Coagulation performance evaluation of alginate as a natural coagulant for the treatment of turbid water

Alginates are quite abundant in nature as they occur both as a structural component in marine brown algae (Phaeophyceae) comprising up to 40% of dry matter and as capsular polysaccharides in soil bacteria. Alginic acid is the only polysaccharide, which naturally contains carboxyl groups in each constituent residue, and possesses various abilities for functional materials. Experiments were carried out for the water of turbidity 300 NTU. Alginate as such doesn't act as a coagulant instead it should be converted to calcium alginate by adding calcium ions. Calcium chloride was used for imparting calcium ions necessary for the reaction. The dosage of calcium was fixed as 50 mg/L, 75 mg/L, 100 mg/L, 150 mg/L, 200 mg/L, and alginate doses between 2 to 10 mg/L. Calcium dosage below 50 mg/L was not sufficient enough for the formation of egg-box structure which is responsible for the coagulation and flocculation process. For the mechanism of charge neutralization to take place effectively, calcium should be added first followed by alginate. pH and conductivity of the sample remain constant before and after the treatment. The dosage of alginate required for the treatment is less so the cost of treatment also will be very less, thus alginate can replace the usage of chemical coagulants like alum.

Total synthesis of the O-antigen repeating unit of Providencia stuartii O49 serotype through linear and one-pot assemblies

Capsular polysaccharides of pathogenic bacteria have been reported to be effective vaccines against diseases caused by them. Providencia stuartii is a class of enterobacteria of the family Providencia that is responsible for several antibiotic resistant infections, particularly urinary tract infections of patients with prolonged catheterization in hospital settings. Towards the goal of development of vaccine candidates against this pathogen, we herein report the total synthesis of a trisaccharide repeating unit of the O-antigen polysaccharide of the P. stuartii O49 serotype containing the →6)-β-ᴅ-Galp-(1→3)-β-ᴅ-GalpNAc(1→4)-α-ᴅ-Galp(1→ linkage. The synthesis of the trisaccharide repeating unit was carried out first by a linear strategy involving the [1 + (1 + 1 = 2)] assembly, followed by a one-pot synthesis involving [1 + 1 + 1] strategy from the corresponding monosaccharides. The one-pot method provided a higher yield of the protected trisaccharide intermediate (73%) compared to the two step synthesis (66%). The protected trisaccharide was then deprotected and N-acetylated to finally afford the desired trisaccharide repeating unit as its α-p-methoxyphenyl glycoside.

Synthesis and Preliminary Immunological Evaluation of a Pseudotetrasaccharide Related to a Repeating Unit of the Streptococcus pneumoniae Serotype 6A Capsular Polysaccharide

2-Aminoethyl glycoside of the pseudotetrasaccharide α-d-Glcp-(1→3)-α-l-Rhap-(1→3)-d-Rib-ol-(5-P-2)-α-d-Galp corresponding to a repeating unit of the Streptococcus pneumoniae type 6A capsular polysaccharide has been synthesized. A suitably protected pseudotrisaccharide α-d-Glcp-(1→3)-α-l-Rhap-(1→3)-d-Rib-ol with a free 5-OH group in the ribitol moiety and a 2-OH derivative of 2-trifluoroacetamidoethyl α-d-galactopyranoside have been efficiently prepared and then connected via a phosphate bridge using the hydrogen phosphonate procedure. Preliminary immunological evaluation of this pseudotetrasaccharide and the previously synthesized pseudotetrasaccharide corresponding to a repeating unit of the capsular polysaccharide of S. pneumoniae serotype 6B has shown that they contain epitopes specifically recognized by anti-serogroup 6 antibodies and are able to model well the corresponding capsular polysaccharides. Conjugates of the synthetic pseudotetrasaccharides with bovine serum albumin were shown to be immunogenic in mice.

Capsules and Extracellular Polysaccharides in Escherichia coli and Salmonella

Escherichia coli and Salmonella isolates produce a range of different polysaccharide structures that play important roles in their biology. E. coli isolates often possess capsular polysaccharides (K antigens), which form a surface structural layer. These possess a wide range of repeat-unit structures.

Virulence and pathogenicity factors of S. agalactiae strains isolated from pregnant women and newborns

BACKGROUND: Obstetric and neonatal infections caused by Steptococcus agalactiae are among the most significant perinatal infections. To date, intrapartum antibiotic prophylaxis is used to prevent the transmission of the pathogen to the child, however, the growth of antibiotic resistance and ineffectiveness of therapy against late-onset neonatal infection are its limitations. Vaccination is considered to be the most effective method for preventing diseases caused by S. agalactiae in both pregnant women and newborn babies. To identify promising vaccine targets and to develop alternative prevention approaches, it is necessary to study the virulence factors of S. agalactiae strains and their variability in the population. AIM: The aim of this study was to evaluate the variability of virulence and pathogenicity factors (capsular polysaccharides, pili, hypervirulent sequence type ST-17, biofilm-forming ability, antibiotic resistance) of S. agalactiae isolated from pregnant women and newborn infants in St. Petersburg, Russia. MATERIALS AND METHODS: We studied isolates of S. agalactiae out of clinical material samples obtained from pregnant women and newborns at the D.O. Ott Research Institute of Obstetrics, Gynecology, and Reproductology in 2018-2020. The PCR method was used to determine the types of capsular polysaccharides, pili, and strain affiliation with the hypervirulent sequencing type ST-17. Biofilm-forming ability was determined by the Christensen method. The antibiotic sensitivity was determined by disc diffusion. RESULTS: We examined 60 clinical isolates of S. agalactiae. The most common S. agalactiae serotypes were Ia, Ib, II, III, IV, and V; in total, these six serotypes accounted for 95.1% of all strains. The most common pili genotype was PI-1 + PI-2a (60%). Resistance to erythromycin was found in 36.7% of the strains, and a similar number of the strains were resistant to clindamycin. The ability to form biofilms was detected in 68% of the strains, and the increased ability was associated with the PI-2b pili allele. CONCLUSIONS: A hexavalent vaccine based on capsular polysaccharides of types Ia, Ib, II, III, IV, and V would have a 95% efficacy in this region. Stable distribution of different pili types is an important factor when using pili as vaccine targets. The high level of resistance of S. agalactiae strains to erythromycin and clindamycin indicates that isolates should be tested for sensitivity to these antibiotics before their use, and regular regional monitoring of antibiotic resistance of the pathogen to update clinical guidelines should be performed.

The Pneumococcal Divisome: Dynamic Control of Streptococcus pneumoniae Cell Division

Cell division in Streptococcus pneumoniae (pneumococcus) is performed and regulated by a protein complex consisting of at least 14 different protein elements; known as the divisome. Recent findings have advanced our understanding of the molecular events surrounding this process and have provided new understanding of the mechanisms that occur during the division of pneumococcus. This review will provide an overview of the key protein complexes and how they are involved in cell division. We will discuss the interaction of proteins in the divisome complex that underpin the control mechanisms for cell division and cell wall synthesis and remodelling that are required in S. pneumoniae, including the involvement of virulence factors and capsular polysaccharides.

Polysaccharide Vaccines: A Perspective on Non-Typhoidal Salmonella

Polysaccharides are often the most abundant antigens found on the extracellular surfaces of bacterial cells. These polysaccharides play key roles in interactions with the outside world, and for many bacterial pathogens, they represent what is presented to the human immune system. As a result, many vaccines have been or currently are being developed against carbohydrate antigens. In this review, we explore the diversity of capsular polysaccharides (CPS) in Salmonella and other selected bacterial species and explain the classification and function of CPS as vaccine antigens. Despite many vaccines being developed using carbohydrate antigens, the low immunogenicity and the diversity of infecting strains and serovars present an antigen formulation challenge to manufacturers. Vaccines tend to focus on common serovars or have changing formulations over time, reflecting the trends in human infection, which can be costly and time-consuming. We summarize the approaches to generate carbohydrate-based vaccines for Salmonella, describe vaccines that are in development and emphasize the need for an effective vaccine against non-typhoidal Salmonella strains.

A Randomized Safety Study of 13-Valent Pneumococcal Conjugated Vaccine and Post-Vaccination Immune Response to Streptococcus pneumoniae Serotypes in Adult Patients with Bronchial Asthma and Chronic Obstructive Pulmonary Disease

Background. Vaccination against pneumococcal infection is one of the priorities in improving the quality of treatment and prevention measures in adults with various pathologies. The effectiveness of vaccination is directly related to the individuals ability to form an adequate specific immunity. Aims the aim of the study was to assess the level of post-vaccination antibodies to capsular polysaccharides of S. pneumoniae in adult patients with bronchial asthma (BA) or chronic obstructive pulmonary disease (COPD) after administration of 13-valent conjugated pneumococcal vaccine (PCV13). Materials and methods. The ELISA method was used to determine the level of IgG antibodies to 12 capsular polysaccharides serotypes 1, 3, 4, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 23F of S. pneumoniae that are part of PCV13, and 2 serotypes 9N, 15B that are not part of the vaccines using research test systems developed on the basis of the I.I. Mechnikov Research Institute of Vaccines and Sera. Groups of adult patients 32 patients with BA and 33 with COPD who received basic treatment according to accepted international standards. The comparison group consists of 20 healthy patients who do not have comorbidities. In patients, vaccination was performed outside the acute period of the disease using PCV13. Results. Vaccination of PCV13 patients with BA and COPD does not lead to the development of exacerbations of the underlying disease, while unusual symptoms in the post-vaccination period, provided for by the drugs instructions, can rarely develop. A comparative analysis of changes in IgG antibodies conducted after 6 weeks relative to the initial level of IgG antibodies to S. pneumoniae capsular polysaccharides in adult patients and healthy vaccinated PCV13 showed the same increase in specific antibodies to 12 serotypes of pneumococcus. The difference was found only in relation to IgG antibodies to a mixture of polysaccharides included in the PCV13 vaccine, which were registered higher in patients with BA and COPD in the post-vaccination period (p 0.001) than in healthy patients. Conclusions. PCV13 vaccination of patients with BA and COPD is safe and is accompanied by the synthesis of IgG antibodies to capsular polysaccharides serotypes of S. pneumoniae similarly to the healthy group.