β-Phenylethylamine as a Natural Food Additive Shows Antimicrobial Activity against Listeria monocytogenes on Ready-to-Eat Foods

Listeria monocytogenes is an important foodborne pathogen and a major cause of death associated with bacterial foodborne infections. Control of L. monocytogenes on most ready-to-eat (RTE) foods remains a challenge. The potential use of β-phenylethylamine (PEA) as an organic antimicrobial against L. monocytogenes was evaluated in an effort to develop a new intervention for its control. Using a collection of 62 clinical and food-related isolates we determined the minimum inhibitory concentration (MIC) of PEA against L. monocytogenes in different broth and agar media. Bologna type sausage (lyoner) and smoked salmon were used as food model systems to validate the in vitro findings. PEA had a growth inhibitory and bactericidal effect against L. monocytogenes both in in vitro experiments as well as on lyoner and smoked salmon. The MIC’s ranged from 8 to 12.5 mg/mL. Furthermore, PEA also inhibited L. monocytogenes biofilm formation. Based on good manufacturing practices as a prerequisite, the application of PEA to RTE products might be an additional hurdle to limit L. monocytogenes growth thereby increasing food safety.

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Natural Plant-Derived Chemical Compounds as Listeria monocytogenes Inhibitors In Vitro and in Food Model Systems

Pathogens ◽

10.3390/pathogens10010012 ◽

2020 ◽

Vol 10 (1) ◽

pp. 12

Author(s):

Iwona Kawacka ◽

Agnieszka Olejnik-Schmidt ◽

Marcin Schmidt ◽

Anna Sip

Keyword(s):

Listeria Monocytogenes ◽

Foodborne Pathogen ◽

Chemical Compounds ◽

Food Product ◽

Model Systems ◽

Biofilm Inhibition ◽

Natural Plant ◽

Alternative Delivery ◽

Food Model

Listeria monocytogenes is a foodborne pathogen, sporadically present in various food product groups. An illness caused by the pathogen, named listeriosis, has high fatality rates. Even though L. monocytogenes is resistant to many environmental factors, e.g., low temperatures, low pH and high salinity, it is susceptible to various natural plant-derived antimicrobials (NPDA), including thymol, carvacrol, eugenol, trans-cinnamaldehyde, carvone S, linalool, citral, (E)-2-hexenal and many others. This review focuses on identifying NPDAs active against L. monocytogenes and their mechanisms of action against the pathogen, as well as on studies that showed antimicrobial action of the compounds against the pathogen in food model systems. Synergistic action of NDPA with other factors, biofilm inhibition and alternative delivery systems (encapsulation and active films) of the compounds tested against L. monocytogenes are also summarized briefly.

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Lmo0036, an ornithine and putrescine carbamoyltransferase in Listeria monocytogenes, participates in arginine deiminase and agmatine deiminase pathways and mediates acid tolerance

Microbiology ◽

10.1099/mic.0.049619-0 ◽

2011 ◽

Vol 157 (11) ◽

pp. 3150-3161 ◽

Cited By ~ 38

Author(s):

Jianshun Chen ◽

Changyong Cheng ◽

Ye Xia ◽

Hanxin Zhao ◽

Chun Fang ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Foodborne Pathogens ◽

Foodborne Pathogen ◽

Acid Tolerance ◽

Arginine Deiminase ◽

Transcriptional Level ◽

Acidic Conditions ◽

Acidic Environments ◽

Agmatine Deiminase

Listeria monocytogenes is a foodborne pathogen causing listeriosis. Acid is one of the stresses that foodborne pathogens encounter most frequently. The ability to survive and proliferate in acidic environments is a prerequisite for infection. However, there is limited knowledge about the molecular basis of adaptation of L. monocytogenes to acid. Arginine deiminase (ADI) and agmatine deiminase (AgDI) systems are implicated in bacterial tolerance to acidic environments. Homologues of ADI and AgDI systems have been found in L. monocytogenes lineages I and II strains. Sequence analysis indicated that lmo0036 encodes a putative carbamoyltransferase containing conserved motifs and residues important for substrate binding. Lmo0036 acted as an ornithine carbamoyltransferase and putrescine carbamoyltransferase, representing the first example, to our knowledge, that catalyses reversible ornithine and putrescine carbamoyltransfer reactions. Catabolic ornithine and putrescine carbamoyltransfer reactions constitute the second step of ADI and AgDI pathways. However, the equilibrium of in vitro carbamoyltransfer reactions was overwhelmingly towards the anabolic direction, suggesting that catabolic carbamoyltransferase was probably the limiting step of the pathways. lmo0036 was induced at the transcriptional level when L. monocytogenes was subjected to low-pH stress. Its expression product in Escherichia coli exhibited higher catabolic carbamoyltransfer activities under acidic conditions. Consistently, absence of this enzyme impaired the growth of Listeria under mild acidic conditions (pH 4.8) and reduced its survival in synthetic human gastric fluid (pH 2.5), and corresponded to a loss in ammonia production, indicating that Lmo0036 was responsible for acid tolerance at both sublethal and lethal pH levels. Furthermore, Lmo0036 played a possible role in Listeria virulence.

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Mutant and Recombinant Phages Selected from In Vitro Coevolution Conditions Overcome Phage-Resistant Listeria monocytogenes

Applied and Environmental Microbiology ◽

10.1128/aem.02138-20 ◽

2020 ◽

Vol 86 (22) ◽

Cited By ~ 1

Author(s):

Tracey Lee Peters ◽

Yaxiong Song ◽

Daniel W. Bryan ◽

Lauren K. Hudson ◽

Thomas G. Denes

Keyword(s):

Listeria Monocytogenes ◽

Host Range ◽

Foodborne Pathogen ◽

Resistant Bacteria ◽

Phage Resistance ◽

Short Term ◽

Content Type ◽

Life Threatening ◽

The Impact

ABSTRACT Bacteriophages (phages) are currently available for use by the food industry to control the foodborne pathogen Listeria monocytogenes. Although phage biocontrols are effective under specific conditions, their use can select for phage-resistant bacteria that repopulate phage-treated environments. Here, we performed short-term coevolution experiments to investigate the impact of single phages and a two-phage cocktail on the regrowth of phage-resistant L. monocytogenes and the adaptation of the phages to overcome this resistance. We used whole-genome sequencing to identify mutations in the target host that confer phage resistance and in the phages that alter host range. We found that infections with Listeria phages LP-048, LP-125, or a combination of both select for different populations of phage-resistant L. monocytogenes bacteria with different regrowth times. Phages isolated from the end of the coevolution experiments were found to have gained the ability to infect phage-resistant mutants of L. monocytogenes and L. monocytogenes strains previously found to be broadly resistant to phage infection. Phages isolated from coinfected cultures were identified as recombinants of LP-048 and LP-125. Interestingly, recombination events occurred twice independently in a locus encoding two proteins putatively involved in DNA binding. We show that short-term coevolution of phages and their hosts can be utilized to obtain mutant and recombinant phages with adapted host ranges. These laboratory-evolved phages may be useful for limiting the emergence of phage resistance and for targeting strains that show general resistance to wild-type (WT) phages. IMPORTANCE Listeria monocytogenes is a life-threatening bacterial foodborne pathogen that can persist in food processing facilities for years. Phages can be used to control L. monocytogenes in food production, but phage-resistant bacterial subpopulations can regrow in phage-treated environments. Coevolution experiments were conducted on a Listeria phage-host system to provide insight into the genetic variation that emerges in both the phage and bacterial host under reciprocal selective pressure. As expected, mutations were identified in both phage and host, but additionally, recombination events were shown to have repeatedly occurred between closely related phages that coinfected L. monocytogenes. This study demonstrates that in vitro evolution of phages can be utilized to expand the host range and improve the long-term efficacy of phage-based control of L. monocytogenes. This approach may also be applied to other phage-host systems for applications in biocontrol, detection, and phage therapy.

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Growth Potential of Listeria monocytogenes in Three Different Salmon Products

Foods ◽

10.3390/foods9081048 ◽

2020 ◽

Vol 9 (8) ◽

pp. 1048 ◽

Cited By ~ 2

Author(s):

Corinne Eicher ◽

Andres Ruiz Subira ◽

Sabrina Corti ◽

Arnulf Meusburger ◽

Roger Stephan ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Challenge Test ◽

High Growth ◽

Growth Potential ◽

High Concentration ◽

Food Borne ◽

Smoked Salmon ◽

Good Manufacturing Practices ◽

Challenge Tests ◽

Low Levels

Cold smoked salmon and sushi salmon have been implicated in outbreaks of listeriosis. We performed challenge tests and a durability study with Listeria monocytogenes on different salmon products to determine the growth potential of this important food-borne pathogen. Data from the challenge test showed a significant growth potential of L. monocytogenes on all of the tested salmon products, with faster growth in sushi salmon than in cold smoked salmon. In identical products that were naturally contaminated at low levels, the durability study did not confirm a high growth potential, possibly due to interactions with competing microflora. The injection of sodium lactate (NaL) at a high concentration (30%) into cold smoked salmon significantly reduced the growth potential of L. monocytogenes. In addition to good manufacturing practices, the injection of higher concentrations of NaL may therefore be a useful additional hurdle to prevent growth of L. monocytogenes to high numbers in the tested salmon products.

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Antilisterial Activity of a Carnobacterium piscicola Isolated from Brazilian Smoked Fish (Surubim [Pseudoplatystoma sp.]) and Its Activity against a Persistent Strain of Listeria monocytogenes Isolated from Surubim

Journal of Food Protection ◽

10.4315/0362-028x-68.10.2068 ◽

2005 ◽

Vol 68 (10) ◽

pp. 2068-2077 ◽

Cited By ~ 20

Author(s):

VIRGÍNIA F. ALVES ◽

ELAINE C. P. DE MARTINIS ◽

MARIA TERESA DESTRO ◽

BIRTE FONNESBECH VOGEL ◽

LONE GRAM

Keyword(s):

Listeria Monocytogenes ◽

Freshwater Fish ◽

Random Amplified Polymorphic Dna ◽

Model Systems ◽

Fish Products ◽

Tropical Regions ◽

Smoked Fish ◽

Smoked Salmon ◽

Carnobacterium Piscicola

Data on the prevalence and growth of Listeria monocytogenes in lightly preserved fish products from subtropical and tropical regions are very scarce. Our research describes L. monocytogenes that was detected in 5% of the packages of cold-smoked surubim, a native Brazilian freshwater fish that we analyzed, and shows that the strains isolated were of the same random amplified polymorphic DNA subtype as the strains that were isolated from the same factory 4 years earlier. A bacteriocinogenic strain of Carnobacterium piscicola (strain C2), isolated from vacuum-packed cold-smoked surubim, and two C. piscicola strains, isolated from vacuum-packed, cold-smoked salmon, were capable of limiting or completely inhibiting the growth of an L. monocytogenes (strain V2) isolated from surubim in fish peptone model systems incubated at 10°C. Mono-cultures of L. monocytogenes reached 108 CFU/ml (g), whereas the growth of L. monocytogenes was completely inhibited by C. piscicola C2. The bacteriocinogenic C. piscicola A9b+ and its nonbacteriocinogenic mutant A9b− reduced maximum Listeria levels by 2 to 3 log units. Both bacteriocinogenic C. piscicola strains prevented listerial growth in cold-smoked fish juices (surubim and salmon). Although the carnobacteria grew poorly on cold-smoked surubim at 10°C, the strains were able to reduce maximum Listeria counts by 1 to 3 log units in an artificially inoculated product (surubim). We conclude that Brazilian smoked fish products harbor L. monocytogenes and should be stabilized against the growth of the organism. C. piscicola C2 has the potential for use as a bioprotective culture in surubim and other lightly preserved fish, but further studies are required to optimize its effect.

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Low Prevalence of Listeria monocytogenes in Foods from Italy

Journal of Food Protection ◽

10.4315/0362-028x-70.6.1507 ◽

2007 ◽

Vol 70 (6) ◽

pp. 1507-1512 ◽

Cited By ~ 30

Author(s):

L. LATORRE ◽

A. PARISI ◽

R. FRACCALVIERI ◽

G. NORMANNO ◽

M. C. NARDELLA LA PORTA ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Foodborne Pathogen ◽

Poultry Meat ◽

Animal Origin ◽

Smoked Salmon ◽

Hygienic Measures ◽

Seafood Products ◽

Common Serotypes ◽

Meat Samples ◽

Low Prevalence

Listeria monocytogenes is an important foodborne pathogen that causes gastrointestinal disorders, and, especially in immunocompromised people, serious extraintestinal diseases, such as septicemia and meningitis, as well as abortion in pregnant women. Many foods, from both plant and animal origin, have been involved in listeriosis outbreaks. This article reports the results of a 12-year survey (1993 through 2004) on the presence of L. monocytogenes in several kinds of food marketed in Italy. Of 5,788 analyzed samples, 121 (2.1%) were contaminated with L. monocytogenes. The highest prevalence was found in smoked salmon (10.6%) and in poultry meat samples (8.5%) and the lowest in red meat (0.3%). L. monocytogenes was not found in 154 samples of fresh seafood products. Fifty-two isolates were also serotyped by the agglutination method. The most common serotypes detected in the 52 strains tested were 1/2a (36.5%), followed by 1/2c (32.8%), 1/2b (13.5%), 4b (11.5%), 3a (3.8%), and 3b (1.9%). The results of the present study showed low levels of L. monocytogenes in the analyzed samples. A total of 61.5% of the 52 L. monocytogenes strains analyzed belonged to serotypes 1/2a, 1/2b, and 4b, namely the serovars that are most commonly involved in extraintestinal human listeriosis outbreaks. In the ready-to-eat samples, these three serotypes were 40.0% (1/2a), 17.1% (1/2b), and 14.3% (4b). This finding highlights the need to implement strict hygienic measures during the production, distribution, and sale of foods to reduce the risk of foodborne listeriosis in humans to an acceptable level.

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Analysis of genetic diversity and antibiotic options for clinical Listeria monocytogenes infections in China

Open Forum Infectious Diseases ◽

10.1093/ofid/ofab177 ◽

2021 ◽

Author(s):

Wei Yu ◽

Yicheng Huang ◽

Chaoqun Ying ◽

Yanzi Zhou ◽

Li Zhang ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Biofilm Formation ◽

Virulence Genes ◽

Genomic Island ◽

Therapeutic Option ◽

Treatment Options ◽

Bactericidal Effect ◽

Time Kill ◽

Sequence Types

Abstract Background The aim of this study was to investigate the mechanism of Listeria monocytogenes (Lm) pathogenicity and resistance. In addition, the effect of existing treatment options against Lm were systematically evaluated. Methods Six Lm isolates were collected and antimicrobial susceptibility testing of 15 antibiotics were done. Subsequently, whole genome sequencing and bioinformatics analysis were performed. Biofilm formation was evaluated by crystal violet staining. Furthermore, the effect of meropenem, linezolid, penicillin, vancomycin, trimethoprim/sulfamethoxazole were determined using the time-kill assay. Results Four sequence types (STs) were identified (ST1, ST3, ST87, ST451). Multi-virulence-locus sequence typing (MVLST) results classified ST87 isolates into cluster. All isolates were resistant to fosfomycin and daptomycin with fosX and mprF. In addition, a total of 80 virulence genes were detected and 72 genes were found in all six isolates. Seven genes associated with haemolysin were found in 26530 and 115423. However, due to lack of one genomic island including virulence genes related to flagellar synthesis, isolate 115423 produced less biofilm than five other isolates. Even all isolates were susceptible to vancomycin, the in vitro time-kill assay showed vancomycin monotherapy resulted in less than 2 log10 CFU/mL compared with the initial count. Trimethoprim/sulfamethoxazole at serum or cerebrospinal fluid concentrations had bactericidal effect against tested Lm strains at 24 h. Conclusions ST87 clone was a typical prevalent ST in clinical Lm isolates in China. Trimethoprim/sulfamethoxazole might be greater potential therapeutic option against Lm infections.

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Commensal microbes provide first line defense against Listeria monocytogenes infection

Journal of Experimental Medicine ◽

10.1084/jem.20170495 ◽

2017 ◽

Vol 214 (7) ◽

pp. 1973-1989 ◽

Cited By ~ 71

Author(s):

Simone Becattini ◽

Eric R. Littmann ◽

Rebecca A. Carter ◽

Sohn G. Kim ◽

Sejal M. Morjaria ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Intestinal Microbiota ◽

Systemic Disease ◽

Foodborne Pathogen ◽

Antibiotic Administration ◽

Defensive Role ◽

Listeria Monocytogenes Infection ◽

Dose Oral

Listeria monocytogenes is a foodborne pathogen that causes septicemia, meningitis and chorioamnionitis and is associated with high mortality. Immunocompetent humans and animals, however, can tolerate high doses of L. monocytogenes without developing systemic disease. The intestinal microbiota provides colonization resistance against many orally acquired pathogens, and antibiotic-mediated depletion of the microbiota reduces host resistance to infection. Here we show that a diverse microbiota markedly reduces Listeria monocytogenes colonization of the gut lumen and prevents systemic dissemination. Antibiotic administration to mice before low dose oral inoculation increases L. monocytogenes growth in the intestine. In immunodeficient or chemotherapy-treated mice, the intestinal microbiota provides nonredundant defense against lethal, disseminated infection. We have assembled a consortium of commensal bacteria belonging to the Clostridiales order, which exerts in vitro antilisterial activity and confers in vivo resistance upon transfer into germ free mice. Thus, we demonstrate a defensive role of the gut microbiota against Listeria monocytogenes infection and identify intestinal commensal species that, by enhancing resistance against this pathogen, represent potential probiotics.

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Virulence Testing of Listeria monocytogenes

Journal of AOAC International ◽

10.1093/jaoac/85.2.516 ◽

2002 ◽

Vol 85 (2) ◽

pp. 516-523 ◽

Cited By ~ 15

Author(s):

Richard B Raybourne

Keyword(s):

Listeria Monocytogenes ◽

Virulence Factors ◽

Animal Studies ◽

Virulence Genes ◽

Model Systems ◽

Host Susceptibility ◽

Cell Culture Systems ◽

Small Subpopulation

Abstract A major problem in understanding foodborne listeriosis from both the basic science and regulatory perspectives revolves around the role played by virulence factors of Listeria monocytogenes and how these interact with host susceptibility to result in the observed incidence of disease. From a mechanistic perspective, this problem has been well investigated, and many virulence components of L. monocytogenes have been discovered. Deletion of these genes results in large reductions in virulence functions in vitro and in vivo. The clonal bacteria and genetically identical hosts necessary to solve the riddles associated with virulence mechanisms are not likely to reflect the natural diversity found among wild populations of L. monocytogenes, including those associated with food. These factors contribute to a major dilemma in risk assessment and risk management of foodborne listeriosis: Although low-level L. monocytogenes contamination of certain foods is relatively common, suggesting widespread exposure, illness is overwhelmingly associated with only a relatively small subpopulation (3 of the 13 L. monocytogenes serotypes) and occurs in only a small proportion of susceptible individuals. Virulence testing based on DNA probes for virulence genes is confounded by the widespread distribution of these genes in food isolates. In terms of the distribution of virulence factors among food isolates of L. monocytogenes, only listeriolysin is well characterized, because β-hemolysis is often used to confirm the presence of L. monocytogenes in foods. The presence of other virulence genes such as those involved in host cell invasion and cell-to-cell spread (inIA and actA) among food isolates has not been extensively investigated. How the presence of these components translates into functional virulence as measured in vivo and in vitro is also unknown. Animal studies and cell culture systems show a range of virulence among food isolates of L. monocytogenes. However, clinical isolates included in such studies are not consistently more virulent than food isolates with no known human disease association. Where multiple serotypes or ribotypes are compared, it has been difficult to demonstrate a consistent pattern of increased virulence associated with any subtype(s) in animal or in vitro studies. Development of model systems that adequately reflect the complexity of the host–pathogen relationship remains a challenge.

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The proteolytic activity of Listeria monocytogenes HtrA

BMC Microbiology ◽

10.1186/s12866-019-1633-1 ◽

2019 ◽

Vol 19 (1) ◽

Author(s):

Carmen M. Abfalter ◽

Sabine Bernegger ◽

Miroslaw Jarzab ◽

Gernot Posselt ◽

Karthe Ponnuraj ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Proteolytic Activity ◽

Foodborne Pathogen ◽

Stationary Growth Phase ◽

Bacterial Survival ◽

Highly Active ◽

Molecule Inhibitor ◽

Casein Zymography ◽

Insight Into

Abstract Background High temperature requirement A (HtrA) is a widely expressed chaperone and serine protease in bacteria. HtrA proteases assemble and hydrolyze misfolded proteins to enhance bacterial survival under stress conditions. Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen that induces listeriosis in humans. In previous studies, it was shown that deletion of htrA in the genome of L. monocytogenes increased the susceptibility to cellular stress and attenuated virulence. However, expression and protease activity of listerial HtrA (LmHtrA) were never analyzed in detail. Results In this study, we cloned LmHtrA wildtype (LmHtrAwt) and generated a proteolytic inactive LmHtrASA mutant. Recombinant LmHtrAwt and LmHtrASA were purified and the proteolytic activity was analyzed in casein zymography and in vitro cleavage assays. LmHtrA activity could be efficiently blocked by a small molecule inhibitor targeting bacterial HtrA proteases. The expression of LmHtrA was enhanced in the stationary growth phase of L. monocytogenes and significantly contributed to bacterial survival at high temperatures. Conclusions Our data show that LmHtrA is a highly active caseinolytic protease and provide a deeper insight into the function and mechanism, which could lead to medical and biotechnological applications in the future.

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