Listeriolysin O Secretion by Listeria monocytogenes in Broth Containing Salts of Organic Acids

Antilisterial effects of salts of organic acids have been documented, but there is little information on listeriolysin O (LLO) secretion in the presence of these salts during aerobic and anaerobic incubation. LLO secretion and populations of Listeria monocytogenes were studied in broth containing potassium sorbate (0.05 to 4%), sodium lactate, citrate, acetate, or propionate (0.1 to 8%) after aerobic or anaerobic incubation for 24 h at 35 and 20°C. The order of the antilisterial effects of the salts was propionate > sorbate > acetate > lactate > citrate. Cell proliferation was suppressed during incubation under anaerobic conditions but LLO secretion was enhanced. Citrate, acetate, and lactate enhanced LLO secretion during incubation at 35°C, whereas sorbate suppressed it. Overall, effects of the acids at 20°C were similar to those observed at 35°C, but only acetate and citrate enhanced LLO secretion. The observation that salts of specific organic acids enhance LLO secretion may suggest increased virulence of L. monocytogenes. Combinations of sorbate, an LLO blocking agent, with propionate or lactate, which inhibit proliferation of L. monocytogenes, may prolong the shelf life and increase the safety of foods.

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Transcriptomic Analysis of Listeria monocytogenes in Response to Bile Under Aerobic and Anaerobic Conditions

Frontiers in Microbiology ◽

10.3389/fmicb.2021.754748 ◽

2021 ◽

Vol 12 ◽

Author(s):

Damayanti Chakravarty ◽

Gyan Sahukhal ◽

Mark Arick ◽

Morgan L. Davis ◽

Janet R. Donaldson

Keyword(s):

Listeria Monocytogenes ◽

Stress Responses ◽

Listeriolysin O ◽

Gi Tract ◽

Anaerobic Conditions ◽

Transcript Levels ◽

Comprehensive Information ◽

Associated Proteins ◽

Aerobic And Anaerobic ◽

Aerobic And Anaerobic Conditions

Listeria monocytogenes is a gram-positive facultative anaerobic bacterium that causes the foodborne illness listeriosis. The pathogenesis of this bacterium depends on its survival in anaerobic, acidic, and bile conditions encountered throughout the gastrointestinal (GI) tract. This transcriptomics study was conducted to analyze the differences in transcript levels produced under conditions mimicking the GI tract. Changes in transcript levels were analyzed using RNA isolated from L. monocytogenes strain F2365 at both aerobic and anaerobic conditions, upon exposure to 0 and 1% bile at acidic and neutral pH. Transcripts corresponding to genes responsible for pathogenesis, cell wall associated proteins, DNA repair, transcription factors, and stress responses had variations in levels under the conditions tested. Upon exposure to anaerobiosis in acidic conditions, there were variations in the transcript levels for the virulence factors internalins, listeriolysin O, etc., as well as many histidine sensory kinases. These data indicate that the response to anaerobiosis differentially influences the transcription of several genes related to the survival of L. monocytogenes under acidic and bile conditions. Though further research is needed to decipher the role of oxygen in pathogenesis of L. monocytogenes, these data provide comprehensive information on how this pathogen responds to the GI tract.

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Organic Acids and Their Salts as Dipping Solutions To Control Listeria monocytogenes Inoculated following Processing of Sliced Pork Bologna Stored at 4°C in Vacuum Packages

Journal of Food Protection ◽

10.4315/0362-028x-64.11.1722 ◽

2001 ◽

Vol 64 (11) ◽

pp. 1722-1729 ◽

Cited By ~ 119

Author(s):

JOHN SAMELIS ◽

JOHN N. SOFOS ◽

MINDY L. KAIN ◽

JOHN A. SCANGA ◽

KEITH E. BELK ◽

...

Keyword(s):

Acetic Acid ◽

Listeria Monocytogenes ◽

Organic Acids ◽

Safety Issue ◽

Sodium Lactate ◽

Commercial Application ◽

Potassium Sorbate ◽

Cured Meats ◽

Potassium Benzoate ◽

Sodium Diacetate

Postprocessing contamination of cured meats with Listeria monocytogenes has become a major concern for the meat processing industry and an important food safety issue. This study evaluated aqueous dipping solutions of organic acids (2.5 or 5% lactic or acetic acid) or salts (2.5 or 5% sodium acetate or sodium diacetate, 5 or 10% sodium lactate, 5% potassium sorbate or potassium benzoate) to control L. monocytogenes on sliced, vacuum-packaged bologna stored at 4°C for up to 120 days. Organic acids and salts were applied by immersing (1 min) in each solution inoculated (102 to 103 CFU/cm2) slices of bologna before vacuum packaging. Growth of L. monocytogenes (PALCAM agar) on inoculated bologna slices without treatment exceeded 7 log CFU/cm2 (P < 0.05) at 20 days of storage. No significant (P > 0.05) increase in L. monocytogenes populations occurred on bologna slices treated with 2.5 or 5% acetic acid, 5% sodium diacetate, or 5% potassium benzoate from day 0 to 120. Products treated with 5% potassium sorbate and 5% lactic acid were stored for 50 and 90 days, respectively, before a significant (P < 0.05) increase in L. monocytogenes occurred. All other treatments permitted growth of the pathogen at earlier days of storage, with sodium lactate (5 or 10%) permitting growth within 20 to 35 days. Extent of bacterial growth on trypticase soy agar plus 0.6% yeast extract (TSAYE) was similar to that on PALCAM, indicating that the major part of total bacteria grown on TSAYE agar plates incubated at 30°C was L. monocytogenes. Further studies are needed to evaluate organic acids and salts as dipping solutions at abusive temperatures of retail storage, to optimize their concentrations in terms of product sensory quality, and to evaluate their effects against various other types of microorganisms and on product shelf life. In addition, technologies for the commercial application of postprocessing antimicrobial solutions in meat plants need to be developed.

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Organic Acids and Anaerobic Microorganisms in the Contents of the Cholesteatoma SAC

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348948309200122 ◽

1983 ◽

Vol 92 (1) ◽

pp. 91-96 ◽

Cited By ~ 29

Author(s):

Yukiko Iino ◽

Tomonori Takasaka ◽

Etsuro Hoshino ◽

Yutaka Kaneko ◽

Sachiko Tomioka ◽

...

Keyword(s):

Fatty Acids ◽

Organic Acids ◽

Volatile Fatty Acids ◽

Chromatographic Technique ◽

Anaerobic Conditions ◽

Clostridium Species ◽

Anaerobic Microorganisms ◽

Aerobic And Anaerobic ◽

Aerobic And Anaerobic Conditions

Organic acids in the contents of the cholesteatoma sac from 28 cases were studied by gas chromatographic technique. Five volatile fatty acids (acetate, propionate, isobutyrate, butyrate and isovalerate) and lactate were detected in large amounts, which may lower the pH of the cholesteatoma content. These acids were considered to be derived from products of anaerobic microorganisms. Therefore, the contents from 12 cases were cultured anaerobically in a glove box. Obligate microorganisms were identified in 92% of the cases and Peptococcus, Bacteroides, and Clostridium species were frequently isolated. In vitro, such obligate anaerobes produced various organic acids from the cholesteatoma content. Facultatives such as Staphylococcus aureus and Proteus mirabilis produced acetate in the content under aerobic and anaerobic conditions, whereas no organic acid was produced by Pseudomonas aeruginosa. Organic acids in the cholesteatoma content could be fermentative products made by the microorganisms, anaerobes and facultatives, which use the content as a substrate for acid production.

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Growth of cell wall-defective variants of Escherichia coli: comparison of aerobic and anaerobic induction frequencies

Journal of Clinical Microbiology ◽

10.1128/jcm.6.2.166-171.1977 ◽

1977 ◽

Vol 6 (2) ◽

pp. 166-171

Author(s):

T W Huber ◽

A W Brinkley

Keyword(s):

Escherichia Coli ◽

Cell Wall ◽

High Frequency ◽

Anaerobic Incubation ◽

Anaerobic Conditions ◽

Group Iii ◽

E Coli ◽

Induction Frequency ◽

Group I ◽

Aerobic And Anaerobic

A method for quantitating the conversion of Escherichia coli to colony-forming, cell wall-defective (CWD) bacteria has been developed. The induction frequency, i.e., the percentage of the population recovered as CWD colonies was determined for 20 randomly selected clinical isolates of E. coli under aerobic and anaerobic incubation conditions. Penicillin (1,000 U/ML) was the inducing agent. The 20 strains segregated into three groups. Group I organisms produced CWD colonies with high frequency both aerobically and anaerobically. Grout II organisms showed a much higher induction frequency anaerobically than aerobically. Group III organisms were poor inducers. Thirty percent of the strains were group I, 50% were group II, and 20% were group III organisms. These data indicate that anaerobic conditions enhance the induction and growth of CWD E. coli in the research laboratory and suggest that anaerobic incubation may be important in recovery of medically significant CWD bacteria.

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Validation of Food-Grade Salts of Organic Acids as Ingredients To Control Listeria monocytogenes on Pork Scrapple during Extended Refrigerated Storage†‡

Journal of Food Protection ◽

10.4315/0362-028x.jfp-10-425 ◽

2011 ◽

Vol 74 (3) ◽

pp. 394-402 ◽

Cited By ~ 4

Author(s):

A. C. S. PORTO-FETT ◽

S. G. CAMPANO ◽

J. E. CALL ◽

B. A. SHOYER ◽

L. YODER ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Organic Acids ◽

Phase I ◽

Phase Ii ◽

Storage Period ◽

Phase Iii ◽

Refrigerated Storage ◽

Food Grade ◽

Salts Of Organic Acids ◽

Subsequent Addition

This study was conducted to investigate control of Listeria monocytogenes on pork scrapple during storage at 4°C. In phase I, scrapple was formulated, with or without citrate-diacetate (0.64%), by a commercial processor to contain various solutions or blends of the following antimicrobials: (i) lactate-diacetate (3.0 or 4.0%), (ii) lactate-diacetate-propionate (2.0 or 2.5%), and (iii) levulinate (2.0 or 2.5%). Regardless of whether citrate-diacetate was included in the formulation, without the subsequent addition of the targeted antimicrobials pathogen levels increased ca. 6.4 log CFU/g within the 50-day storage period. In the absence of citrate-diacetate but when the targeted antimicrobials were included in the formulation, pathogen numbers increased by ca. 1.3 to 5.2 log CFU/g, whereas when citrate-diacetate was included with these antimicrobials, pathogen numbers increased only by ca. 0.7 to 2.3 log CFU/g. In phase II, in the absence of citrate-diacetate, when the pH of the lactate-diacetate-propionate blend (2.5%) was adjusted to pH 5.0 or 5.5 pathogen numbers remained unchanged (≤0.5 log CFU/g increase) over 50 days, whereas when citrate-diacetate was included with the lactate-diacetate-propionate blend adjusted to pH 5.0 or 5.5, pathogen numbers decreased by 0.3 to 0.8 log CFU/g. In phase III, when lower concentrations of the lactate-diacetate-propionate blend (1.5 or 1.94%) were adjusted to pH 5.5, pathogen numbers increased by ca. 6.0 and 4.7 log CFU/g, respectively, whereas when the mixture was adjusted to pH 5.0, pathogen numbers increased by ≤0.62 log CFU/g. Thus, scrapple formulated with lactate-diacetate-propionate (1.5 and 1.94% at pH 5.0) is an unfavorable environment for outgrowth of L. monocytogenes.

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Protein Variations in Listeria monocytogenes Exposed to Sodium Lactate, Sodium Diacetate, and Their Combination

Journal of Food Protection ◽

10.4315/0362-028x-70.1.58 ◽

2007 ◽

Vol 70 (1) ◽

pp. 58-64 ◽

Cited By ~ 8

Author(s):

EVELYNE MBANDI ◽

BRETT S. PHINNEY ◽

DOUGLAS WHITTEN ◽

LEORA A. SHELEF

Keyword(s):

Listeria Monocytogenes ◽

Meat Products ◽

Defined Medium ◽

Sodium Lactate ◽

Salt Treatment ◽

Adverse Conditions ◽

Novel Proteins ◽

Proteomic Approach ◽

Salts Of Organic Acids ◽

Sodium Diacetate

Most studies of the effect of adverse conditions on survival of Listeria monocytogenes have focused on stress caused by acid or sodium chloride. However, no information is available on resistance of this pathogen to stress caused by salts of organic acids. Sodium lactate and sodium diacetate are generally recognized as safe substances and are approved as ingredients for use in foods. We evaluated antilisterial properties of each of these salts and the enhanced inhibition effected by their combination in ready-to-eat meat products at pH 6.3. Changes in proteins found in this pathogen were studied in the presence of the salts in a chemically defined medium at the same pH using a proteomic approach. The total numbers of protein spots obtained from two-dimensional electrophoresis were 198, 150, and 131 for sodium diacetate, sodium lactate, and the control, respectively. Sodium diacetate treatment produced the highest number of unmatched proteins (124 versus 53 in lactate), the greatest increase in expression (20 versus 5 in lactate), and the highest number of novel proteins (90 versus 45 in lactate). The number of repressed proteins was highest in the combination treatment (41 versus ∼30 in the single salt treatment). Six proteins that increased or decreased by ≥10-fold were further investigated; oxidoreductase and lipoprotein were upregulated, and DNA-binding protein, alpha amylase, and two SecA proteins were downregulated or completely suppressed by the salt treatment. Identification of all protein spots is essential for comparison with proteins induced or suppressed under other stress conditions.

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The Use of Bacteriocin-Producing Pediococcus acidilactici to Control Postprocessing Listeria monocytogenes Contamination of Frankfurters1

Journal of Food Protection ◽

10.4315/0362-028x-54.9.681 ◽

1991 ◽

Vol 54 (9) ◽

pp. 681-686 ◽

Cited By ~ 71

Author(s):

ELAINE D. BERRY ◽

ROBERT W. HUTKINS ◽

ROGER W. MANDIGO

Keyword(s):

Listeria Monocytogenes ◽

No Reduction ◽

Initial Level ◽

Lag Time ◽

Storage Conditions ◽

Pediococcus Acidilactici ◽

Anaerobic Conditions ◽

Aerobic Conditions ◽

Low Levels ◽

Aerobic And Anaerobic

The ability of a bacteriocin-producing Pediococcus acidilactici to control postprocessing Listeria monocytogenes contamination of frankfurters was examined. Bacteriocin-producing P. acidilactici JD1–23 or its plasmid-cured derivative JD-M and a five-strain composite of L. monocytogenes were inoculated onto fully processed frankfurters. Under normal storage conditions at 4°C under vacuum, L. monocytogenes without added pediococci grew from an initial level of 104 CFU/g to a final level of 106 CFU/g over 60 d, with a lag time of 20–30 d. Under the same conditions, high levels (107 CFU/g) of either pediococcal strain inhibited growth of L. monocytogenes up to 60 d, although no reduction of cells occurred. With low levels of pediococci (103–104 CFU/g), Listeria grew, although the lag time was increased, and a bacteriocin effect was observed on frankfurters inoculated with JD1–23. In additional experiments done at 4°C and 15°C under aerobic and anaerobic conditions, levels of 107–108 CFU/g of either pediococci were observed to control Listeria growth on frankfurters at 15°C under anaerobic conditions for up to 15 d. At 4°C under aerobic conditions, L. monocytogenes grew on frankfurters inoculated with JD-M, while JD1–23 inhibited growth of the organism up to 30 d. At 15°C under aerobic conditions, L. monocytogenes grew in the presence of either pediococci, although a bacteriocin effect was indicated. Package atmosphere was observed to affect L. monocytogenes growth on this product.

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