (CPSs) on the exterior surfaces of the cell wall. The capsular polysaccharide from C. jejuni serotype HS:5 is composed of a repeating sequence of d-glycero-d-manno-heptose and d-glucitol-6-phosphate. We previously defined the pathway for the production of d-glycero-d-manno-heptose in C. jejuni. Here, we elucidate the biosynthetic pathway for the assembly of cytidine diphosphate (CDP)-6-d-glucitol by the combined action of two previously uncharacterized enzymes. The first enzyme catalyzes the formation of CDP-6-d-fructose from cytidine triphosphate (CTP) and d-fructose-6-phosphate. The second enzyme reduces CDP-6-d-fructose with NADPH to generate CDP-6-d-glucitol. Using sequence similarity network (SSN) and genome neighborhood network (GNN) analyses, we predict that these pairs of proteins are responsible for the biosynthesis of CDP-6-d-glucitol and/or CDP-d-mannitol in the lipopolysaccharides (LPSs) and capsular polysaccharides in more than 200 other organisms. In addition, high resolution X-ray structures of the second enzyme are reported, which provide novel insight into the manner in which an open-chain nucleotide-linked sugar is harbored in an active site cleft.


Assuntos
Campylobacter jejuni , Animais , Humanos , Sorbitol/metabolismo , Galinhas/metabolismo , Polissacarídeos/metabolismo , Cistina Difosfato/metabolismo , Frutose/metabolismo , Polissacarídeos Bacterianos/metabolismo
8.
Int J Biol Macromol ; 261(Pt 2): 129855, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38302013

RESUMO

Environmentally friendly emulsifiers safe for human consumption are urgently needed to stabilize emulsions for applications in the food industry. In this study, we prepared complexes combining modified aggregated insoluble soybean protein hydrolysate (AISPH) mixed with xanthan gum (XG) (0.05-0.3 %, w/v), and further to construct water-in-oil-in-water (W/O/W) emulsions to deliver vitamin C and ß-carotene. We observed a decrease in the AISPH α-helix and ß-sheet content, surface hydrophobicity, and fluorescence intensity all decreased after binding. In contrast, the particle size and absolute ξ-potential significantly increased, indicating that molecular non-covalent interactions occurred in the solution. The emulsification property of AISPH was also improved by adding XG, and the AISPH-XG-stabilized emulsion showed improved stability, encapsulation efficiency, and rheological properties. Among them, AISPH-XG-0.25-stabilized emulsion exhibited a smaller particle size (8.41 ± 0.49 µm) and the highest encapsulation efficiency for vitamin C (90.03 ± 0.23 %) and ß-carotene (70.56 ± 0.06 %). Additionally, simulated gastric digestion indicated that vitamin C and ß-carotene bioavailability increased by 3.6 and 5.8 times, respectively. Finally, the emulsion exhibited good pH, ionic, and thermal stability. In general, AISPH-XG-stabilized W/O/W emulsions showed good stability and carrying capacity, providing a theoretical basis for improving their application.


Assuntos
Polissacarídeos Bacterianos , beta Caroteno , Humanos , Emulsões/química , Hidrolisados de Proteína , Ácido Ascórbico , Vitaminas , Água/química
9.
ACS Biomater Sci Eng ; 10(3): 1661-1675, 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38364815

RESUMO

Intra-articular trauma typically initiates the overgeneration of reactive oxidative species (ROS), leading to post-traumatic osteoarthritis and cartilage degeneration. Xanthan gum (XG), a branched polysaccharide, has shown its potential in many biomedical fields, but some of its inherent properties, including undesirable viscosity and poor mechanical stability, limit its application in 3D printed scaffolds for cartilage regeneration. In this project, we developed 3D bioprinted XG hydrogels by modifying XG with methacrylic (MA) groups for post-traumatic cartilage therapy. Our results demonstrated that the chemical modification optimized the viscoelasticity of the bioink, improved printability, and enhanced the mechanical properties of the resulting scaffolds. The XG hydrogels also exhibit decent ROS scavenging capacities to protect stem cells from oxidative stress. Furthermore, XGMA(H) (5% MA substitution) exhibited superior chondrogenic potential in vitro and promoted cartilage regeneration in vivo. These dual-functional XGMA hydrogels may provide a new opportunity for cartilage tissue engineering.


Assuntos
Antioxidantes , Hidrogéis , Polissacarídeos Bacterianos , Hidrogéis/farmacologia , Hidrogéis/uso terapêutico , Hidrogéis/química , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Tecidos Suporte/química , Espécies Reativas de Oxigênio , Cartilagem , Regeneração
10.
J Pharm Biomed Anal ; 241: 115995, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38309096

RESUMO

Polysaccharide-based vaccines cannot stimulate long-lasting immune response in infants due to their inability to elicit a T-cell-dependent immune response. This has been addressed using conjugation technology, where conjugates were produced by coupling a carrier protein to polysaccharides using different conjugation chemistries, such as cyanylation, reductive amination, ethylene diamine reaction, and others. Many glycoconjugate vaccines that are manufactured using different conjugation technologies are already in the market for neonates, infants and young children (e.g., Haemophilus influenzae type-b, Streptococcus pneumoniae and Neisseria meningitidis vaccines), and all of them elicit a T-cell dependent immune response. To manufacture glycoconjugate vaccines, the capsular polysaccharide is first activated by converting its hydroxyl groups to aldehyde-, cyanyl-, or cyanate ester groups, depending on the conjugation chemistry selected. The oxidized and reduced aldehyde functional groups of the polysaccharides are subsequently reacted with the amino groups of carrier protein by reductive amination to form a stable amide bond. In CDAP-based conjugation, the polysaccharide -OH groups are activated to form cyanyl-, or cyanate ester groups to react with the amino groups of carrier protein and forms an isourea bond. Understanding the extent of polysaccharide activation/modification is essential since it directly influences the molar mass of the conjugate, its stability, and the immunogenicity of the product. Reported methods are available to estimate the aldehyde groups of polysaccharides generated by reductive amination. However, no method is available to quantify the cyanyl or cyanate ester (-OCN) groups generated by cyanylation with 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP). We report a novel strategy using an O-phthalaldehyde (OPA) derivatization process followed by size-exclusion chromatography (SEC) high-performance liquid chromatography (HPLC) separation and UV detection. The cyanate ester groups on the activated polysaccharide directly reveal the extent of polysaccharide activation/modification and the residual activated groups in the purified conjugates. This method would be useful for conjugate vaccine manufacturing using CDAP chemistry.


Assuntos
Polissacarídeos Bacterianos , o-Ftalaldeído , Lactente , Criança , Recém-Nascido , Humanos , Pré-Escolar , Vacinas Conjugadas/química , Proteínas de Transporte , Glicoconjugados , Cianatos , Ésteres , Anticorpos Antibacterianos
11.
Carbohydr Res ; 536: 109058, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38354653

RESUMO

Campylobacters are important causes of gastrointestinal illness and the capsular polysaccharides (CPS) they produce are key virulence factors and targets for vaccine development. We report here the synthesis of two fragments of the Campylobacter jejuni CG8486 strain CPS that contain a rare 6-deoxy-d-ido-heptopyranose residue and, in one target, two O-methyl phosphoramidate (MeOPN) motifs. The synthetic approach features the stereoselective construction of the ß-d-ido-heptopyranoside linkage via glycosylation with a ß-d-galacto-heptopyranoside donor followed by a one-pot sequential C-2 and C-3 inversion. During the syntheses, we uncovered a number of interesting conformational effects with regard to the 6-deoxy-ido-heptopyranose ring, the glycosidic linkage connecting the two monosaccharides, and the MeOPN groups.


Assuntos
Campylobacter jejuni , Polissacarídeos Bacterianos , Polissacarídeos Bacterianos/química , Campylobacter jejuni/química , Campylobacter jejuni/metabolismo , Monossacarídeos , Glicosilação
12.
Carbohydr Polym ; 330: 121848, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38368118

RESUMO

The capsular polysaccharides (CPS) of Group B Streptococcus play a crucial role as virulence determinants and are potential candidates for antigenic components in vaccine formulations. Alkaline treatments are commonly used to extract polysaccharides owing to their efficiency and cost-effectiveness; however, they may induce the removal of N-acetyl groups from CPS. This study involved re-N-acetylation of CPS Ia to improve its biological functionality. The structural modifications and enhanced antigenicity of CPS Ia were observed after re-N-acetylation. The tetanus toxoid (TT) was conjugated with either partially de-N-acetylated or fully re-N-acetylated CPS. As a result, the conjugate containing re-N-acetylated CPS (IaReN-TT) enhanced the induction of IgG antibody levels and functional antibodies in mice. Both passive and active protection assays substantiated the superior protective efficacy of IaReN-TT, suggesting that the re-N-acetylation of CPS Ia could be a critical step in refining the immunogenic profile of glycoconjugate vaccines.


Assuntos
Polissacarídeos Bacterianos , Toxoide Tetânico , Animais , Camundongos , Vacinas Conjugadas , Acetilação , Glicoconjugados , Streptococcus
13.
Molecules ; 29(3)2024 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-38338439

RESUMO

The literature presents the preserving effect of biological coatings developed from various microbial sources. However, the presented work exhibits its uniqueness in the utilization of halophilic exopolysaccharides as food coating material. Moreover, such extremophilic exopolysaccharides are more stable and economical production is possible. Consequently, the aim of the presented research was to develop a coating material from marine exopolysaccharide (EPS). The significant EPS producers having antagonistic attributes against selected phytopathogens were screened from different marine water and soil samples. TSIS01 isolate revealed the maximum antagonism well and EPS production was selected further and characterized as Bacillus tequilensis MS01 by 16S rRNA analysis. EPS production was optimized and deproteinized EPS was assessed for biophysical properties. High performance thin layer chromatography (HPTLC) analysis revealed that EPS was a heteropolymer of glucose, galactose, mannose, and glucuronic acid. Fourier transform infrared spectroscopy, X-ray diffraction, and UV-visible spectra validated the presence of determined sugars. It showed high stability at a wide range of temperatures, pH and incubation time, ≈1.63 × 106 Da molecular weight, intermediate solubility index (48.2 ± 3.12%), low water holding capacity (12.4 ± 1.93%), and pseudoplastic rheologic shear-thinning comparable to xanthan gum. It revealed antimicrobial potential against human pathogens and antioxidants as well as anti-inflammatory potential. The biocontrol assay of EPS against phytopathogens revealed the highest activity against Alternaria solani. The EPS-coated and control tomato fruits were treated with A. solani suspension to check the % disease incidence, which revealed a significant (p < 0.001) decline compared to uncoated controls. Moreover, it revealed shelf-life prolonging action on tomatoes comparable to xanthan gum and higher than chitosan. Consequently, the presented marine EPS was elucidated as a potent coating material to mitigate post-harvest losses.


Assuntos
Glucose , Polissacarídeos Bacterianos , Humanos , RNA Ribossômico 16S/genética , Polissacarídeos Bacterianos/química , Antioxidantes/farmacologia , Antioxidantes/química , Açúcares , Água/química , Espectroscopia de Infravermelho com Transformada de Fourier
14.
Colloids Surf B Biointerfaces ; 236: 113830, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38422667

RESUMO

Novel colorimetric films based on gellan gum (GG) containing red cabbage anthocyanins extract (RCAE) were prepared as pH-freshness smart labels for real-time visual detection of mushroom freshness. The GG/RCAE films had excellent pH and ammonia sensitivity. The GG/RCAE-0.2-0.3 films had the highest sensitivity to acetic acid. The SEM micrographs, AFM images, FT-IR and XRD spectra demonstrated that RCAE were successfully combined into the film-forming substrate. The incorporation of RCAE resulted in the increase of thermal stability, opacity and surface hydrophobicity of films. Meanwhile, the GG/RCAE-0.2 film exhibited stronger tensile strength and excellent color stability at 4℃. The color changes of GG/RCAE-0.2 film were visually easier to distinguish during the storage of mushroom. The results showed the GG/RCAE films could be used as pH-freshness smart labels to detect the freshness of fruits and vegetables.


Assuntos
Agaricales , Brassica , Polissacarídeos Bacterianos , Antocianinas , Espectroscopia de Infravermelho com Transformada de Fourier , Concentração de Íons de Hidrogênio , Embalagem de Alimentos
15.
Int J Biol Macromol ; 262(Pt 1): 129952, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38320635

RESUMO

Yoghurt fermented by Leuconostoc mesenteroides XR1 from Kefir grains was found to produce a unique silk drawing phenomenon. This property was found to be associated with the exopolysaccharides (EPS), X-EPS, produced by strain XR1. In order to better understand the mechanism that produced this phenomenon, the X-EPS was extracted, purified and characterized. The molecular weight and monosaccharide composition were determined by size exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS) and ion chromatography (IC) analysis, respectively. The results showed that its molecular weight was 4.183 × 106 g/mol and its monosaccharide composition was glucose, and glucuronic acid, with the contents of 567.6148 and 0.2096 µg/mg, respectively. FT-IR and NMR analyses showed that X-EPS was an α-pyranose polysaccharide and was composed of 92.22 % α-(1 â†’ 6) linked d-glucopyranose units and 7.77 % α-(1 â†’ 3) branching. Furthermore, it showed a chain-like microstructure with branches in atomic force microscopy (AFM) and scanning electron microscopy (SEM) experiments. These results suggested that the unique structure of X-EPS, gave the yoghurt a strong viscosity and cohesiveness, which resulted in the silk drawing phenomenon. This work suggested that X-EPS holds the potential for food and industrial applications.


Assuntos
Leuconostoc mesenteroides , Leuconostoc/química , Iogurte , Espectroscopia de Infravermelho com Transformada de Fourier , Polissacarídeos Bacterianos/química , Monossacarídeos
16.
Int J Biol Macromol ; 262(Pt 1): 130006, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38331067

RESUMO

The processing characteristics of yogurt are closely related to the composition and arrangement of exopolysaccharides (EPS) in lactic acid bacteria (LAB). To fully understand and develop the functional properties of EPS and to study the effect of EPS molecular weight on yogurt and its mechanism, the physicochemical properties of high molecular weight EPS-LH43, medium molecular weight EPS-LH13, and low molecular weight EPS-LH23, as well as the gel properties and protein conformation of yogurt, were determined and analyzed in this experiment. The results indicate that EPS-LH43 and EPS-LH13 are both composed of mannose, rhamnose, galacturonic acid, glucose, and galactose. EPS-LH23 is composed of mannose, galacturonic acid, glucose, and galactose. Their Number-average Molecular Weight is 5.21 × 106 Da, 2.39 × 106 Da and 3.76 × 105 Da, respectively. In addition, all three types of EPS have good thermal stability and can improve the stability of casein. In addition, the analysis of the texture, particle size, potential, water holding capacity, rheology, low field nuclear magnetic resonance, microstructure, and flavor characteristics of yogurt confirmed the relationship between the molecular weight of LAB EPS and the gel properties of yogurt. Fluorescence spectrophotometer and circular dichroism analysis indicate that the different molecular weights of LAB EPS have different effects on protein structure, which is an intrinsic factor leading to significant differences in the gel properties of the three types of fermented milk. These findings provide new references for enhancing the understanding of the structure-activity relationship of EPS and indicate that EPS-LH43 can be used to improve the gel properties of dairy products.


Assuntos
Ácidos Hexurônicos , Lactobacillus helveticus , Iogurte , Iogurte/microbiologia , Polissacarídeos Bacterianos/química , Peso Molecular , Galactose/análise , Manose , Glucose/análise , Fermentação
17.
Int J Biol Macromol ; 262(Pt 1): 130045, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38336317

RESUMO

The K239 type capsular polysaccharide (CPS) isolated from Acinetobacter baumannii isolate MAR19-4435 was studied by sugar analysis, one- and two-dimensional 1H and 13C NMR spectroscopy. K239 consists of branched heptasaccharide repeats (K-units) comprised of five residues of l-rhamnose (l-Rhap), and one residue each of d-glucuronic acid (d-GlcpA) and N-acetyl-d-glucosamine (d-GlcpNAc). The structure of K239 is closely related to that of the A. baumannii K86 CPS type, though the two differ in the 2,3-substitution patterns on the l-Rhap residue that is involved in the linkage between K-units in the CPS polymer. This structural difference was attributed to the presence of a gtr221 glycosyltransferase gene and a wzyKL239 polymerase gene in KL239 that replaces the gtr80 and wzyKL86 genes in the KL86 CPS biosynthesis gene cluster. Comparison of the two structures established the role of a novel WzyKL239 polymerase encoded by KL239 that forms the ß-d-GlcpNAc-(1→2)-l-Rhap linkage between K239 units. A. baumannii MAR19-4435 was found to be non-susceptible to infection by the APK86 bacteriophage, which encodes a depolymerase that specifically cleaves the linkage between K-units in the K86 CPS, indicating that the difference in 2,3-substitution of l-Rhap influences the susceptibility of this isolate to bacteriophage activity.


Assuntos
Acinetobacter baumannii , Polissacarídeos Bacterianos , Polissacarídeos Bacterianos/química , Acinetobacter baumannii/genética , Acinetobacter baumannii/química , Cápsulas Bacterianas/química , Nucleotidiltransferases/genética , Família Multigênica
18.
Microb Biotechnol ; 17(2): e14394, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38226955

RESUMO

Corn straw is an abundant and renewable alternative for microbial biopolymer production. In this paper, an engineered Sphingomonas sanxanigenens NXG-P916 capable of co-utilising glucose and xylose from corn straw total hydrolysate to produce xanthan gum was constructed. This strain was obtained by introducing the xanthan gum synthetic operon gum as a module into the genome of the constructed chassis strain NXdPE that could mass produce activated precursors of polysaccharide, and in which the transcriptional levels of gum genes were optimised by screening for a more appropriate promoter, P916 . As a result, strain NXG-P916 produced 9.48 ± 0.34 g of xanthan gum per kg of fermentation broth (g/kg) when glucose was used as a carbon source, which was 2.1 times improved over the original engineering strain NXdPE::gum. Furthermore, in batch fermentation, 12.72 ± 0.75 g/kg xanthan gum was produced from the corn straw total hydrolysate containing both glucose and xylose, and the producing xanthan gum showed an ultrahigh molecular weight (UHMW) of 6.04 × 107 Da, which was increased by 15.8 times. Therefore, the great potential of producing UHMW xanthan gum by Sphingomonas sanxanigenens was proved, and the chassis NXdPE has the prospect of becoming an attractive platform organism producing polysaccharides derived from biomass hydrolysates.


Assuntos
Glucose , Polissacarídeos Bacterianos , Sphingomonas , Xilose , Sphingomonas/genética , Zea mays , Peso Molecular
19.
Chemistry ; 30(12): e202303753, 2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38215247

RESUMO

The enzyme-resistant thioglycosides are highly valuable immunogens because of their enhanced metabolic stability. We report the first synthesis of a family of thiooligosaccharides related to the capsular polysaccharides (CPS) of Campylobacter jejuni HS:4 for potential use in conjugate vaccines. The native CPS structures of the pathogen consist of a challenging repeating disaccharide formed with ß(1→4)-linked 6-deoxy-ß-D-ido-heptopyranoside and N-acetyl-D-glucosamine; the rare 6-deoxy-ido-heptopyranosyl backbone and ß-anomeric configuration of the former monosaccharide makes the synthesis of this family of antigens very challenging. So far, no synthesis of the thioanalogs of the CPS antigens have been reported. The unprecedented synthesis presented in this work is built on an elegant approach by using ß-glycosylthiolate as a glycosyl donor to open the 2,3-epoxide functionality of pre-designed 6-deoxy-ß-D-talo-heptopyranosides. Our results illustrated that this key trans-thioglycosylation can be designed in a modular and regio and stereo-selective manner. Built on the success of this novel approach, we succeeded the synthesis of a family of thiooligosaccharides including a thiohexasaccharide which is considered to be the desired antigen length and complexity for immunizations. We also report the first direct conversion of base-stable but acid-labile 2-trimethylsilylethyl glycosides to glycosyl-1-thioacetates in a one-pot manner.


Assuntos
Campylobacter jejuni , Polissacarídeos , Polissacarídeos/química , Oligossacarídeos , Dissacarídeos , Polissacarídeos Bacterianos/química
20.
Int J Biol Macromol ; 260(Pt 2): 129610, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38246463

RESUMO

The aim of this work was to determine rheological and disperse characteristics and stability of oil-in-water emulsions stabilized by soy protein isolate (SPI) and xanthan gum (XG), as natural components. The effects of their combination on emulsion stabilization have not been investigated yet. The existence of interactions between the two macromolecules were indicated by the influence of XG on SPI surface hydrophobicity and surface tension values. Increase in SPI concentration from 1 to 3 % shift of distribution curves towards smaller particle size, while the opposite effects of further increase of SPI was obtained. The emulsions stabilized by SPI showed shear-thinning flow behavior, which changed to thixotropic at 5 % of SPI concentration. The presence of XG in emulsions at low concentrations did not affect the size distribution of the droplets, while at 0.1 % of XG Sauter mean diameter value raised and distribution curves were shifted towards a higher particle size. The presence of XG at higher concentration resulted in thixotropic flow behavior of emulsions. Also, increase in XG concentration led to the increase in consistency index and extent of non-Newtonian behavior of emulsions and enhanced the influence of the elastic modulus and creaming stability of the systems.


Assuntos
Proteínas de Soja , Água , Emulsões/química , Proteínas de Soja/química , Água/química , Polissacarídeos Bacterianos/química
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