scholarly journals Gene Analysis of Listeria monocytogenes Suspended Aggregates Induced by Ralstonia insidiosa Cell-Free Supernatants under Nutrient-Poor Environments

2021 ◽  
Vol 9 (12) ◽  
pp. 2591
Author(s):  
Qun Li ◽  
Ailing Guo ◽  
Yi Ma ◽  
Ling Liu ◽  
Wukang Liu ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Rna Sequencing ◽  
Pathogenic Bacteria ◽  
Bacterial Chemotaxis ◽  
Reaction Network ◽  
Two Component System ◽  
Food Borne ◽  
Flagellar Assembly ◽  
New Perspective ◽  
Ralstonia Insidiosa

Listeria monocytogenes is a zoonotic food-borne pathogen. The production of food-borne pathogenic bacteria aggregates is considered to be a way to improve their resistance and persistence in the food chain. Ralstonia insidiosa has been shown to induce L. monocytogenes to form suspended aggregates, but induction mechanisms remain unclear. In the study, the effect of R. insidiosa cell-free supernatants cultured in 10% TSB medium (10% RIS) on the formation of L. monocytogenes suspended aggregates was evaluated. Next, the Illumina RNA sequencing was used to compare the transcriptional profiles of L. monocytogenes in 10% TSB medium with and without 10% RIS to identify differentially expressed genes (DEGs). The result of functional annotation analysis of DEGs indicated that these genes mainly participate in two component system, bacterial chemotaxis and flagellar assembly. Then the reaction network of L. monocytogenes suspended aggregates with the presence of 10% RIS was summarized. The gene-deletion strain of L. monocytogenes was constructed by homologous recombination. The result showed that cheA and cheY are key genes in the formation of suspended aggregates. This research is the preliminary verification of suspended aggregates’ RNA sequencing and is helpful to analyze the aggregation mechanisms of food-borne pathogenic bacteria from a new perspective.

scholarly journals A Rapid and Sensitive Europium Nanoparticle-Based Lateral Flow Immunoassay Combined with Recombinase Polymerase Amplification for Simultaneous Detection of Three Food-Borne Pathogens

2021 ◽  
Vol 18 (9) ◽  
pp. 4574
Author(s):  
Kai Chen ◽  
Biao Ma ◽  
Jiali Li ◽  
Erjing Chen ◽  
Ying Xu ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Vibrio Parahaemolyticus ◽  
Pathogenic Bacteria ◽  
Simultaneous Detection ◽  
Lateral Flow ◽  
Recombinase Polymerase Amplification ◽  
Quantitative Detection ◽  
Bacterial Strains ◽  
Food Borne Pathogens ◽  
Food Borne

Food-borne pathogens have become an important public threat to human health. There are many kinds of pathogenic bacteria in food consumed daily. A rapid and sensitive testing method for multiple food-borne pathogens is essential. Europium nanoparticles (EuNPs) are used as fluorescent probes in lateral flow immunoassays (LFIAs) to improve sensitivity. Here, recombinase polymerase amplification (RPA) combined with fluorescent LFIA was established for the simultaneous and quantitative detection of Listeria monocytogenes, Vibrio parahaemolyticus, and Escherichia coliO157:H7. In this work, the entire experimental process could be completed in 20 min at 37 °C. The limits of detection (LODs) of EuNP-based LFIA–RPA were 9.0 colony-forming units (CFU)/mL for Listeria monocytogenes, 7.0 CFU/mL for Vibrio parahaemolyticus, and 4.0 CFU/mL for Escherichia coliO157:H7. No cross-reaction could be observed in 22 bacterial strains. The fluorescent LFIA–RPA assay exhibits high sensitivity and good specificity. Moreover, the average recovery of the three food-borne pathogens spiked in food samples was 90.9–114.2%. The experiments indicate the accuracy and reliability of the multiple fluorescent test strips. Our developed EuNP-based LFIA–RPA assay is a promising analytical tool for the rapid and simultaneous detection of multiple low concentrations of food-borne pathogens.

scholarly journals Identification of the agr Locus of Listeria monocytogenes: Role in Bacterial Virulence

2003 ◽  
Vol 71 (8) ◽  
pp. 4463-4471 ◽  
Author(s):  
Nicolas Autret ◽  
Catherine Raynaud ◽  
Iharilalao Dubail ◽  
Patrick Berche ◽  
Alain Charbit
Keyword(s):  
Listeria Monocytogenes ◽  
Response Regulator ◽  
Lethal Dose ◽  
Fold Increase ◽  
Bacterial Virulence ◽  
Intravenous Route ◽  
Two Component System ◽  
Food Borne ◽  
Severe Infections

ABSTRACT Listeria monocytogenes is a gram-positive facultative intracellular food-borne pathogen that can cause severe infections in humans and animals. We have recently adapted signature-tagged transposon mutagenesis (STM) to identify genes involved in the virulence of L. monocytogenes. A new round of STM allowed us to identify a new locus encoding a protein homologous to AgrA, the well-studied response regulator of Staphylococcus aureus and part of a two-component system involved in bacterial virulence. The production of several secreted proteins was modified in the agrA mutant of L. monocytogenes grown in broth, indicating that the agr locus influenced protein secretion. Inactivation of agrA did not affect the ability of the pathogen to invade and multiply in cells in vitro. However, the virulence of the agrA mutant was attenuated in the mouse (a 10-fold increase in the 50% lethal dose by the intravenous route), demonstrating for the first time a role for the agr locus in the virulence of L. monocytogenes.

Establishment of Multiple-PCR for Diagnosing Three Food-Borne Pathogenic Bacteria in Aquatic Products

2012 ◽  
Vol 554-556 ◽  
pp. 1029-1032
Author(s):  
Hui Li Xia ◽  
Hui Zheng ◽  
Jin Jun Zhang
Keyword(s):  
Listeria Monocytogenes ◽  
Multiplex Pcr ◽  
Vibrio Parahaemolyticus ◽  
Pathogenic Bacteria ◽  
Pcr Amplification ◽  
National Standard ◽  
Aquatic Products ◽  
Gene Coding ◽  
Food Borne ◽  
Pcr Method

A rapid multiplex-PCR method was established in order to detect three foodborne pathogenic bacteria including Salmonella typli，Vibrio parahaemolyticus and Listeria monocytogenes in aquatic products. Three pairs of oligonucleotide primers were designed for multiplex-PCR amplification according to gene coding invasion protein A of Salmonella typli，gene coding immune response of Vibrio parahaemolyticus and regulation histone gene of Listeria monocytogenes. The amplified fragment sizes of these three bacteria were 213 bp, 369 bp and 517bp, respectively．The specificity of the multiplex- PCR was high and the minimum detection limit reached 103 CFU/mL. The multiplex-PCR method was used to analyze three aquatic product samples compared with national standard methods, the coincidence rate of two methods reached 100%. The method developed in this study had high sensitivity and specificity, which could be applied for the rapid detection and molecular epidemiology survey of food-borne pathogenic bacteria in aquatic products．

scholarly journals Antimicrobial Effects of Mustard Flour and Acetic Acid against Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica Serovar Typhimurium

2003 ◽  
Vol 69 (5) ◽  
pp. 2959-2963 ◽  
Author(s):  
Min-Suk Rhee ◽  
Sun-Young Lee ◽  
Richard H. Dougherty ◽  
Dong-Hyun Kang
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Bacterial Resistance ◽  
Fixed Amount ◽  
E Coli ◽  
Food Borne ◽  
Serovar Typhimurium

ABSTRACT This study was designed to investigate the individual and combined effects of mustard flour and acetic acid in the inactivation of food-borne pathogenic bacteria stored at 5 and 22°C. Samples were prepared to achieve various concentrations by the addition of acetic acid (0, 0.5, or 1%) along with mustard flour (0, 10, or 20%) and 2% sodium chloride (fixed amount). Acid-adapted three-strain mixtures of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica serovar Typhimurium strains (106 to 107 CFU/ml) were inoculated separately into prepared mustard samples stored at 5 and 22°C, and samples were assayed periodically. The order of bacterial resistance, assessed by the time required for the nominated populations to be reduced to undetectable levels against prepared mustards at 5°C, was S. enterica serovar Typhimurium (1 day) < E. coli O157:H7 (3 days) < L. monocytogenes (9 days). The food-borne pathogens tested were reduced much more rapidly at 22°C than at 5°C. There was no synergistic effect with regard to the killing of the pathogens tested with the addition of 0.5% acetic acid to the mustard flour (10 or 20%). Mustard in combination with 0.5% acetic acid had less bactericidal activity against the pathogens tested than did mustard alone. The reduction of E. coli O157:H7 and L. monocytogenes among the combined treatments on the same storage day was generally differentiated as follows: control < mustard in combination with 0.5% acetic acid < mustard alone < mustard in combination with 1% acetic acid < acetic acid alone. Our study indicates that acidic products may limit microbial growth or survival and that the addition of small amounts of acetic acid (0.5%) to mustard can retard the reduction of E. coli O157:H7 and L. monocytogenes. These antagonistic effects may be changed if mustard is used alone or in combination with >1% acetic acid.

scholarly journals Inhibition of Listeria monocytogenes by Food-Borne Yeasts

2006 ◽  
Vol 72 (1) ◽  
pp. 313-318 ◽  
Author(s):  
Stefanie Goerges ◽  
Ulrike Aigner ◽  
Barbara Silakowski ◽  
Siegfried Scherer
Keyword(s):  
Listeria Monocytogenes ◽  
Pathogenic Bacteria ◽  
Soft Agar ◽  
Cell Contact ◽  
Screening Assay ◽  
Food Borne ◽  
Low Degree ◽  
Inhibitory Molecule ◽  
Direct Cell ◽  
Inhibitory Potential

ABSTRACT Many bacteria are known to inhibit food pathogens, such as Listeria monocytogenes, by secreting a variety of bactericidal and bacteriostatic substances. In sharp contrast, it is unknown whether yeast has an inhibitory potential for the growth of pathogenic bacteria in food. A total of 404 yeasts were screened for inhibitory activity against five Listeria monocytogenes strains. Three hundred and four of these yeasts were isolated from smear-ripened cheeses. Most of the yeasts were identified by Fourier transform infrared spectroscopy. Using an agar-membrane screening assay, a fraction of approximately 4% of the 304 red smear cheese isolates clearly inhibited growth of L. monocytogenes. Furthermore, 14 out of these 304 cheese yeasts were cocultivated with L. monocytogenes WSLC 1364 on solid medium to test the antilisterial activity of yeast in direct cell contact with Listeria. All yeasts inhibited L. monocytogenes to a low degree, which is most probably due to competition for nutrients. However, one Candida intermedia strain was able to reduce the listerial cell count by 4 log units. Another four yeasts, assigned to C. intermedia (three strains) and Kluyveromyces marxianus (one strain), repressed growth of L. monocytogenes by 3 log units. Inhibition of L. monocytogenes was clearly pronounced in the cocultivation assay, which simulates the conditions and contamination rates present on smear cheese surfaces. We found no evidence that the unknown inhibitory molecule is able to diffuse through soft agar.

Biofilm Formation and Associated Genes in Listeria Monocytogenes

2017 ◽  
Vol 12 (3) ◽  
Author(s):  
S. R. Warke ◽  
V. C. Ingle ◽  
N. V. Kurkure ◽  
P. A. Tembhurne ◽  
Minakshi Prasad ◽  
...  
Keyword(s):  
Public Health ◽  
Listeria Monocytogenes ◽  
Multiplex Pcr ◽  
Food Processing ◽  
Biofilm Formation ◽  
Milk Samples ◽  
Biofilm Production ◽  
Food Borne ◽  
Serious Infections ◽  
Microtiter Assay

Listeria monocytogenes, an opportunistic food borne pathogen can cause serious infections in immunocompromised individuals. L. monocytogenes is capable of producing biofilm on the surface of food processing lines and instruments.The biofilm transfers contamination to food products and impose risk to public health. In the present study biofilm producing ability of L. monocytogenes isolates were investigated phenotypically and genotypically by microtiter assay and multiplex PCR, respectively. Out of 38 L. monocytogenes isolates 14 were recovered from animal clinical cases, 12 bovine environment and 12 from milk samples. A total of 3 (21.42%) clinical, 2 (16.66%) environment and 3 (25%) milk samples respectively, revealed biofilm production in microtiter assay. Cumulative results showed that 23 (60.52%) out of 38 strains of L. monocytogenes were positive for luxS and flaA gene and 1 (2.63%) was positive only for the flaA gene.

scholarly journals Effect of Gaseous Ozone on Listeria monocytogenes Planktonic Cells and Biofilm: An In Vitro Study

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1484
Author(s):  
Felice Panebianco ◽  
Selene Rubiola ◽  
Francesco Chiesa ◽  
Tiziana Civera ◽  
Pierluigi Aldo Di Ciccio
Keyword(s):  
Listeria Monocytogenes ◽  
In Vitro Study ◽  
Planktonic Cells ◽  
Free Living ◽  
Biofilm Inhibition ◽  
Additional Tool ◽  
Complete Inactivation ◽  
Gaseous Ozone ◽  
Food Borne

Among food-borne pathogens, Listeria monocytogenes continues to pose concerns to food business operators due to its capacity to form biofilm in processing environments. Ozone may be an eco-friendly technology to control microbial contaminations, but data concerning its effect on Listeria monocytogenes biofilm are still limited. In this study, the effect of gaseous ozone at 50 ppm on planktonic cells and biofilm of reference and food-related Listeria monocytogenes strains was evaluated. Ozone caused a reduction in microbial loads of 3.7 ± 0.4 and 3.9 ± 0.4 Log10 CFU/mL after 10 and 30 min, respectively. A complete inactivation of planktonic cells after 6 h of treatment was observed. Biofilm inhibition and eradication treatments (50 ppm, 6 h) resulted in a significant decrease of the biofilm biomass for 59% of the strains tested, whilst a slight dampening of live cell loads in the biofilm state was observed. In conclusion, gaseous ozone is not sufficient to completely counteract Listeria monocytogenes biofilm, but it may be useful as an additional tool to contrast Listeria monocytogenes free-living cells and to improve the existing sanitization procedures in food processing environments.

scholarly journals Transcriptome Analysis of the Cecal Tonsil of Jingxing Yellow Chickens Revealed the Mechanism of Differential Resistance to Salmonella

Genes ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 979 ◽  
Author(s):  
Fei Wang ◽  
Jin Zhang ◽  
Bo Zhu ◽  
Jie Wang ◽  
Qiao Wang ◽  
...  
Keyword(s):  
Immune Response ◽  
Pathogenic Bacteria ◽  
Molecular Mechanisms ◽  
Differential Resistance ◽  
Receptor Interaction ◽  
Salmonella Infection ◽  
Poultry Products ◽  
Food Borne ◽  
Cecal Tonsil ◽  
Iga Production

Salmonella is one of the most common food-borne pathogens. It can be transmitted between chickens, as well as to people by contaminated poultry products. In our study, we distinguished chickens with different resistances mainly based on bacterial loads. We compared the cecal tonsil transcriptomes between the susceptible and resistant chickens after Salmonella infection, aiming to identify the crucial genes participating in the antibacterial activity in the cecal tonsil. A total of 3214 differentially expressed genes (DEGs), including 2092 upregulated and 1122 downregulated genes, were identified between the two groups (fold change ≥ 2.0, padj < 0.05). Many DEGs were mainly involved in the regulation of two biological processes: crosstalk between the cecal tonsil epithelium and pathogenic bacteria, such as focal adhesion, extracellular-matrix–receptor interaction, and regulation of the actin cytoskeleton and host immune response including the cytokine–receptor interaction. In particular, the challenged resistant birds exhibited strong activation of the intestinal immune network for IgA production, which perhaps contributed to the resistance to Salmonella infection. These findings give insight into the mRNA profile of the cecal tonsil between the two groups after initial Salmonella stimulation, which may extend the known complexity of molecular mechanisms in chicken immune response to Salmonella.

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