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1.
Food Chem ; 371: 131114, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34638013

RESUMO

This study aimed to examine the gelation and microstructural properties of scallop male gonad hydrolysates (SMGHs) in the presence of low-acyl gellan gum (GG) at different mass ratios. The rheological results showed that both elastic modulus and thermal stability of SMGHs were significantly improved by the addition of GG. Meanwhile, the relaxation time T23 was significantly reduced in SMGHs/GG by low-field nuclear magnetic resonance, indicating a strong interaction between SMGHs and GG. Fourier transform infrared spectroscopy indicated the blueshift of amide I and II peaks in SMGHs/GG further demonstrated the electrostatic interaction between SMGHs and GG. The network structure of SMGHs/GG binary complexes was more compact and the surface was smoother than that of SMGHs by cryo-scanning electron microscopy. Furthermore, increasing the content of GG in the SMGHs/GG binary complex significantly reinforced the gel strength and promoted the gelation process.


Assuntos
Pectinidae , Hidrolisados de Proteína , Animais , Gônadas , Masculino , Polissacarídeos Bacterianos
2.
J Sci Food Agric ; 102(2): 862-867, 2022 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-34173230

RESUMO

BACKGROUND: As a natural food additive, exopolysaccharide (EPS) produced by Streptococcus thermophilus can improve product viscosity and texture. The protein EpsA is a putative pathway-specific transcriptional regulator for EPS biosynthesis in S. thermophilus. RESULTS: According to comparative analysis of EPS biosynthetic gene clusters, a conserved region of epsA (609 bp) was employed to design primer pair epsA-F/R as a molecular marker for the isolation of EPS-producing (EPS+ ) S. thermophilus. Two EPS+ S. thermophiles strains, AR333 and S-3, were band-positive, whereas Lactococcus lactis NZ9000 (non-EPS-producing, EPS- ), Lactobacillus casei LC2W (EPS+ ) and L. plantarum AR113 (EPS+ ) were negative by polymerase chain reaction (PCR) amplicon bands using the epsA probe. This indicated good specificity of the epsA probe to EPS+ S. thermophilus. Moreover, based on PCR screening with the epsA probe, 23 positive strains were isolated and identified as S. thermophilus from our microbial library and natural fermented milk with 141.3-309.2 mg L-1 of EPS production, demonstrating the validity of our molecular marker screening method. CONCLUSION: The designed molecular marker of epsA can rapidly screen EPS+ S. thermophilus, which has potential application in the dairy and other food industries. © 2021 Society of Chemical Industry.


Assuntos
Polissacarídeos Bacterianos/biossíntese , Streptococcus thermophilus/genética , Streptococcus thermophilus/isolamento & purificação , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Bovinos , Produtos Fermentados do Leite/microbiologia , Fermentação , Marcadores Genéticos , Família Multigênica , Streptococcus thermophilus/metabolismo
3.
Food Chem ; 367: 130738, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34384978

RESUMO

A homogeneous galactoglucan was purified from the alkali-extracted polysaccharides from the basidioma of Macrolepiota albuminosa by gradient ethanol precipitation, whose proposed structure was given for the first time. Results showed it had a molecular weight of 210 kDa, and mainly consisted of glucose and galactose. There were abundant filaments, randomly distributed sheet-like and flaky appearance in its surface by SEM observation. Its backbone comprised ß-(1 â†’ 6)-Glcp, α-(1 â†’ 6)-Galp and ß-(1 â†’ 3,6)-Glcp residues at 4:1:1, terminated by ß-(1 â†’ 3)-Glcp and T-Glcp residues. Rheological measurements suggested its steady flow behavior was highly dependent on concentrations. Newtonian behavior was evident at low concentrations, whereas pseudoplastic behavior was observed at high concentrations. Besides, the X-ray diffraction patterns proved the presence of amorphous structure. The conformational parameters were detected by HPSEC-MALLS-RI, revealing a random coil conformation in NaNO3 aqueous solution. This work provides a theoretical basis for the application of polysaccharides from M. albuminosa in food- and drug-based therapies.


Assuntos
Galactanos , Polissacarídeos Bacterianos , Glucanos , Peso Molecular , Polissacarídeos
4.
Food Microbiol ; 102: 103924, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34809950

RESUMO

Exopolysaccharides production by 3 ropy strains of Lactobacillus delbrueckii subsp. bulgaricus of dairy origin was evaluated in synthetic medium by combining different approaches: impedometric measurements, fluorescent microscopy and flow cytometry analyses. The evaluation of ΔE by impedometric measurement (E%max-E%40h) allowed the detection of EPS production in synthetic medium, but the differences in EPS production kinetic was highlighted by flow cytometry analysis and fluorescent microcopy. This approach enabled us to unravel the diversity in EPS synthesis and release into the laboratory medium during the growth of the strains. Our results showed that the maximum EPS production occurred after 8 h of incubation, when cells were in late exponential growth phase. Furthermore, flow cytometry analysis revealed that only part of the cell population could be identified as EPS producer or as EPS-bounded cell. Therefore, the combined approach used, allowed us to define at the same time the kinetics of EPS production and release by three strains belonging to the same species and, highlight that the production of EPS depends also on the number of EPS-producing cells within the same population. This approach could be useful for the selection of strains to be used as starter cultures in dairy products where EPS production is considered an important feature.


Assuntos
Lactobacillus delbrueckii , Polissacarídeos Bacterianos/biossíntese , Meios de Cultura , Laticínios/microbiologia , Fermentação , Lactobacillus delbrueckii/classificação , Lactobacillus delbrueckii/metabolismo
5.
Biomacromolecules ; 22(11): 4535-4543, 2021 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-34609837

RESUMO

We report on the production of a flame-resistant xanthan gum (XG)-based hydrogel formulation, which could be directly applied onto the skin for protection against burning projectiles. The hydrogel cream represents an efficient use of XG and starch, both of which are biodegradable, reusable natural materials and are also GRAS-certified. The flame-retardant agent resorcinol bis(diphenyl phosphate) (RDP) was shown to be nontoxic to cells in vitro when adsorbed directly onto the starch delivery vehicle. Three hydrogel formulations were studied, the pure XG hydrogel, commercial FireIce hydrogel, and RDP-XG/RDP-starch hydrogel. After application of a direct flame for 150 s, the RDP-XG/RDP-starch hydrogel produced a thick char layer, which was easily removed, showing undamaged chicken skin and tissue underneath. In contrast, complete burning of skin and tissue was observed on untreated control samples and those covered with FireIce and pure XG hydrogels. The thermal protective performance test was also performed, where the heat transfer was measured as a function of time for all three hydrogels. The RDP-XG/RDP-starch hydrogel was able to prolong the protection time before obtaining a second-degree burn for 103 s, which is double that for FireIce and triple that for the pure XG hydrogel. The model proposed involves endothermic reactions, producing char and burning "cold", as opposed to simply relying on the adsorbed water in the hydrogel for burn protection.


Assuntos
Retardadores de Chama , Hidrogéis , Compostos de Bifenilo , Fosfatos , Polissacarídeos Bacterianos , Resorcinóis , Amido
6.
Int J Pharm ; 609: 121163, 2021 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-34624448

RESUMO

Fungal infections pose a serious threat to humankind due to the toxicity of conventional antifungal therapy and continuous emerging incidence of multidrug resistance. Essential oils fascinated researchers because of their broad antimicrobial activity and minimal cytotoxicity. However, hydrophobic, volatile and low water solubility of essential oils hinder their applications in pharmaceutical industries. Therefore, in this study we have loaded eucalyptol/ ß-cyclodextrin inclusion complex to gellan/polyvinyl alcohol nanofibers (EPNF) to eradicate Candida albicans and Candida glabrata biofilms. The electrospun nanofibers characterized by various physicochemical techniques and it was observed that EPNF possess highly hydrophilic surface property that facilitate rapid drug release. EPNF inhibited approximately 70% biofilm of C. albicans and C. glabrata. Time kill results depicted that eucalyptol (EPTL) encapsulation in the nanofibers prolonged its antifungal activity than the pure EPTL. Electron microscopy studies revealed that EPNF disrupted the cell surface of Candida. Collectively the current study suggested nanofiber encapsulation enhanced antibiofilm activity of eucalyptol and these nanoscale systems can serve as an alternative therapeutic strategy to treat fungal infections. Further, the developed nanofibrous materials can be applied as cost effective coating agent for biomedical implants.


Assuntos
Nanofibras , beta-Ciclodextrinas , Antifúngicos , Sistemas de Liberação de Medicamentos , Eucaliptol , Polissacarídeos Bacterianos , Álcool de Polivinil
7.
Vaccine ; 39(45): 6644-6652, 2021 10 29.
Artigo em Inglês | MEDLINE | ID: mdl-34642087

RESUMO

Conjugation of carbohydrate antigens with a carrier protein is a clinically proven strategy to overcome the poor immunogenicity of bacterial polysaccharide. In addition to its primary role, which is to help generate a T cell-mediate long-lasting immune response directed against the carbohydrate antigen, the carrier protein in a glycoconjugate vaccine can also play an important role as a protective antigen. Among carrier proteins currently used in licensed conjugate vaccines, non-typeable Haemophilus influenzae protein D has been used as an antigenically active carrier protein. Our previous studies also indicate that some carrier proteins provide B cell epitopes, along with T cell helper epitopes. Herein we investigated the dual role of truncated rotavirus spike protein ΔVP8* as a carrier and a protective antigen. Capsular polysaccharide lipoarabinomannan (LAM), purified from Mycobacterium tuberculosis (M.tb), was chemically conjugated with ΔVP8*. Mouse immunization experiments showed that the resultant conjugates elicited strong and specific immune responses against the polysaccharide antigen, and the responses were comparable to those induced by Diphtheria toxoid (DT)-based conjugates. The conjugate vaccine induced enhanced antibody titers and functional antibodies against ΔVP8* when compared to immunization with the unconjugated ΔVP8*. Thus, these results indicate that ΔVP8* can be a relevant carrier protein for glycoconjugate vaccine and the glycoconjugates consisting of ΔVP8* with LAM are effective bivalent vaccine candidates against rotavirus and tuberculosis.


Assuntos
Vacinas Anti-Haemophilus , Mycobacterium tuberculosis , Rotavirus , Tuberculose , Animais , Anticorpos Antibacterianos , Diarreia , Camundongos , Polissacarídeos Bacterianos , Tuberculose/prevenção & controle , Vacinas Combinadas , Vacinas Conjugadas
8.
J Food Sci ; 86(11): 4840-4850, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34642967

RESUMO

Twenty-four strains were isolated from 50 samples of raw cow's milk originated from different regions of Morocco. After different screening methods, one strain was selected as the highest exopolysaccharide (EPS)-producing isolate and was identified by 16S rDNA sequencing as Lacticaseibacillus rhamnosus P14. Moreover, the EPS-producing ability, bacterial growth, and pH of the medium were monitored. The optimization of culture conditions indicated that the high yield of EPS was 685.14 mg/L obtained at 42°C, with lactose as a carbon source. The characterization study showed that the purified EPS consisted of one main fraction that contained 97.67% of carbohydrates. Furthermore, the EPS was identified as a homogeneous polysaccharide, mainly composed of glucose. These results demonstrated the high EPS production ability of the selected L. rhamnosus P14, representing a promising candidate to improve the textural and sensory properties of fermented food.


Assuntos
Leite , Animais , Fermentação , Lactose , Polissacarídeos Bacterianos
9.
Biomacromolecules ; 22(11): 4691-4700, 2021 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-34669370

RESUMO

Xanthan is an extracellular bacterial polysaccharide. It is manufactured commercially by fermentation of Xanthomonas campestris and used extensively in food and other industries to control the viscosity and texture of various products. Its useful properties stem from its occurrence both as a relatively rigid double-helical polymer and as a branched polymer network presumably crosslinked by the same noncovalent interactions that stabilize the double-helical form. Interconversion of these two forms can be achieved through heating and cooling processes. This paper describes a model for this thermally induced transformation under conditions of very dilute aqueous polymer concentration, where the characteristics of double-helical and crosslinked aggregates can be studied experimentally using light scattering. Because xanthan is a regularly repeating copolymer, there is no requirement for specific registration of the two strands of the duplex structure as is required in naturally occurring nucleic acid double helices. Here, we demonstrate the important role of the resulting xanthan structural degeneracy in dictating the characteristics of the temperature-induced conformational transition.


Assuntos
Polissacarídeos Bacterianos , Fermentação , Polissacarídeos Bacterianos/metabolismo , Temperatura , Viscosidade
10.
Int J Mol Sci ; 22(19)2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34638543

RESUMO

Monensin is an ionophore for monovalent cations, which is frequently used to prevent ketosis and to enhance performance in dairy cows. Studies have shown the rumen bacteria Prevotella bryantii B14 being less affected by monensin. The present study aimed to reveal more information about the respective molecular mechanisms in P.bryantii, as there is still a lack of knowledge about defense mechanisms against monensin. Cell growth experiments applying increasing concentrations of monensin and incubations up to 72 h were done. Harvested cells were used for label-free quantitative proteomics, enzyme activity measurements, quantification of intracellular sodium and extracellular glucose concentrations and fluorescence microscopy. Our findings confirmed an active cell growth and fermentation activity of P.bryantii B14 despite monensin concentrations up to 60 µM. An elevated abundance and activity of the Na+-translocating NADH:quinone oxidoreductase counteracted sodium influx caused by monensin. Cell membranes and extracellular polysaccharides were highly influenced by monensin indicated by a reduced number of outer membrane proteins, an increased number of certain glucoside hydrolases and an elevated concentration of extracellular glucose. Thus, a reconstruction of extracellular polysaccharides in P.bryantii in response to monensin is proposed, which is expected to have a negative impact on the substrate binding capacities of this rumen bacterium.


Assuntos
Transporte de Íons/efeitos dos fármacos , Monensin/farmacologia , Polissacarídeos Bacterianos/metabolismo , Prevotella/efeitos dos fármacos , Ionóforos de Sódio/farmacologia , Animais , Bovinos , Membrana Celular/metabolismo , Farmacorresistência Bacteriana/genética , Farmacorresistência Bacteriana/fisiologia , Perfilação da Expressão Gênica , Transporte de Íons/fisiologia , Consumo de Oxigênio/efeitos dos fármacos , Prevotella/crescimento & desenvolvimento , Quinona Redutases/metabolismo , Rúmen/microbiologia , Sódio/metabolismo
11.
Biomacromolecules ; 22(9): 4016-4026, 2021 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-34510906

RESUMO

The importance of conformational rigidity on macroscopic rheological properties was revealed using two model polysaccharides, namely, xanthan gum and hyaluronic acid. Xanthan gum has a rigid tertiary conformation due to its ordered double-helical structure, and the interactions between the tertiary structures result in the formation of a network/quaternary structure. In comparison, hyaluronic acid possesses a relatively flexible tertiary conformation due to its secondary random coil structure. Xanthan gum exhibits a much stronger shear thinning and more solidlike behavior compared to hyaluronic acid, owing to its network/quaternary structure. The rigid tertiary structure and the presence of a network/quaternary structure also endow xanthan gum with better resistance against environmental changes (e.g., salt and/or urea addition, temperature change) compared to hyaluronic acid. The network/quaternary structure allows xanthan gum to form gels with chitosan via electrostatic interactions when using the vapor-induced gelation technique, which is not possible for hyaluronic acid due to its flexible tertiary conformation under similar conditions.


Assuntos
Hidrogéis , Polissacarídeos Bacterianos , Ácido Hialurônico , Conformação Molecular , Reologia
12.
N Engl J Med ; 385(12): 1104-1115, 2021 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-34525285

RESUMO

BACKGROUND: Typhoid fever caused by multidrug-resistant H58 Salmonella Typhi is an increasing public health threat in sub-Saharan Africa. METHODS: We conducted a phase 3, double-blind trial in Blantyre, Malawi, to assess the efficacy of Vi polysaccharide typhoid conjugate vaccine (Vi-TCV). We randomly assigned children who were between 9 months and 12 years of age, in a 1:1 ratio, to receive a single dose of Vi-TCV or meningococcal capsular group A conjugate (MenA) vaccine. The primary outcome was typhoid fever confirmed by blood culture. We report vaccine efficacy and safety outcomes after 18 to 24 months of follow-up. RESULTS: The intention-to-treat analysis included 28,130 children, of whom 14,069 were assigned to receive Vi-TCV and 14,061 were assigned to receive the MenA vaccine. Blood culture-confirmed typhoid fever occurred in 12 children in the Vi-TCV group (46.9 cases per 100,000 person-years) and in 62 children in the MenA group (243.2 cases per 100,000 person-years). Overall, the efficacy of Vi-TCV was 80.7% (95% confidence interval [CI], 64.2 to 89.6) in the intention-to-treat analysis and 83.7% (95% CI, 68.1 to 91.6) in the per-protocol analysis. In total, 130 serious adverse events occurred in the first 6 months after vaccination (52 in the Vi-TCV group and 78 in the MenA group), including 6 deaths (all in the MenA group). No serious adverse events were considered by the investigators to be related to vaccination. CONCLUSIONS: Among Malawian children 9 months to 12 years of age, administration of Vi-TCV resulted in a lower incidence of blood culture-confirmed typhoid fever than the MenA vaccine. (Funded by the Bill and Melinda Gates Foundation; ClinicalTrials.gov number, NCT03299426.).


Assuntos
Polissacarídeos Bacterianos , Febre Tifoide/prevenção & controle , Vacinas Tíficas-Paratíficas , Criança , Pré-Escolar , Método Duplo-Cego , Feminino , Seguimentos , Humanos , Incidência , Lactente , Análise de Intenção de Tratamento , Malaui , Masculino , Vacinas Meningocócicas/efeitos adversos , Polissacarídeos Bacterianos/efeitos adversos , Salmonella typhi , Febre Tifoide/epidemiologia , Vacinas Tíficas-Paratíficas/efeitos adversos , Vacinas Conjugadas
13.
Appl Microbiol Biotechnol ; 105(19): 7439-7450, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34536104

RESUMO

Activating the defense response of plants by elicitors provides a promising method for biocontrol of pathogens. The homogeneous octaose (RiOc) which was depolymerized from the succinoglycan Riclin was investigated as a novel elicitor to activate the immune system of potato (Solanum tuberosum L.). After foliar spray, RiOc quickly induced accumulation of reactive oxygen species in potato leaves in a dose-dependent manner. Transcriptomic analysis revealed that 2712 out of 30,863 genes were differentially expressed at the early stage (24 h), while 367 of them were changed later (72 h). Results from the transcriptome and quantitative RT-PCR suggested that RiOc was probably perceived by the receptor LYK3 and it activated the MKK2/3/9/-MPK6/7 signaling cascade and promoted the salicylic acid-mediated defense response. Meanwhile, RiOc changed the metabolome profile of potato leaves over time as demonstrated by the 1H NMR-based metabolomic analysis. Homeostasis of amino acids was affected at the early stage while the secondary metabolism was strengthened later. More importantly, RiOc significantly reduced the severity of potato leaf lesions caused by the late blight pathogen Phytophthora infestans. In conclusion, RiOc effectively improved the resistance of potato to P. infestans by eliciting the salicylic acid-mediated defense response. RiOc becomes a promising carbohydrate-based elicitor for biocontrol of plant pathogens. KEY POINTS: • Homogeneous Riclin octaose was a novel elicitor for biocontrol of plant pathogens. • Riclin octaose primed the salicylic acid-mediated defense response of potato plants. • Riclin octaose changed the metabolome profile of potato leaves over time.


Assuntos
Solanum tuberosum , Metabolômica , Polissacarídeos Bacterianos , Transcriptoma
14.
Eur J Pharm Sci ; 167: 106011, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34537375

RESUMO

The aim of this study was to evaluate the in vitro antifungal action of a diphenyl diselenide-loaded poly(ε-caprolactone) nanocapsules suspension (NC-1) and incorporate it into a gellan gum hydrogel formulation in order to assess its in vivo efficacy in an animal model of vulvovaginal candidiasis. Nanocapsules suspensions containing the compound (NC-1 ∼ 5 mg/mL) or not (NC-B) were prepared by the interfacial deposition of preformed polymer method. To estimate in vitro antifungal effect, the broth microdilution test was applied. The results showed that NC-1 had equal or lower MIC values when compared to free compound against fifteen Candida strains. Following, the hydrogel was prepared by direct thickening of the nanocapsules suspension by gellan gum addition. The animal model of vulvovaginal candidiasis was induced by infecting female Swiss mice with Candida albicans strains. The animals were topically treated with 20 µL of hydrogels (NC-1 and free compound - 0.1 mg of diphenyl diselenide/once a day for seven days) and then the total fungal burden was assessed after the euthanasia. The results showed that the hydrogels presented pH in the acidic range, compound content close to theoretical value, homogeneous particle distribution with nanometric size, high physicochemical and microbiological stability as well as great bioadhesive property. The nano-based presented superior pharmacological action in comparison to the hydrogel containing non-encapsulated diphenyl diselenide. The results demonstrated that the nanoencapsulation maintained the effective antifungal action of diphenyl diselenide. The nano-based hydrogel formulation may be considered a promising approach against vulvovaginal candidiasis.


Assuntos
Candidíase Vulvovaginal , Nanocápsulas , Animais , Antifúngicos/uso terapêutico , Derivados de Benzeno , Candida , Candidíase Vulvovaginal/tratamento farmacológico , Feminino , Humanos , Hidrogéis/uso terapêutico , Camundongos , Nanocápsulas/uso terapêutico , Compostos Organosselênicos , Polissacarídeos Bacterianos
15.
ACS Biomater Sci Eng ; 7(10): 4898-4913, 2021 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-34533303

RESUMO

Cell encapsulation strategies using hydrogel beads have been considered as an alternative to immunosuppression in cell-based therapies. They rely on layer-by-layer (LbL) deposition of polymers to tune beads' permeability, creating a physical barrier to the host immune system. However, the LbL approach can also create diffusion barriers, hampering the flow of essential nutrients and therapeutic cell products. In this work, the polyelectrolyte complex (PEC) methodology was used to circumvent the drawbacks of the LbL strategy by inducing hydrogel bead formation through the interaction of anionic methacrylated gellan gum (GG-MA) with cationic poly-l-lysine (PLL). The interfacial complexation between both polymers resulted in beads with a cell-friendly GG-MA hydrogel core surrounded by a PEC semipermeable membrane. The beads showed great in vitro stability over time, a semi-permeable behavior, and supported human adipose-derived stem cell encapsulation. Additionally, and regarding immune recognition, the in vitro and in vivo studies pointed out that the hydrogel beads behave as an immunocompatible system. Overall, the engineered beads showed great potential for hydrogel-mediated cell therapies, when immunoprotection is required, as when treating different metabolic disorders.


Assuntos
Polilisina , Polissacarídeos Bacterianos , Humanos , Hidrogéis , Polieletrólitos
16.
ACS Chem Biol ; 16(9): 1671-1679, 2021 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-34469105

RESUMO

Vaccination represents the most effective way to prevent invasive pneumococcal diseases. The glycoconjugate vaccines licensed so far are obtained from capsular polysaccharides (CPSs) of the most virulent serotypes. Protection is largely limited to the specific vaccine serotypes, and the continuous need for broader coverage to control the outbreak of emerging serotypes is pushing the development of new vaccine candidates. Indeed, the development of efficacious vaccine formulation is complicated by the high number of bacterial serotypes with different CPSs. In this context, to simplify vaccine composition, we propose the design of new saccharide fragments containing chemical structures shared by different serotypes as cross-reactive and potentially cross-protective common antigens. In particular, we focused on Streptococcus pneumoniae (Sp) 19A and 19F. The CPS repeating units of Sp 19F and 19A are very similar and share a common structure, the disaccharide ManNAc-ß-(1→4)-Glc (A-B). Herein, we describe the synthesis of a small library of compounds containing different combinations of the common 19F/19A disaccharide. The six new compounds were tested with a glycan array to evaluate their recognition by antibodies in reference group 19 antisera and factor reference antisera (reacting against 19F or 19A). The disaccharide A-B, phosphorylated at the upstream end, emerged as a hit from the glycan array screening because it is strongly recognized by the group 19 antisera and by the 19F and 19A factor antisera, with similar intensity compared with the CPSs used as controls. Our data give a strong indication that the phosphorylated disaccharide A-B can be considered a common epitope among different Sp 19 serotypes.


Assuntos
Epitopos/química , Glicoconjugados/análise , Proteínas Imobilizadas/química , Polissacarídeos Bacterianos/análise , Anticorpos/química , Técnicas Biossensoriais , Reações Cruzadas , Glicoconjugados/metabolismo , Hexosaminas/química , Polissacarídeos Bacterianos/metabolismo , Sorogrupo , Soro/química , Espectrometria de Fluorescência , Streptococcus pneumoniae/metabolismo , Propriedades de Superfície
17.
PLoS One ; 16(9): e0257026, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34473773

RESUMO

Mucoid Pseudomonas aeruginosa is a prevalent cystic fibrosis (CF) lung colonizer, producing an extracellular matrix (ECM) composed predominantly of the extracellular polysaccharide (EPS) alginate. The ECM limits antimicrobial penetration and, consequently, CF sufferers are prone to chronic mucoid P. aeruginosa lung infections. Interactions between cations with elevated concentrations in the CF lung and the anionic EPS, enhance the structural rigidity of the biofilm and exacerbates virulence. In this work, two large mucoid P. aeruginosa EPS models, based on ß-D-mannuronate (M) and ß-D-mannuronate-α-L-guluronate systems (M-G), and encompassing thermodynamically stable acetylation configurations-a structural motif unique to mucoid P. aeruginosa-were created. Using highly accurate first principles calculations, stable coordination environments adopted by the cations have been identified and thermodynamic stability quantified. These models show the weak cross-linking capability of Na+ and Mg2+ ions relative to Ca2+ ions and indicate a preference for cation binding within M-G blocks due to the smaller torsional rearrangements needed to reveal stable binding sites. The geometry of the chelation site influences the stability of the resulting complexes more than electrostatic interactions, and the results show nuanced chemical insight into previous experimental observations.


Assuntos
Alginatos/metabolismo , Cátions/metabolismo , Fibrose Cística/metabolismo , Matriz Extracelular/metabolismo , Modelos Moleculares , Polissacarídeos Bacterianos/metabolismo , Infecções por Pseudomonas/metabolismo , Pseudomonas aeruginosa/metabolismo , Ânions/metabolismo , Sítios de Ligação , Biofilmes , Cálcio/metabolismo , Reagentes para Ligações Cruzadas/metabolismo , Fibrose Cística/microbiologia , Ácidos Hexurônicos/química , Ácidos Hexurônicos/metabolismo , Ligação de Hidrogênio , Magnésio/metabolismo , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/patogenicidade , Sódio/metabolismo , Termodinâmica , Virulência
18.
J Pharm Biomed Anal ; 205: 114340, 2021 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-34474230

RESUMO

Burkholderia pseudomallei causes melioidosis - an infectious disease with high mortality. Its varied clinical manifestations and resistance to many antibiotics make it a potential biothreat agent and calls for a robust diagnostic assay and effective vaccines. Bacterial cell surface polysaccharides are considered a valuable target for diagnostics and as protective antigen candidates. This study characterized the structure of polysaccharides of B. pseudomallei clinical strain from Hainan, China. A novel structural domain [→3-(α-D-Manp-1→3-α-D-Manp)2-2Me-α-L-6dTalp-1→] was identified by chemical analysis, gas chromatography-mass spectrometry (GC-MS), and 1D/2D nuclear magnetic resonance (NMR) spectroscopy. Immunofluorescence and enzyme-linked immunosorbent assay (ELISA) showed that the serum antibodies against the purified polysaccharide antigen could recognize and bind specifically to B. pseudomallei strains. Additionally, the assays revealed cross-reactivity with polysaccharides from different clinical strains. The polysaccharide antigen also exhibited a strong reaction with the sera from melioidosis patients. Thus, the pentasaccharide repeating unit residue could be a potential candidate antigen for the melioidosis serodiagnosis and vaccine development.


Assuntos
Burkholderia pseudomallei , Melioidose , Anticorpos Antibacterianos , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Melioidose/diagnóstico , Polissacarídeos Bacterianos
19.
Mater Sci Eng C Mater Biol Appl ; 128: 112303, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34474854

RESUMO

Macrophages, the primary effector cells in the immune response, respond rapidly to the physical or chemical properties of biomaterial implants. Balanced macrophage polarization, phagocytosis, and migration would be beneficial for implant success and tissue regeneration. Here, we investigated macrophage phenotypic changes, phagocytosis, and migration in response to RGD functionalized surfaces and changes in stiffness of gellan gum hydrogels. We also inhibited the RhoA pathway. The compressive moduli ranged from ~5 to 30 kPa. Cell population and cell spreading area of classically activated macrophages (M(LPS)) and alternatively activated macrophages (M(IL-4)) are promoted on RGD modified hydrogel. ROCK inhibitor induced the opposite effect on the cell spreading of both M(LPS) and M(IL-4) macrophages on RGD modified hydrogels. Macrophage polarization was found to be stiffness-driven and regulated by the RGD motif and blocked by the RhoA pathway. RGD functionalized hydrogel shifted M(IL-4) cells toward a more pro-inflammatory phenotype, while ROCK inhibition shifted M(LPS) cells to a more anti-inflammatory phenotype. Both M(LPS) and M(IL-4) cells on untreated hydrogels shifted to a more pro-inflammatory phenotype in the presence of aminated-PS particles. The RGD motif had a significant impact on cellular uptake, whereas cellular uptake was stiffness driven on untreated hydrogels. Cell migration of M(LPS) and M(IL-4) cells had ROCK-dependent migration. The stiffness of gellan gum hydrogels had no influence on macrophage migration rate. Collectively, our results showed that gellan gum hydrogels can be used to direct immune response, macrophage infiltration, and phagocytosis.


Assuntos
Hidrogéis , Ativação de Macrófagos , Hidrogéis/farmacologia , Macrófagos , Oligopeptídeos , Polissacarídeos Bacterianos
20.
Biochemistry ; 60(37): 2836-2843, 2021 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-34505775

RESUMO

Campylobacter jejuni is a Gram-negative, pathogenic bacterium that causes campylobacteriosis, a form of gastroenteritis. C. jejuni is the most frequent cause of food-borne illness in the world, surpassing Salmonella and E. coli. Coating the surface of C. jejuni is a layer of sugar molecules known as the capsular polysaccharide that, in C. jejuni NCTC 11168, is composed of a repeating unit of d-glycero-l-gluco-heptose, d-glucuronic acid, d-N-acetyl-galactosamine, and d-ribose. The d-glucuronic acid moiety is further amidated with either serinol or ethanolamine. It is unknown how these modifications are synthesized and attached to the polysaccharide. Here, we report the catalytic activities of two previously uncharacterized, pyridoxal phosphate (PLP)-dependent enzymes, Cj1436 and Cj1437, from C. jejuni NCTC 11168. Using a combination of mass spectrometry and nuclear magnetic resonance, we determined that Cj1436 catalyzes the decarboxylation of l-serine phosphate to ethanolamine phosphate. Cj1437 was shown to catalyze the transamination of dihydroxyacetone phosphate to (S)-serinol phosphate in the presence of l-glutamate. The probable routes to the ultimate formation of the glucuronamide substructures in the capsular polysaccharides of C. jejuni are discussed.


Assuntos
Cápsulas Bacterianas/enzimologia , Cápsulas Bacterianas/metabolismo , Campylobacter jejuni/enzimologia , Cápsulas Bacterianas/genética , Proteínas de Bactérias/química , Infecções por Campylobacter/microbiologia , Campylobacter jejuni/metabolismo , Metabolismo dos Carboidratos , Heptoses/biossíntese , Polissacarídeos/biossíntese , Polissacarídeos Bacterianos/biossíntese , Polissacarídeos Bacterianos/genética , Polissacarídeos Bacterianos/metabolismo , Fosfato de Piridoxal/metabolismo
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