Selected phytochemical bioactive compounds as quorum sensing inhibitors

Bacterial infections remain an important problem for human health. The control of bacterial infections has been traditionally treated by inhibiting microbial growth using different types of antibiotics. However, the ability of different bacteria to resist the inhibitory action of antibiotics has become a global problem. In fact, there is an important need for the development of new antimicrobials that act on novel bacterial targets. Many pathogenic bacteria control their population and regulate gene expression in response to their cell population density using diffusible signalling com¬pounds. This type of communication has been referred to as “quorum sensing” (QS). This phenomenon can be essential for the synchronization of the virulence production factors, which make it an attractive therapeutic target. Therefore, the search of non-toxic compounds, which inhibit QS and so, the virulence of pathogenic bacteria can bring new alternatives for the treatment of bacterial infections in humans. In this work, we made an attempt to screen the anti-QS activity of 11 bioactive compounds extracted from fruits and vegetables using the biosensor strain, Chromobacterium violaceum. The anti-QS activity was determined quantifying the violacein production of the biosensor strain at three concentrations (50, 100 and 200 µg/ml). At least five of the tested compounds (cinnamaldehyde, pomegranate extracts, ellagic acid resveratrol and rutin) showed anti-QS activity against the biosensor strain. The obtained results showed the potential of bioactive compounds extracted from fruits and vegetables to be used as a new category of anti-pathogenic compounds against bacterial infections.Fil: Truchado , P.. Consejo Superior de Investigaciones Cientificas. Center For Research In Agricultural Genomics.; EspañaFil: Tomás Barberán, F.. Consejo Superior de Investigaciones Cientificas. Center For Research In Agricultural Genomics.; EspañaFil: Allende, A.. Consejo Superior de Investigaciones Cientificas. Center For Research In Agricultural Genomics.; EspañaFil: Ponce, Alejandra Graciela. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentin

Harnessing agricultural microbiomes for human pathogen control

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A comparison of methods to assess the antimicrobial activity of nanoparticle combinations on bacterial cells

Copyright: © 2018 Bankier et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.BACKGROUND: Bacterial cell quantification after exposure to antimicrobial compounds varies widely throughout industry and healthcare. Numerous methods are employed to quantify these antimicrobial effects. With increasing demand for new preventative methods for disease control, we aimed to compare and assess common analytical methods used to determine antimicrobial effects of novel nanoparticle combinations on two different pathogens. METHODS: Plate counts of total viable cells, flow cytometry (LIVE/DEAD BacLight viability assay) and qPCR (viability qPCR) were used to assess the antimicrobial activity of engineered nanoparticle combinations (NPCs) on Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria at different concentrations (0.05, 0.10 and 0.25 w/v%). Results were analysed using linear models to assess the effectiveness of different treatments. RESULTS: Strong antimicrobial effects of the three NPCs (AMNP0-2) on both pathogens could be quantified using the plate count method and flow cytometry. The plate count method showed a high log reduction (>8-log) for bacteria exposed to high NPC concentrations. We found similar antimicrobial results using the flow cytometry live/dead assay. Viability qPCR analysis of antimicrobial activity could not be quantified due to interference of NPCs with qPCR amplification. CONCLUSION: Flow cytometry was determined to be the best method to measure antimicrobial activity of the novel NPCs due to high-throughput, rapid and quantifiable results.Peer reviewe

THE QUALITY OF HONEY FOR BEES AND MAN

Honey is used both as food ingredient and in a variety of treatments for diverse ailments. For this reason, consumer expectation of its quality and purity is particularly high. The aim of the BEE SHOP Honey Department was the evaluation of honey quality and authenticity, through the development of new instrument for the verification of the botanical origin and the presence of impurities. Honey quality can be important also for the colony itself and therefore the Honey Department focused on the physiological properties of honey which can be beneficial for honeybees and for the prevention of bee diseases. Testing the origin of honeybees is also important to enforce the EC directive for organic beekeeping, since the use of regional bee strains is an important quality criterion for organic honey. To identify the origin of the honeybee the BEE SHOP Honey Department has developed a DNA based diagnostic tool. Through the analysis of honey and nectar samples by HPLC-MS-MS methods, suitable markers were detected for Robinia, Tilia, Citrus, Eucalyptus and chestnut unifloral honeys, and the following phytochemicals have been proposed for the determination of honey floral origins: myricetin, tricetin and luteolin for Eucalyptushoney, kynurenic acid related compounds for chestnut honey, terpenoids for Linden honey, hesperetin for Citrus honey, kaempferol rhamnosides for Acacia (Robinia) honey. Two novel protocols were introduced for the evaluation of honey quality: DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) and HR-NMR (High Resolution Nuclear Magnetic Resonance). These techniques, coupled with appropriate multivariate statistical analysis, demonstrated to be suitable for the verification of botanical origin and the detection of honey adulteration by sugar syrups. The HR-NMR method seems to be suitable also for a quantitative determination of the adulteration levels. A new sensitive enzyme-linked immunoassay (ELISA) for the quantitative determination of apalbumin1a major compound of the royal jelly (RJ) proteins in honey has been developed. This protein can be used as a marker for honey quality because its concentration varies with the botanical origin. The highest content was determined in chestnut honey, in comparison with acacia and rape honey, while the lowest amount was detected in honey obtained supplying bee colony with saccharose syrup. The antimicrobial potential of honey based on proteins of honeybee origin was tested by microtiter based assays. The inhibition of P. larvae growth was observed in the protein fraction of cherry and rape honeys and honeydew. Moreover, a protein fraction corresponding to apalbumin2a has been identified in honey. This protein, purified from RJ, had specific antibiotic properties against P. larvae. The anti quorum-sensing (QS) activities of honeys with different floral origin have been evaluated, using bacterial strains in which quorum-sensing activated the pigment violacein. 29 honey samples inhibited QS even at the lowest concentration. The anti-QS activity was concentration-dependent and relied on the floral origin. Among all honeys, chestnut and linden samples were the strongest quorum-sensing inhibitors (QSI)

Harnessing agricultural microbiomes for human pathogen control

info:eu-repo/semantics/publishedVersio