Enhancement of the ability of the porcine colonic microflora to resist colonisation by Salmonella poona, in an in vitro intestinal simulation

2002 ◽  
Vol 2002 ◽  
pp. 80-80
Author(s):  
K. Hillman
Keyword(s):  
Quorum Sensing ◽  
Culture Filtrate ◽  
Pathogenic Bacteria ◽  
Intestinal Microflora ◽  
Antagonistic Activity ◽  
Simulation System ◽  
Current Experiment ◽  
Subsequent Work ◽  
Colonic Microflora

The ability of the porcine intestinal microflora to resist the establishment of pathogenic bacteria has been demonstrated previously (Hillman et al, 1994). Subsequent work has shown that certain intestinal lactobacilli react to the presence of a culture filtrate derived from a coliform pathogen by increasing their antagonistic activity towards that pathogen (Hillman and Robertson, unpublished), indicating the presence of a quorum-sensing or related mechanism. The current experiment was devised to determine whether a similar effect could be produced within the entire porcine colonic microflora, using an in vitro simulation system.

Novel bacteria degrading N-acylhomoserine lactones and their use as quenchers of quorum-sensing-regulated functions of plant-pathogenic bacteria

Microbiology ◽  
2003 ◽  
Vol 149 (8) ◽  
pp. 1981-1989 ◽  
Author(s):  
Stéphane Uroz ◽  
Cathy D'Angelo-Picard ◽  
Aurélien Carlier ◽  
Miena Elasri ◽  
Carine Sicot ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Pathogenic Bacteria ◽  
Rhodococcus Erythropolis ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
In Planta ◽  
Signal Molecule ◽  
Violacein Production ◽  
Regulated Functions

Bacteria degrading the quorum-sensing (QS) signal molecule N-hexanoylhomoserine lactone were isolated from a tobacco rhizosphere. Twenty-five isolates degrading this homoserine lactone fell into six groups according to their genomic REP-PCR and rrs PCR-RFLP profiles. Representative strains from each group were identified as members of the genera Pseudomonas, Comamonas, Variovorax and Rhodococcus. All these isolates degraded N-acylhomoserine lactones other than the hexanoic acid derivative, albeit with different specificity and kinetics. One of these isolates, Rhodococcus erythropolis strain W2, was used to quench QS-regulated functions of other microbes. In vitro, W2 strongly interfered with violacein production by Chromobacterium violaceum, and transfer of pathogenicity in Agrobacterium tumefaciens. In planta, R. erythropolis W2 markedly reduced the pathogenicity of Pectobacterium carotovorum subsp. carotovorum in potato tubers. These series of results reveal the diversity of the QS-interfering bacteria in the rhizosphere and demonstrate the validity of targeting QS signal molecules to control pathogens with natural bacterial isolates.

Characterization of an antifungal soil bacterium and its antagonistic activities againstFusariumspecies

2003 ◽  
Vol 49 (4) ◽  
pp. 253-262 ◽  
Author(s):  
Yiu-Kwok Chan ◽  
Wayne A McCormick ◽  
Keith A Seifert
Keyword(s):  
Bacillus Subtilis ◽  
Culture Filtrate ◽  
Fusarium Species ◽  
Hyphal Growth ◽  
Antagonistic Activity ◽  
Plant Diseases ◽  
Ear Rot ◽  
In Planta ◽  
Head Blight

Bacteria were isolated from a cultivated soil and screened for antagonistic activity against Fusarium graminearum, a predominant agent of ear rot and head blight in cereal crops. Based on its in vitro effectiveness, isolate D1/2 was selected for characterization and identified as a strain of Bacillus subtilis by phenotypic tests and comparative analysis of its 16S ribosomal RNA gene (rDNA) sequence. It inhibited the mycelial growth of a collection of common fungal phytopathogens, including eight Fusarium species, three other ascomycetes, and one basidiomycete. The cell-free culture filtrate of D1/2 at different dilutions was active against macroconidium germination and hyphal growth of F. graminearum, depending on the initial macroconidium density. It induced the formation of swollen hyphal cells in liquid cultures of this fungus grown from macroconidia. A bioassay also demonstrated that D1/2 offered in planta protection against the damping-off disease in alfalfa seedlings caused by F. graminearum, while the type strain of B. subtilis was ineffective. Hence, B. subtilis D1/2 or its culture filtrate has potential application in controlling plant diseases caused by Fusarium.Key words: antifungal activity, Bacillus subtilis, biological control, biopesticide, Fusarium species.

Characterization and evaluation of probiotic potential in vitro and in situ of Lacticaseibacillus paracasei isolated from tenate cheese

2021 ◽  
Author(s):  
Reyna N Falfán-Cortes ◽  
Nancy Mora-Peñaflor ◽  
Carlos A Gómez-Aldapa ◽  
Esmeralda Rangel-Vargas ◽  
Otilio A Acevedo-Sandoval ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Fruits And Vegetables ◽  
Food Samples ◽  
Antagonistic Activity ◽  
Probiotic Potential ◽  
Fresh Cheese ◽  
Inhibition Zones ◽  
Probiotic Microorganism

The objectives of this investigation were a) to isolate bacteria from different foods (dairy products, fruits, and vegetables) and evaluate their probiotic potential and b) to select, identify, and characterize the strain with the highest probiotic potential. From 14 food samples, a total of 117 strains were isolated; however, only 42 (T1 to T42) showed the morphology (gram-positive, coco, and bacillar form) and were catalase- and oxidase-negative to be considered as a presumptive lactic acid bacteria (LAB). The antagonistic activity of the 42 strains was evaluated on Escherichia coli (O157:H7E09), Listeria monocytogenes (ATCC 19115), Staphylococcus aureus (ATCC 25923), and Salmonella enterica serotype Typhimurium (ATCC 14028). The strains with the highest antagonistic activity were nine isolates from the following: pulque (T1), sprouted beans (T26), ranchero cheese (T30, T31, T32, T33, T35, T36), and tenate cheese (T40) with inhibition zones from 17.0 ± 1.2 to 19.3 ± 2.8 mm. Based on the antagonistic activity against pathogenic bacteria and resistance to low pH and bile salts, strain T40 exhibited the highest probiotic potential. Using the 16S rRNA technique, strain T40 was identified as Lacticaseibacillus paracasei (the previous taxonomic nomenclature was Lactobacillus paracasei , prior to the nomenclature change in April 2020); this strain presented no resistance to ampicillin, gentamicin, erythromycin, and tetracycline. The antagonistic activity was evaluated in situ (fresh cheese) against pathogenic bacteria, evidencing the probiotic potential of L. paracasei . Finally, Lacticaseibacillus paracasei isolated from tenate cheese showed characteristics as a probiotic microorganism and high potential in food technology.

scholarly journals Identification of Quorum-Sensing Inhibitors Disrupting Signaling between Rgg and Short Hydrophobic Peptides in Streptococci

mBio ◽  
2015 ◽  
Vol 6 (3) ◽  
Author(s):  
Chaitanya Aggarwal ◽  
Juan Cristobal Jimenez ◽  
Hyun Lee ◽  
George E. Chlipala ◽  
Kiira Ratia ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Communication Networks ◽  
Drug Targets ◽  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Chemical Compounds ◽  
Content Type ◽  
Hydrophobic Peptides ◽  
Biofilm Development

ABSTRACTBacteria coordinate a variety of social behaviors, important for both environmental and pathogenic bacteria, through a process of intercellular chemical signaling known as quorum sensing (QS). As microbial resistance to antibiotics grows more common, a critical need has emerged to develop novel anti-infective therapies, such as an ability to attenuate bacterial pathogens by means of QS interference. Rgg quorum-sensing pathways, widespread in the phylumFirmicutes, employ cytoplasmic pheromone receptors (Rgg transcription factors) that directly bind and elicit gene expression responses to imported peptide signals. In the human-restricted pathogenStreptococcus pyogenes, the Rgg2/Rgg3 regulatory circuit controls biofilm development in response to the short hydrophobic peptides SHP2 and SHP3. Using Rgg-SHP as a model receptor-ligand target, we sought to identify chemical compounds that could specifically inhibit Rgg quorum-sensing circuits. Individual compounds from a diverse library of known drugs and drug-like molecules were screened for their ability to disrupt complexes of Rgg and FITC (fluorescein isothiocyanate)-conjugated SHP using a fluorescence polarization (FP) assay. The best hits were found to bind Rgg3in vitrowith submicromolar affinities, to specifically abolish transcription of Rgg2/3-controlled genes, and to prevent biofilm development inS. pyogeneswithout affecting bacterial growth. Furthermore, the top hit, cyclosporine A, as well as its nonimmunosuppressive analog, valspodar, inhibited Rgg-SHP pathways in multiple species ofStreptococcus. The Rgg-FITC-peptide-based screen provides a platform to identify inhibitors specific for each Rgg type. Discovery of Rgg inhibitors constitutes a step toward the goal of manipulating bacterial behavior for purposes of improving health.IMPORTANCEThe global emergence of antibiotic-resistant bacterial infections necessitates discovery not only of new antimicrobials but also of novel drug targets. Since antibiotics restrict microbial growth, strong selective pressures to develop resistance emerge quickly in bacteria. A new strategy to fight microbial infections has been proposed, namely, development of therapies that decrease pathogenicity of invading organisms while not directly inhibiting their growth, thus decreasing selective pressure to establish resistance. One possible means to this goal is to interfere with chemical communication networks used by bacteria to coordinate group behaviors, which can include the synchronized expression of genes that lead to disease. In this study, we identified chemical compounds that disrupt communication pathways regulated by Rgg proteins in species ofStreptococcus. Treatment of cultures ofS. pyogeneswith the inhibitors diminished the development of biofilms, demonstrating an ability to control bacterial behavior with chemicals that do not inhibit growth.

Significant immunomodulatory effects of Pseudomonas aeruginosa quorum-sensing signal molecules: possible link in human sepsis

2008 ◽  
Vol 115 (11) ◽  
pp. 343-351 ◽  
Author(s):  
Pisake Boontham ◽  
Adrian Robins ◽  
Palanichamy Chandran ◽  
David Pritchard ◽  
Miguel Cámara ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Dendritic Cell ◽  
Quorum Sensing ◽  
T Cell Activation ◽  
Pathogenic Bacteria ◽  
Interleukin 4 ◽  
Signal Molecules ◽  
Immunomodulatory Effects ◽  
The Impact

Pathogenic bacteria use quorum-sensing signal molecules to co-ordinate the expression of virulence genes. Animal-based studies have demonstrated the immunomodulatory effects of quorum-sensing signal molecules. In the present study, we have examined the impact of these molecules on normal human immune function in vitro and compared this with immune changes in patients with sepsis where quorum-sensing signal molecules were detected in the sera of patients. Quorum-sensing signal molecules inhibited normal dendritic cell and T-cell activation and proliferation, and down-regulated the expression of co-stimulatory molecules on dendritic cells; in MLDCRs (mixed lymphocyte dendritic cell reactions), secretion of IL (interleukin)-4 and IL-10 was enhanced, but TNF-α (tumour necrosis factor-α), IFN-γ (interferon-γ) and IL-6 was reduced. Quorum-sensing signal molecules induced apoptosis in dendritic cells and CD4+ cells, but not CD8+ cells. Dendritic cells from patients with sepsis were depleted and ex vivo showed defective expression of co-stimulatory molecules and dysfunctional stimulation of allogeneic T-lymphocytes. Enhanced apoptosis of dendritic cells and differential CD4+ Th1/Th2 (T-helper 1/2) cell apoptotic rate, and modified Th1/Th2 cell cytokine profiles in MLDCRs were also demonstrated in patients with sepsis. The pattern of immunological changes in patients with sepsis mirrors the effects of quorum-sensing signal molecules on responses of immune cells from normal individuals in vitro, suggesting that quorum-sensing signal molecules should be investigated further as a cause of immune dysfunction in sepsis.

scholarly journals The In Vitro Analysis of Prebiotics to Be Used as a Component of a Synbiotic Preparation

Nutrients ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1272 ◽  
Author(s):  
Katarzyna Śliżewska ◽  
Agnieszka Chlebicz-Wójcik
Keyword(s):  
Pathogenic Bacteria ◽  
Corn Starch ◽  
Health Benefit ◽  
Antagonistic Activity ◽  
Plate Count ◽  
Salmonella Spp ◽  
Probiotic Strains ◽  
The Impact ◽  
Lactobacillus Spp

Prebiotics are food components that are selectively fermented by beneficial microbiota and which confer a health benefit. The aim of the study was to select a prebiotic for the chosen probiotic strains to create a synbiotic. The impact of prebiotics (inulin, maltodextrin, corn starch, β-glucan, and apple pectin) on five Lactobacillus spp. strains’ growth and metabolites synthesis (lactic, acetic, propionic, and butyric acids, ethanol, and acetaldehyde) was tested by the plate count method and by high-performance liquid chromatography, respectively. Moreover, the differences in the ratio of D(−) and L(+) lactate isomers produced by Lactobacillus spp., as well as variations in the probiotics’ enzymatic profiles associated with the prebiotic used for cultivation, were determined with a Megazyme rapid assay kit and API® ZYM assay, accordingly. Finally, the influence of the carbon source (prebiotic) used on the antagonistic activity of the probiotic strains towards pathogenic bacteria, such as Salmonella spp. or Listeria monocytogenes was analyzed in the co-cultures. The results showed that the growth, metabolic profile, and antagonistic activity of the probiotics towards selected pathogens were the most favorable when 2% (w/v) of inulin was used. Therefore, the combination of inulin with selected probiotics is a promising synbiotic mixture.

In vitro evaluation of Bifidobacterium strains of human origin for potential use in probiotic functional foods

2013 ◽  
Vol 4 (2) ◽  
pp. 179-186 ◽  
Author(s):  
T.C. Souza ◽  
A.M. Silva ◽  
J.R.P. Drews ◽  
D.A. Gomes ◽  
C.G. Vinderola ◽  
...  
Keyword(s):  
Growth Rate ◽  
Cell Wall ◽  
Pathogenic Bacteria ◽  
Bifidobacterium Longum ◽  
Antagonistic Activity ◽  
Bifidobacterium Bifidum ◽  
In Vitro Tests ◽  
Healthy Children ◽  
Hydrophobic Property

The present study investigated some in vitro properties for probiotic use of four strains of bifidobacteria isolated from faeces of healthy children (Bifidobacterium longum 51A, Bifidobacterium breve 1101A, Bifidobacterium pseudolongum 1191A and Bifidobacterium bifidum 1622A). In vitro tests were carried out to compare growth rate, aerotolerance, antagonistic activity against pathogens, antimicrobial susceptibility profile and cell wall hydrophobicity. Mean doubling time of B. longum 51A was shorter compared to the other strains. All strains were aerotolerant up to 72 h of exposure to oxygen. In vitro antagonism showed that B. longum 51A and B. pseudolongum 1191A were able to produce inhibitory diffusible compounds against all pathogenic bacteria tested, but not against Candida albicans. B. longum 51A was sensitive to all the antimicrobials tested, except neomycin. The hydrophobic property of the cell wall was highest for B. bifidum 1622A. Based on these parameters, B. longum 51A showed the best potential for probiotic use among the tested strains, presenting the greatest sensitivity to antimicrobials, the best growth rate and the highest capacity to produce antagonistic substances against various pathogenic microorganisms.

scholarly journals In vivo microscopy reveals the impact ofPseudomonas aeruginosasocial interactions on host colonization

2018 ◽  
Author(s):  
Chiara Rezzoagli ◽  
Elisa T. Granato ◽  
Rolf Kümmerli
Keyword(s):  
Quorum Sensing ◽  
Social Interactions ◽  
Pathogenic Bacteria ◽  
Social Dynamics ◽  
Imaging System ◽  
Gut Colonization ◽  
Social Acts ◽  
The Impact

AbstractPathogenic bacteria engage in social interactions to colonize hosts, which include quorum-sensing-mediated communication and the secretion of virulence factors that can be shared as “public goods” between individuals. While in-vitro studies demonstrated that cooperative individuals can be displaced by “cheating” mutants freeriding on social acts, we know little about social interactions in infections. Here, we developed a live imaging system to track virulence factor expression and social strain interactions in the human pathogenPseudomonas aeruginosacolonizing the gut ofCaenorhabditis elegans. We found that shareable siderophores and quorum-sensing systems are expressed during infections, affect host gut colonization, and benefit nonproducers. However, non-producers were unable to cheat and outcompete producers, probably due to the spatial segregation of strains within the gut. Our results shed new light on bacterial social interactions in infections and reveal potential limits of therapeutic approaches that aim to capitalize on social dynamics between strains for infection control.

scholarly journals Inhibición del quórum sensing mediante el quórum quenching en postlarvas de Litopenaeus vannamei

2020 ◽  
pp. 01
Author(s):  
Jefferson Javier Intriago Angulo ◽  
Juan Gerardo Quimi Mujica ◽  
Jordana Jineyka López Parra ◽  
David Villarreal de la Torre ◽  
Edmundo Matute ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Litopenaeus Vannamei ◽  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Survival Rates ◽  
Quorum Quenching ◽  
Probiotic Bacteria ◽  
White Shrimp ◽  
In Vitro Tests

Inhibition of the quorum sensing by quorum quenching in postlarva of Litopenaeus vannamei El cultivo del camarón blanco Litopenaeus vannamei es un recurso acuícola de gran importancia económica a nivel mundial; sin embargo, es severamente afectado por varios tipos de enfermedades infecciosas, principalmente virales y bacterianas. Sin embargo las pérdidas masivas reportadas durante los últimos años, están generalmente relacionadas a infecciones bacterianas en particular, el síndrome de mortalidad temprana (EMS) y más recientemente relacionada a la enfermedad de necrosis hepatopancreática aguda (AHPND) por sus siglas en ingles. Para asegurar la sostenibilidad de la industria del camarón, se debe mejorar la productividad en particular mediante el uso de consorcios de bacterias probióticas eficientes para la prevención de las enfermedades bacterianas. Dos consorcios de bacterias probióticas (consorcios comerciales y consorcio CA), fueron evaluados en pruebas in vitro y en tanques de producción de post-larvas de camarón L. vannamei, donde se realizó la determinación subsecuente del grado de inhibición del quórum sensing de las bacterias patogénicas mediante el quórum quenching de bacterias probióticas y paralelamente a los análisis de sobrevivencia. Como resultados el consorcio CA fue el que presento mayor grado de inhibición del quorum sensing in vitro en paralelo a los mayores porcentajes de sobrevivencia en tanques de producción de post-larvas de camarón. El mejor efecto probiótico en post-larvas de L. vannamei resultaron en los tratamientos del consorcio CA, como los mejores supresores en la presencia de vibrios en el cultivo bacteriológico así como mayores porcentajes de sobrevivencia en tanques de producción de post-larvas de camarón. Palabras clave: Litopenaeus vannamei; quorum sensing; quorum quenching; bacterias patogénicas; bacterias probióticas Abstract The cultivation of white shrimp Litopenaeus vannamei is an aquaculture resource of great economic importance worldwide; however, it is severely affected by several types of infectious diseases, mainly viral and bacterial. However, the massive losses reported in recent years are generally related to bacterial infections in particular, early mortality syndrome (EMS) and more recently related to acute hepatopancreatic necrosis disease (AHPND). To ensure the sustainability of the shrimp industry, productivity must be improved in particular by the use of efficient probiotic bacteria consortia for the prevention of bacterial diseases. Two consortia of probiotic bacteria (commercial consortia and CA consortium) were evaluated in in vitro tests and in post-larvae production tanks of L. vannamei shrimp, where the subsequent determination of the degree of inhibition of the quorum sensing of pathogenic bacteria was carried out. By the quenching quorum of probiotic bacteria and parallel to the survival analysis. As a result, the CA consortium showed the greatest degree of inhibition of in vitro quorum sensing in parallel to the higher survival rates in shrimp post-larval production tanks. The best probiotic effect in post-larvae of L. vannamei resulted in the CA consortia treatments, as the best suppressors in the presence of vibrios in the bacteriological culture as well as higher survival rates in post-larvae shrimp production tanks Keywords: Litopenaeus vannamei; quorum sensing; quorum quenching; pathogenic bacteria; probiotic bacteria.

scholarly journals THE IDENTIFICATION, PRODUCTION AND CHARACTERIZATION OF NATTOKINASE, BACTERIOCIN FROM BACTERIAL SPECIES

2019 ◽  
Vol 2 (4) ◽  
pp. 91
Author(s):  
Lal Krishna
Keyword(s):  
Enzyme Activity ◽  
Bacillus Subtilis ◽  
Pathogenic Bacteria ◽  
Blood Clot ◽  
Bacterial Species ◽  
Antagonistic Activity ◽  
Bacterial Strains ◽  
Wide Range

The study was aimed at identification, production and characterization of nattokinase, bacteriocin from bacterial species. Nattokinase and bacteriocins finds a wide range of applications in Pharmaceutical industry, health care and medicine. Nattokinase is a highly active fibrinolytic enzyme secreted by Bacillus subtilis and bacteriocins are proteinaceous toxins produced by Lactobacillus to inhibit the growth of closely related bacterial strains. Bacillus subtilis and Lactobacillus isolates shown positive results to microscopic, biochemical analysis.  The nattokinase and bacteriocins were produced by optimizing the media. The enzymes were purified by ammonium sulfate precipitation and HPLC. The enzyme activity for nattokinase was found at 7 mg/ml, pH 8.0 and temperature 48 ºC and the enzyme activity for bacteriocin was found at 3.9 mg/ml, pH 6.5 and temperature 30 °C. Bacteriocins from Lactobacillus showed good antagonistic activity against pathogenic bacteria. Nattokinase from Bacillus subtilis played a significant role in thrombolytic and anti-coagulation at in vitro. The results indicated that the pure enzyme has a potential in dissolving blood clot.

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