scholarly journals Complete genome of the barotolerant Listeria monocytogenes RO15 strain and comparison with other strains isolated from food and food processing environments

2020 ◽  
Author(s):  
Ilhan Cem Duru ◽  
Margarita Andreevskaya ◽  
Pia Laine ◽  
Tone Mari Rode ◽  
Anne Ylinen ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Foodborne Pathogens ◽  
Genome Analysis ◽  
Food Processing ◽  
Viable Cell ◽  
High Pressure Processing ◽  
Genome Comparison ◽  
Cell Counts ◽  
Reference Type ◽  
Pressure Tolerance

Abstract Background: High pressure processing (HPP; i.e. 100 - 600 MPa pressure depending on product) is a non-thermal preservation technique adopted by the food industry to decrease significantly foodborne pathogens, including Listeria monocytogenes, from food. However, susceptibility towards pressure differs among diverse strains of L. monocytogenes and it is unclear if this is related to their genomic content. Here, we tested the barotolerance of 10 different L. monocytogenes strains, from food and food processing environments and widely used reference type strains, to pressure treatments with 400 and 600 MPa. Genome sequencing and genome comparison of the tested L. monocytogenes strains were performed to investigate the relation between genomic profile and pressure tolerance.Results: None of the tested strains were tolerant to 600 MPa. A reduction of more than 5 log10 was observed for all strains after 1 minute 600 MPa pressure treatment. L. monocytogenes strain RO15 showed no significant reduction in viable cell counts after 400 MPa for 1 minute and was therefore defined as barotolerant. Genome analysis of so far unsequenced L. monocytogenes strain RO15, 2HF33, MB5, AB199, AB120, C7, and RO4 allowed us to compare the gene content of all strains tested. This revealed that the three most pressure tolerant strains had more than one CRISPR system with self-targeting spacers. Furthermore, several anti-CRISPR genes were detected in these strains. Pan-genome analysis showed that 10 prophage genes were significantly associated with the three most barotolerant strains.Conclusions: L. monocytogenes strain RO15 was the most pressure tolerant among the selected strains. Genome comparison suggests that there might be a relationship between prophages and pressure tolerance in L. monocytogenes.

scholarly journals Complete genome of the barotolerant Listeria monocytogenes RO15 strain and comparison with other strains isolated from food and food processing environments

2020 ◽  
Author(s):  
Ilhan Cem Duru ◽  
Margarita Andreevskaya ◽  
Pia Laine ◽  
Tone Mari Rode ◽  
Anne Ylinen ◽  
...  
Keyword(s):  
High Pressure ◽  
Listeria Monocytogenes ◽  
Genome Sequencing ◽  
Viable Cell ◽  
High Pressure Processing ◽  
Genome Comparison ◽  
Cell Counts ◽  
Genome Wide ◽  
Contaminated Food ◽  
Pressure Resistance

Abstract Background Consumption of Listeria monocytogenes contaminated food can cause infection with a high mortality rate in humans and animals. High pressure processing (HPP) is a non-thermal preservation technique adopted by the food industry to inactivate food pathogens, including L. monocytogenes. Strains of L. monocytogenes show different level of resistance to the high pressure. Some strains resist up to 500 MPa pressure. Here, we tested the pressure resistance of 10 different L. monocytogenes strains, including field isolates and widely used type strains, to 400 and 600 MPa pressure treatments. Genome sequencing, and genome comparison of the tested L. monocytogenes strains were performed to investigate the relation between genomic profile and pressure resistance. Results In this study, we showed that none of the tested strains were resistant to 600 MPa, more than 5 log 10 reduction observed for all strains after 1 minute 600 MPa pressure treatment. However, L. monocytogenes strain RO15 showed no significant reduction in viable cell counts after 400 MPa for 1 minute and it was defined as barotolerant. Genome sequencing of so far unsequenced L. monocytogenes strain RO15, 2HF33, MB5, AB199, AB120, C7, and RO4 allowed us to compare their gene content. Genome comparison of 10 tested strains showed that the three most pressure tolerant strains had more than one CRISPR system with self-targeting spacers. Further, several anti-CRISPR genes were detected in these strains. Pan-genome wide analysis showed that 10 prophage genes were significantly associated with the three most barotolerant strains. Conclusions L. monocytogenes strain RO15 was the most pressure tolerant among the selected strains. Genome comparison suggests that there might be a relationship with prophages, CRISPR systems and pressure resistance in L. monocytogenes .

Assay of Enterocin AS-48 for Inhibition of Foodborne Pathogens in Desserts

2009 ◽  
Vol 72 (8) ◽  
pp. 1654-1659 ◽  
Author(s):  
PILAR MARTINEZ VIEDMA ◽  
HIKMATE ABRIOUEL ◽  
NABIL BEN OMAR ◽  
ROSARIO LUCAS LÓPEZ ◽  
EVA VALDIVIA ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Bacillus Cereus ◽  
Proteolytic Activity ◽  
Foodborne Pathogens ◽  
Viable Cell ◽  
Inoculum Size ◽  
Cell Counts

Enterocin AS-48 was tested against Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes in different kinds of desserts. The highest activity against S. aureus was detected in baker cream. However, in yogurt-type soy-based desserts and in gelatin pudding, AS-48 (175 arbitrary units [AU]/g) reduced viable cell counts of S. aureus by only 1.5 to 1.8 log units at most. The efficacy of AS-48 in puddings greatly depended on inoculum size, and viable S. aureus counts decreased below detection levels within 24 h for inocula lower than 4 to 5.5 log CFU/g. For L. monocytogenes, bacteriocin concentrations of 52.5 to 87.5 AU/g reduced viable counts below detection levels and avoided regrowth of survivors. The lowest activity was detected in yogurt-type desserts. For B. cereus, viable cell counts were reduced below detection levels for bacteriocin concentrations of 52.5 AU/g in instant pudding without soy or by 175 AU/g in the soy pudding. In gelatin pudding, AS-48 (175 AU/g) reduced viable cell counts of B. cereus below detection levels after 8 h at 10°C or after 48 h at 22°C. Bacteriocin addition also inhibited gelatin liquefaction caused by the proteolytic activity of B. cereus.

scholarly journals Genome Sequencing Identifies Two Nearly Unchanged Strains of Persistent Listeria monocytogenes Isolated at Two Different Fish Processing Plants Sampled 6 Years Apart

2013 ◽  
Vol 79 (9) ◽  
pp. 2944-2951 ◽  
Author(s):  
Anne Holch ◽  
Kristen Webb ◽  
Oksana Lukjancenko ◽  
David Ussery ◽  
Benjamin M. Rosenthal ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Food Processing ◽  
Random Amplified Polymorphic Dna ◽  
The United States ◽  
Genome Comparison ◽  
Physiological Factors ◽  
Content Type ◽  
Human Pathogenic Bacterium ◽  
A Genome ◽  
Genome Analyses

ABSTRACTListeria monocytogenesis a food-borne human-pathogenic bacterium that can cause infections with a high mortality rate. It has a remarkable ability to persist in food processing facilities. Here we report the genome sequences for twoL. monocytogenesstrains (N53-1 and La111) that were isolated 6 years apart from two different Danish fish processers. Both strains are of serotype 1/2a and belong to a highly persistent DNA subtype (random amplified polymorphic DNA [RAPD] type 9). We demonstrate usingin silicoanalyses that both strains belong to the multilocus sequence typing (MLST) type ST121 that has been isolated as a persistent subtype in several European countries. The purpose of this study was to use genome analyses to identify genes or proteins that could contribute to persistence. In a genome comparison, the two persistent strains were extremely similar and collectively differed from the reference lineage II strain, EGD-e. Also, they differed markedly from a lineage I strain (F2365). On the proteome level, the two strains were almost identical, with a predicted protein homology of 99.94%, differing at only 2 proteins. No single-nucleotide polymorphism (SNP) differences were seen between the two strains; in contrast, N53-1 and La111 differed from the EGD-e reference strain by 3,942 and 3,471 SNPs, respectively. We included a persistentL. monocytogenesstrain from the United States (F6854) in our comparisons. Compared to nonpersistent strains, all three persistent strains were distinguished by two genome deletions: one, of 2,472 bp, typically contains the gene forinlF, and the other, of 3,017 bp, includes three genes potentially related to bacteriocin production and transport (lmo2774,lmo2775, and the 3′-terminal part oflmo2776). Further studies of highly persistent strains are required to determine if the absence of these genes promotes persistence. While the genome comparison did not point to a clear physiological explanation of the persistent phenotype, the remarkable similarity between the two strains indicates that subtypes with specific traits are selected for in the food processing environment and that particular genetic and physiological factors are responsible for the persistent phenotype.

scholarly journals Response of Listeria monocytogenes to Disinfection Stress at the Single-Cell and Population Levels as Monitored by Intracellular pH Measurements and Viable-Cell Counts

2009 ◽  
Vol 75 (13) ◽  
pp. 4550-4556 ◽  
Author(s):  
Vicky G. Kastbjerg ◽  
Dennis S. Nielsen ◽  
Nils Arneborg ◽  
Lone Gram
Keyword(s):  
Listeria Monocytogenes ◽  
Single Cell ◽  
Intracellular Ph ◽  
Bacterial Population ◽  
Single Cells ◽  
Viable Cell ◽  
Population Subdivision ◽  
Single Cell Level ◽  
Cell Level ◽  
Cell Counts

ABSTRACT Listeria monocytogenes has a remarkable ability to survive and persist in food production environments. The purpose of the present study was to determine if cells in a population of L. monocytogenes differ in sensitivity to disinfection agents as this could be a factor explaining persistence of the bacterium. In situ analyses of Listeria monocytogenes single cells were performed during exposure to different concentrations of the disinfectant Incimaxx DES to study a possible population subdivision. Bacterial survival was quantified with plate counting and disinfection stress at the single-cell level by measuring intracellular pH (pHi) over time by fluorescence ratio imaging microscopy. pHi values were initially 7 to 7.5 and decreased in both attached and planktonic L. monocytogenes cells during exposure to sublethal and lethal concentrations of Incimaxx DES. The response of the bacterial population was homogenous; hence, subpopulations were not detected. However, pregrowth with NaCl protected the planktonic bacterial cells during disinfection with Incimaxx (0.0015%) since pHi was higher (6 to 6.5) for the bacterial population pregrown with NaCl than for cells grown without NaCl (pHi 5 to 5.5) (P < 0.05). The protective effect of NaCl was reflected by viable-cell counts at a higher concentration of Incimaxx (0.0031%), where the salt-grown population survived better than the population grown without NaCl (P < 0.05). NaCl protected attached cells through drying but not during disinfection. This study indicates that a population of L. monocytogenes cells, whether planktonic or attached, is homogenous with respect to sensitivity to an acidic disinfectant studied on the single-cell level. Hence a major subpopulation more tolerant to disinfectants, and hence more persistent, does not appear to be present.

Antibacterial Effect of Water-Soluble Arrowroot (Puerariae radix) Tea Extracts on Foodborne Pathogens in Ground Beef and Mushroom Soup

2004 ◽  
Vol 67 (9) ◽  
pp. 1953-1956 ◽  
Author(s):  
S. KIM ◽  
D. Y. C. FUNG
Keyword(s):  
Foodborne Pathogens ◽  
Salmonella Enteritidis ◽  
Ground Beef ◽  
Viable Cell ◽  
Water Soluble ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Cell Counts ◽  
Tea Extract ◽  
And Staphylococcus Aureus

Antimicrobial activity of water-soluble arrowroot tea extract was evaluated against Escherichia coli O157:H7, Salmonella enterica Serotype Enteritidis, Listeria monocytogenes, and Staphylococcus aureus in ground beef and mushroom soup. The concentrations of arrowroot tea used were 0, 3, and 6% (wt/wt) for ground beef and 0, 1, 5, and 10% (wt/vol) for mushroom soup. Samples without tea extract were considered controls. Each sample was stored for 0, 1, 3, 5, and 7 days at 7°C for ground beef and for 0, 1, 3, and 5 days at 35°C for mushroom soup. On each sampling time, proper dilutions were spread plated on each pathogen-specific agar. Viable cell counts of each pathogen were performed after incubation at 35°C for 24 to 48 h. For ground beef, Salmonella Enteritidis and L. monocytogenes were slightly suppressed by approximately 1.5 log, compared with the control, on day 7 at 3 and 6% arrowroot tea treatment. For mushroom soup, all test pathogens were suppressed by 6.5, 4.7, 3.4, and 4.3 log at 5% and 6.0, 4.7, 5.0, and 4.3 log at 10% against E. coli O157:H7, Salmonella Enteritidis, L. monocytogenes, and S. aureus, respectively, compared with the control on day 5. Mushroom soup with 1% arrowroot tea also showed 2.3- and 2.7-log growth suppression of Salmonella Enteritidis and S. aureus, respectively, compared with the control on day 5. This study showed that the use of arrowroot tea would effectively inhibit the microbial growth of both gram-negative and gram-positive foodborne pathogens in various foods, especially liquid foods.

Antibacterial Effect of Water-Soluble Tea Extracts on Foodborne Pathogens in Laboratory Medium and in a Food Model†

2004 ◽  
Vol 67 (11) ◽  
pp. 2608-2612 ◽  
Author(s):  
S. KIM ◽  
C. RUENGWILYSUP ◽  
D. Y. C. FUNG
Keyword(s):  
Foodborne Pathogens ◽  
Salmonella Enteritidis ◽  
Brain Heart Infusion ◽  
Ground Beef ◽  
Viable Cell ◽  
Water Soluble ◽  
Brain Heart Infusion Broth ◽  
Cell Counts ◽  
Jasmine Tea ◽  
Food Model

The microbial inhibition of foodborne pathogens was determined in brain heart infusion broth with 10% (wt/vol) water-soluble extracts of green, jasmine, black, dungglre, and oolong tea against Escherichia coli O157:H7, Salmonella enterica serovar Enteritidis, Listeria monocytogenes, and Staphylococcus aureus. The mixed culture (approximately 6.0 log CFU/ml), which was composed of the four pathogens, was inoculated into brain heart infusion broth with and without tea extracts. After incubation at 35°C for 0, 1, 3, and 5 days, proper dilution of each sample was spiral plated on each selective agar. Viable cell counts were performed after incubation at 35°C for 24 to 36 h. Green, jasmine, and black tea exhibited an approximately 5.0-log suppression of S. aureus compared with the control from days 1 to 5. Green and jasmine tea also suppressed the growth of L. monocytogenes by approximately 3.0 log CFU/ml on day 5. In contrast, no tea extracts inactivated E. coli O157:H7 and Salmonella Enteritidis. Based on the result in liquid medium, green and jasmine teas of 0.1% (vol/wt) were individually evaluated for their antimicrobial activity against L. monocytogenes and S. aureus in a food model (ground beef) stored at 7°C for 0, 1, 3, 5, and 7 days. Viable cell counts of total bacteria, L. monocytogenes, and S. aureus in ground beef were not significantly different among green and jasmine tea and the control.

Antimicrobial Performance of Alkaline Ionic Fluid (GC-100X) and Its Ability To Remove Escherichia coli O157:H7 from the Surface of Tomatoes

2003 ◽  
Vol 66 (9) ◽  
pp. 1604-1610 ◽  
Author(s):  
N. H. KWON ◽  
S. H. KIM ◽  
J. Y. KIM ◽  
J. Y. LIM ◽  
J. M. KIM ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Hard Water ◽  
Viable Cell ◽  
Organic Load ◽  
Korean Isolate ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Cell Counts ◽  
Chlorine Water

An efficacy test of GC-100X, a noncorrosive alkaline ionic fluid (pH 12) composed of free radicals and supplemented with xylitol, was carried out against six major foodborne pathogens—Staphylococcus aureus FRI 913, Salmonella enterica serovar Enteritidis ATCC 13076, S. enterica serovar Typhimurium DT104 Korean isolate, Vibrio parahaemolyticus ATCC 17803, Escherichia coli O157:H7 ATCC 43894, and Pseudomonas aeruginosa KCTC 1637—at three different temperatures (4, 25, and 36°C) with or without organic load (2% yeast extract). Results revealed a more than 4-log10 (CFU/ml) reduction (1.0 × 104 CFU/ml reduction) against all pathogens reacted at 37°C for 3 h in the absence of organic material. GC-100X solution diluted with an equal volume of distilled or standard hard water (300 ppm CaCO3) showed effective bactericidal activity, particularly against gram-negative bacteria. Washing efficacy of GC-100X solution was compared against E. coli O157:H7 on cherry tomato surfaces with those of a commercially used detergent and chlorine water (100 ppm). Viable cell counts of E. coli O157:H7 that had penetrated to the cores of tomatoes after sanitizing treatment revealed that GC-100X stock and its 5% diluted solutions had similar washing effects to 100-ppm chlorine water and were more effective than the other kitchen detergent. These results indicate that GC-100X has good bactericidal and sanitizing activities and is useful as a new sanitizer for food safety and kitchen hygiene.

Inactivation Kinetics and Virulence Potential of Salmonella Typhimurium and Listeria monocytogenes Treated by Combined High Pressure and Nisin

2010 ◽  
Vol 73 (12) ◽  
pp. 2203-2210 ◽  
Author(s):  
JINGYU GOU ◽  
HYEON-YONG LEE ◽  
JUHEE AHN
Keyword(s):  
High Pressure ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Foodborne Pathogens ◽  
Pressure Change ◽  
Weibull Model ◽  
B Value ◽  
High Pressure Processing ◽  
Inactivation Kinetics ◽  
Molecular Characteristics

The aim of this study was to characterize the physiological and molecular changes of Salmonella Typhimurium and Listeria monocytogenes in deionized water (DIW) and nisin solutions (100 IU/g) during high pressure processing (HPP). Strains of Salmonella Typhimurium and L. monocytogenes in DIW or nisin solutions were subjected to 200, 300, and 400 MPa for 20 min. The Weibull model adequately described the HPP inactivation of Salmonella Typhimurium and L. monocytogenes. Salmonella Typhimurium and L. monocytogenes populations were reduced to less than 1 CFU/ml in DIW and nisin solutions under 400 MPa. The highest b value was 5.75 for Salmonella Typhimurium in nisin solution under 400 MPa. L. monocytogenes was more sensitive to pressure change when suspended in DIW than when suspended in nisin. The pressure sensitivity of both Salmonella Typhimurium and L. monocytogenes was higher in DIW solution (141 to 243 MPa) than in nisin solution (608 to 872 MPa). No recovery of HPP-injured cells in DIW and nisin solutions treated at 400 MPa was observed after 7 days of refrigerated storage. The heterogeneity of HPP-treated cells was revealed in flow cytometry dot plots. The transcripts of stn, invA, prfA, and inlA were relatively down-regulated in HPP-treated nisin solution. The combination of high pressure and nisin could noticeably suppress the expression of virulence-associated genes. These results provide useful information for understanding the physiological and molecular characteristics of foodborne pathogens under high-pressure stress.

scholarly journals Temperature Effect on Listeria Monocytogenes Planktonic Growth and Biofilm-Forming Ability

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Joana Catarina Andrade ◽  
◽  
Rita Bernardo ◽  
António Salvador Barreto ◽  
Telmo Nunes ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Temperature Effect ◽  
Optical Density ◽  
Crystal Violet ◽  
Biofilm Formation ◽  
Viable Cell ◽  
Crystal Violet Staining ◽  
Cell Counts ◽  
Viable Cells ◽  
Density Results

Listeria Monocytogenes is an important foodborne pathogen with the capacity to grow at low temperatures and the ability to form biofilms. These features are particularly significant to food business operators producing readyto-eat foods with a long refrigerated shelf-life not undergoing any listericidal treatment before consumption. Objectives: This work aims to assess the temperature effect on L. monocytogenes growth in planktonic suspension and in mono-species biofilms. Methods and results: Isothermal planktonic growth at 12o C and 37o C was assayed using viable cell counts and optical density measurements that revealed a strong positive correlation, confirming the reliability of combining both methods to estimate L. monocytogenes concentration. Experimental data were then fitted to Baranyi and Roberts primary predictive model and the estimated growth parameters confirmed that μmax at 37o C (0.375 ± 0.072 log Cfu/ ml/h) was higher than at 120 C (0.054 ± 0.001 log Cfu/ml/h), with identical L. monocytogenes final concentrations which emphasizes its ability to grow at refrigerated temperatures. Experimental results from the isothermal growth assay and ComBase Predictor growth model were similar, with slightly higher estimated μmax (37o C: 0.480 log Cfu/ml/h; 12o C: 0.068 log Cfu/ml/h) in the predictor growth model. The studied strains demonstrated biofilm-forming ability at 12o C, 20o C and 300 C after 5 days of growth. No significant differences in biofilm formation at different temperatures were detected considering viable cell counts values, but when using crystal violet staining optical density results significant differences were found, with the highest formation occurring at 30ºC. A positive strong correlation was found between viable cell counts and crystal violet staining optical density results. In fact, both methods complement each other, because while viable cell counts measures viable cells, crystal violet staining optical density considers total biomass (viable and non-viable cells and extracellular matrix components). Nevertheless, in this work all L. monocytogenes strains revealed to be weak biofilm producers. Conclusion: Overall, this studys results contribute with important initial information on L. monocytogenes growth and biofilm formation to further assist predictive growth modeling in food matrices and environments, also enabling subsequent quantitative microbial risk assessment, to improve pathogen’s control.

scholarly journals Antimicrobial Effect of Guava Products against Foodborne Pathogens

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 778A-778
Author(s):  
Guochen Yang* ◽  
Salam A. Ibrahim ◽  
Carl E. Niedziela
Keyword(s):  
Foodborne Pathogens ◽  
Block Design ◽  
Foodborne Pathogen ◽  
Water Extract ◽  
Antimicrobial Effect ◽  
Viable Cell ◽  
Leaf Extracts ◽  
E Coli ◽  
Cell Counts ◽  
Survival And Growth

This study investigated antimicrobial effects of guava products on the survival and growth of Escherichia coli O157:H7 in liquid medium. Seven strains of E. coli O157:H7 (944, 380, E0019, F4546, H1730, Cider, 9727) were tested. These strains were maintained in BHI broth. Guava fruits were sliced into small pieces and blended using a blender. Guava juice and leaves were then extracted using three solvents: water, methanol and hexane. Fruit extracts were dissolved in 10 ml BHI broth tubes to make a fruit solution of 5% (w/v). E. coli O157:H7 was inoculated into fruit solutions at 2 log cfu/mL. After incubation at 37 °C for 24 h, samples were serially diluted 10 folds. The proper diluent was spread-plated on TSA in duplicate. After incubation at 35 °C for 24 h, viable cell counts were obtained. The experiment was replicated three times in a randomized complete-block design. Results demonstrated that guava products (fruit, juice, and leaf extracts) significantly reduced survival and growth of the tested foodborne pathogen strains. Water extract showed the highest antimicrobial activity, followed by methanol and hexane. These results indicate guava extracts are a potential antimicrobial agent to ensure food safety.

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