Antibacterial Effect of Cell-Free Supernatant from Lactobacillus pentosus L-36 against Staphylococcus aureus from Bovine Mastitis

This study sought to analyze the main antibacterial active components of Lactobacillus pentosus (L. pentosus) L-36 cell-free culture supernatants (CFCS) in inhibiting the growth of Staphylococcus aureus (S. aureus), to explore its physicochemical properties and anti-bacterial mechanism. Firstly, the main antibacterial active substance in L-36 CFCS was peptides, which inferred by adjusting pH and enzyme treatment methods. Secondly, the physicochemical properties of the antibacterial active substances in L-36 CFCS were studied from heat, pH, and metal ions, respectively. It demonstrated good antibacterial activity when heated at 65 °C, 85 °C and 100 °C for 10 and 30 min, indicating that it had strong thermal stability. L-36 CFCS had antibacterial activity when the pH value was 2–6, and the antibacterial active substances became stable with the decrease in pH value. After 10 kinds of metal ions were treated, the antibacterial activity did not change significantly, indicating that it was insensitive to metal ions. Finally, scanning electron microscopy, transmission electron microscopy and fluorescence probe were used to reveal the antibacterial mechanism of S. aureus from the aspects of cell morphology and subcellular structure. The results demonstrated that L-36 CFCS could form 1.4–2.3 nm pores in the cell membrane of S. aureus, which increased the permeability of the bacterial cell membrane, resulting in the depolarization of cell membrane potential and leakage of nucleic acid protein and other cell contents. Meanwhile, a large number of ROS are produced and accumulated in the cells, causing damage to DNA, and with the increase in L-36 CFCS concentration, the effect is enhanced, and finally leads to the death of S. aureus. Our study suggests that the main antibacterial active substances of L-36 CFCS are peptides. L-36 CFCS are thermostable, active under acidic conditions, insensitive to metal ions, and exhibit antibacterial effects by damaging cell membranes, DNA and increasing ROS. Using lactic acid bacteria to inhibit S. aureus provides a theoretical basis for the discovery of new antibacterial substances, and will have great significance in the development of antibiotic substitutes, reducing bacterial resistance and ensuring animal food safety.     

Electrochemically modified piezoelectric crystal biosensor for detection of Staphylococcus aureus

Electropolymerized o-phenylenediamine film is used as a functional coating for the immobilization of anti-S. aureus antibody on the surface of a gold-plated piezoelectric crystal, and this piezoelectric immunosensor is applied to detect S. aureus. The frequency shift (F = F20s - F380s, Hz) between the frequency at the 20th second (after the addition of sample, F20s) and that at 380 seconds later (F380s) was introduced to construct a calibration graph, and shortening of assay time was achieved. The S. aureus concentrations in the range of 105-109 cells/mL can be detected by this system.     

Surface-imprinted polyurethane having affinity sites for ampicillin

Affinity sites for an antibacterial drug, ampicillin, were created on the surface of polyurethane using the technique of non-covalent molecular imprinting. This was achieved by polymerizing aminophenylboronic acid in the presence of the ampicillin as a template. The extent of adsorption of the drug by the imprinted surface is nearly five times higher than the non-imprinted surface. The in vitro release studies have shown that the drug is retained for a prolonged period on the imprinted surface while it is rapidly released from the non-imprinted surface. These modified materials were subjected to interactions with two bacterial strains, E. Coli and S. aureus. These species could not adhere to the imprinted surface, further showing the ability of the surface to retain the drug for a prolonged period of time. The non-imprinted surface retained the bacterial strains, reflecting the lack of the drug on the surface. This novel approach seems to be useful for creating surfaces capable of retaining components of interest through non-covalent interactions to impart specific features, such as improved blood compatibility and antibacterial properties. [diagram in text].     

Traditional uses,phytochemistry, pharmacology and other potential applications of Vitellaria paradoxa Gaertn. (Sapotaceae): A review

Vitellaria paradoxa Gaertn. is a multipurpose medicinal plant of the family Sapotaceae, and it has been widely used usually in the clinical traditional medicine as remedy for a wide range of diseases for several decades. In addition, the plant has also found applications in confectionery, cosmetics and soaps, and pharmaceuticals both locally and internationally. V. paradoxa, which has been identified with >150 phytoconstituents, is rich in oleanane-type triterpene acids and glycosides, such as paradoxosides A-E, tieghemelin A, parkiosides A-C, bassic acid, as well as flavonoids such as quercetin and catechin-type compounds. The extracts and the active constituents of V. paradoxa have been investigated for various pharmacological activities, including but not limited to anticancer, melanogenesis-inhibitory, antibacterial, anti-diabetic, antioxidant, anti-inflammatory, anti-diarrhoeal, and antifungal activities. Additionally, V. paradoxa has also been utilized in nanoparticles (NPs) synthesis. These NPs among other things have shown significant antinociceptive and antiedematogenic activities as well as environmental friendly adsorptive properties for the removal of pollutants from pharmaceutical effluents. Overall, this review comprehensively examines the traditional uses, phytochemistry, pharmacology, toxicology, clinical studies, and nanoparticles synthesized from V. paradoxa and their applications.     

The visualisation of the targeting of phospholipid liposomes to bacteria

Anionic and cationic phospholipid liposomes have been prepared from dipalmitoylphosphatidylcholine (DPPC) — phosphatidylinositol (PI) and DPPC-cholesterol-stearylamine (SA) mixtures over a range of composition and targeted to biofilms of the skin-associated bacterium Staphylococcus epidermidis to establish the optimum PI and SA content for targeting. The interaction of liposomes of optimum composition with the bacteria were visualized by electron microscopy using negative staining with uranyl acetate and phosphotungstic acid. It has been demonstrated that the liposomes absorb extensively to the bacterial surface. Immunoliposomes have been prepared with a covalently linked monoclonal antibody raised to antigenic determinants on the surface of the oral bacterium Streptococcus oralis. The targeting of the immunoliposomes to this bacterium has been visualized using a second gold labelled anti-antibody. As for the anionic and cationic liposomes the immunoliposomes adsorb to the surface of the bacteria. The results add support to the concept of using liposomes for the delivery of bactericides or therapeutic agents to bacteria.     

ANTIBACTERIAL ACTIVITY OF SINGLE AND MIXED AMMONIUM AND PHOSPHONIUM SALTS GRAFTED ON "GEL-TYPE" STYRENE-DIVINYLBENZENE COPOLYMERS*

1.INTRODUCTIONThesynthesisofpolymer-supported"onium"salts(ammoniumandphosphonium)(1~5(wasdiscussedindetailduetothewidefieldofutilizationas:polarstationaryphasesforanionchromatography(6(,polymericreagentsfortrans-quaternizationreactions(7,8(,phase-transfercatalysts(9~13(andpolycationicbiocides(14~17(.Manychemicalmaterialssuchasozone,liquidchlorine,sodiumhydrochloride,s.a.,havebeenlargelyusedtosterilizeairandwater.Suchmaterialsrequirespecialequipmentandcarelessusemaycauseenvironmentalpolluti…     

Development of an Amperometric Immunosensor for the Quantification of Staphylococcus aureus Using Self‐Assembled Monolayer‐Modified Electrodes as Immobilization Platforms

Amperometric immunosensors for the detection and quantification of S. aureus using MPA self‐assembled monolayer modified electrodes for the immobilization of the immunoreagents are reported. Two different immunosensor configurations were compared. A competitive mode, in which protein A‐bearing S. aureus cells and antiRbIgG labeled with horseradish peroxidase (HRP) compete for the binding sites of RbIgG immobilized onto the 3‐mercaptopropionic acid (MPA) modified electrode, was evaluated. Moreover, a sandwich configuration in which S. aureus cells were immobilized onto the MPA SAM, and RbIgG and antiRbIgG labeled with HRP were further linked to the electrode surface, was also tested. In both cases, TTF was used as the redox mediator of the HRP reaction with H₂O₂, and it was co‐immobilized onto the MPA‐modified gold electrode. After optimization of the working variables for both configurations, the analytical performance of the amperometric measurements carried out at 0.00 V (vs. Ag/AgCl) showed that the competitive immunosensor exhibited a lower limit of detection (1.6×10⁵ S. aureus cells mL^?1), as well as a better repeatability and reproducibility of the measurements.     

Influence of satellite groups on telechelic antimicrobial functions of polyoxazolines

The antimicrobial activity of poly(alkyloxazoline) telechelics with one quaternary N,N-dimethyldodecylammonium (DDA) end group was found to be greatly controlled by the non-bioactive distal end group, the so-called satellite group. In systematic investigations, the nature of the latter groups was varied to explore the mechanism of the satellite effect. To this end, poly(2-alkyl-1,3-oxazoline)s (alkyl = ethyl, methyl) with a DDA-group at the terminating end and varying alkyl, aminoalkyl, and polyphenyloxazoline block satellite groups, have been synthesized. Poly(oxazoline) derivatives with polydispersity indices of 1.06-1.20 and molecular weights from 2,200 to 12,800 g . mol(-1) could be obtained. The macromolecular structures have been confirmed by NMR spectroscopy and ESI-MS measurements. The polymers were investigated with regard to their antibacterial efficiency towards the Gram-positive bacterium Staphylococcus aureus and the Gram-negative bacterium Escherichia coli. It was found that the introduction of alkyl chain satellites of 4-10 carbon atoms in length afforded antimicrobial activity of the polymers against both microbes that was about 2-3 times higher than that of the well-known structurally comparable low molecular weight biocide, dodecyltrimethylammonium chloride (DTAC). Based on the antimicrobial effects of the investigated polymers, a mechanism for the satellite effect was proposed.     

Microcalorimetric Study of the Action of Yb^3＋ ion on the Growth of Staphylococcus aureus

A microcalorimetric method was used to evaluate the action of Yb^3 ions onthe growth metabolism of Staphylococcus aureus.The power-time curves of the growth metabolism of Staphylo.coccus aureus and the action of Yb^3 ions were obtained by us-ing stopped-flow method at 37 ℃. For evaluation of the action,the growth rate constants ( k1 and k2) for the log phase 1, log phase 2, and the total heat effect (Qtotal) for Staphylococcus aureus were determined. The results show that Yb^3 ions at low concentrations have the stimnlatory effect on Staphylococcus au-reus and that Yb^3 ions at higher concentration could inhibit its growth.     

Synthesis,characterization, and antibacterial activity of 6-Chloro-8-methyl-2-oxo-2H-chromene-3-carboxylic acid ethyl ester

The title compound was synthesized by reacting 2-hydroxy-4-methoxy-benzaldehyde with diethyl malonate in the presence of piperidine catalyst and ethanol as solvent. The chemical structure of the title compound was elucidated by elemental analysis, ¹H-NMR, and IR. The crystal structure was determined by X-ray diffraction data. It crystallizes in monoclinic crystal system, P2₁/c space group with unit cell parameters, a = 12.840(2) Å, b = 24.790(4) Å, c = 7.8544(13) Å, β = 98.035(5)°, V = 2475.5(7) ų, and Z = 8. The molecular and crystal structure of the title compound is stabilized by inter- and intramolecular interactions of the type C—H···O. The newly synthesized compound was screened for its antibacterial activity against two gram-positive and two gram-negative bacteria.