Effects of lactic acid stress with lactic acid adaptation on the survival and expression of virulence‐related genes in Escherichia coli O157:H7

2019 ◽  
Vol 39 (6) ◽  
Author(s):  
Lanlin Yu ◽  
Saisai Ji ◽  
Jinlong Yu ◽  
Wenjing Fu ◽  
Lin Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Acid Stress ◽  
Escherichia Coli O157 ◽  
Acid Adaptation

Acid Stress, Starvation, and Cold Stress Affect Poststress Behavior of Escherichia coli O157:H7 and Nonpathogenic Escherichia coli†

2001 ◽  
Vol 64 (7) ◽  
pp. 970-974 ◽  
Author(s):  
B. LEENANON ◽  
M. A. DRAKE
Keyword(s):  
Escherichia Coli ◽  
Heat Resistance ◽  
Cold Stress ◽  
Acid Stress ◽  
Escherichia Coli O157 ◽  
Acid Adaptation ◽  
E Coli ◽  
Freeze Thaw ◽  
Acid Shock ◽  
Rpos Mutant

The effects of acid shock, acid adaptation, starvation, and cold stress of Escherichia coli O157:H7 (ATCC 43895), an rpo S mutant (FRIK 816-3), and nonpathogenic E. coli (ATCC 25922) on poststress heat resistance and freeze–thaw resistance were investigated. Following stress, heat tolerance at 56°C and freeze–thaw resistance at −20 to 21°C were determined. Heat and freeze–thaw resistance of E. coli O157:H7 and nonpathogenic E. coli was enhanced after acid adaptation and starvation. Following cold stress, heat resistance of E. coli O157:H7 and nonpathogenic E. coli was decreased, while freeze–thaw resistance was increased. Heat and freeze–thaw resistance of the rpoS mutant was enhanced only after acid adaptation. Increased or decreased tolerance of acid-adapted, starved, or cold-stressed E. coli O157:H7 cells to heat or freeze–thaw processes should be considered when processing minimally processed or extended shelf-life foods.

Validation of Methods Used To Recover Escherichia coli O157:H7 and Salmonella spp. Subjected to Stress Conditions†

2001 ◽  
Vol 64 (10) ◽  
pp. 1466-1471 ◽  
Author(s):  
M. M. BRASHEARS ◽  
A. AMEZQUITA ◽  
J. STRATTON
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Acid Stress ◽  
Stress Conditions ◽  
Escherichia Coli O157 ◽  
Salmonella Spp ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Resistant Strains ◽  
Stressed Cells

Escherichia coli O157:H7, Salmonella spp., and Salmonella Typhimurium DT104 were stressed with lactic acid and cell-free supernatants from lactic acid bacteria and plated on three different media to determine if injured cells were recovered. A comparison of the susceptibility and recovery of antibiotic-resistant strains of the pathogens and nonresistant strains was also made. Acid stress conditions were created by adjusting the pH of a cocktail mixture (two to four strains) of the pathogen to 3.50 with lactic acid and holding for 18 h. The pathogen cocktail was also stressed with a cell-free supernatant of Lactobacillus lactis (pH 3.90) in a 4:6 ratio. Both nonstressed and stressed cocktail cultures were plated on Trypticase soy agar (TSA) and violet red bile agar (VRBA) for E. coli and xylose lysine tergitol4 (XLT4) for Salmonella. Repair of injured cells was evaluated by pour plating the stressed cells on a 5-ml thin layer of TSA and allowing a 2-h room temperature incubation followed by overlaying with VRBA or XLT4. There were significant reductions in the populations of both pathogens under both stress conditions when plating was done on nonselective media. Injured E. coli O157:H7 was not recovered on recovery or selective media compared with TSA. Numbers of cells of supernatant-stressed Salmonella spp. plated on selective and recovery media were similar to those on TSA. Acid-stressed cells for all Salmonella spp. were not recovered on TSA, selective, or recovery media at levels comparable to recovery on TSA. Antibiotic-resistant strains showed similar recovery patterns on all media evaluated. However, the antibiotic-resistant strains were less sensitive to both stress conditions. The use of antibiotic-resistant strains resulted in a greater recovery of stressed pathogens than the use of recovery media.

Effect of lactic acid stress on biofilm formation of Escherichia coli O26 at different temperatures

2020 ◽  
Author(s):  
Xiaoyu Mi ◽  
Jie Hu ◽  
Su Zhang ◽  
Siqi Wang ◽  
Wangchen Zhao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Biofilm Formation ◽  
Acid Stress ◽  
Different Temperatures

Inactivation of Escherichia coli O157:H7, Salmonella enterica Serotype Enteritidis, and Listeria monocytogenes on Lettuce by Hydrogen Peroxide and Lactic Acid and by Hydrogen Peroxide with Mild Heat

2002 ◽  
Vol 65 (8) ◽  
pp. 1215-1220 ◽  
Author(s):  
CHIA-MIN LIN ◽  
SARAH S. MOON ◽  
MICHAEL P. DOYLE ◽  
KAY H. McWATTERS
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Salmonella Enteritidis ◽  
Sensory Characteristics ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Log Reduction

Iceberg lettuce is a major component in vegetable salad and has been associated with many outbreaks of foodborne illnesses. In this study, several combinations of lactic acid and hydrogen peroxide were tested to obtain effective antibacterial activity without adverse effects on sensory characteristics. A five-strain mixture of Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis, and Listeria monocytogenes was inoculated separately onto fresh-cut lettuce leaves, which were later treated with 1.5% lactic acid plus 1.5% hydrogen peroxide (H2O2) at 40°C for 15 min, 1.5% lactic acid plus 2% H2O2 at 22°C for 5 min, and 2% H2O2 at 50°C for 60 or 90 s. Control lettuce leaves were treated with deionized water under the same conditions. A 4-log reduction was obtained for lettuce treated with the combinations of lactic acid and H2O2 for E. coli O157:H7 and Salmonella Enteritidis, and a 3-log reduction was obtained for L. monocytogenes. However, the sensory characteristics of lettuce were compromised by these treatments. The treatment of lettuce leaves with 2% H2O2 at 50°C was effective not only in reducing pathogenic bacteria but also in maintaining good sensory quality for up to 15 days. A ≤4-log reduction of E. coli O157:H7 and Salmonella Enteritidis was achieved with the 2% H2O2 treatment, whereas a 3-log reduction of L. monocytogenes was obtained. There was no significant difference (P > 0.05) between pathogen population reductions obtained with 2% H2O2 with 60- and 90-s exposure times. Hydrogen peroxide residue was undetectable (the minimum level of sensitivity was 2 ppm) on lettuce surfaces after the treated lettuce was rinsed with cold water and centrifuged with a salad spinner. Hence, the treatment of lettuce with 2% H2O2 at 50°C for 60 s is effective in initially reducing substantial populations of foodborne pathogens and maintaining high product quality.

Survival of Escherichia coli O157:H7 after application of lactic acid bacteria

2018 ◽  
Vol 99 (4) ◽  
pp. 1548-1553 ◽  
Author(s):  
Angela Laury-Shaw ◽  
Sara Elizabeth Gragg ◽  
Alejandro Echeverry ◽  
Mindy M Brashears
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Escherichia Coli O157

scholarly journals Effects of Acid Adaptation, Product pH, and Heating on Survival of Escherichia coli O157:H7 in Pepperoni

2000 ◽  
Vol 66 (4) ◽  
pp. 1726-1729 ◽  
Author(s):  
Denise C. R. Riordan ◽  
Geraldine Duffy ◽  
James J. Sheridan ◽  
Richard C. Whiting ◽  
Ian S. Blair ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Thermal Inactivation ◽  
Escherichia Coli O157 ◽  
Acid Adaptation ◽  
E Coli

ABSTRACT The thermotolerance of E. coli O157:H7 cells (strain 380-94) heated in pepperoni is reported. Information on the pattern of thermal inactivation of E. coli O157:H7 in pepperoni was applied in the development of heating processes designed to reduceE. coli O157:H7 numbers therein by 5 log10units.

Influence of Sodium Chloride on Growth of Lactic Acid Bacteria and Subsequent Destruction of Escherichia coli O157:H7 during Processing of Lebanon Bologna

2001 ◽  
Vol 64 (8) ◽  
pp. 1145-1150 ◽  
Author(s):  
NAVEEN CHIKTHIMMAH ◽  
RAMASWAMY C. ANANTHESWARAN ◽  
ROBERT F. ROBERTS ◽  
EDWARD W. MILLS ◽  
STEPHEN J. KNABEL
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Low Ph ◽  
Escherichia Coli O157 ◽  
Quality Changes ◽  
E Coli ◽  
Fermented Product ◽  
Nacl Concentration ◽  
Different Levels

Due to undesirable quality changes, Lebanon bologna is often processed at temperatures that do not exceed 48.8°C (120°F). Therefore, it is important to study parameters that influence the destruction of Escherichia coli O157:H7 in Lebanon bologna. The objective of the present study was to determine the influence of curing salts (NaCl and NaNO2) on the destruction of E. coli O157:H7 during Lebanon bologna processing. Fermentation to pH 4.7 at 37.7°C reduced populations of E. coli O157:H7 by approximately 0.3 log10, either in the presence or absence of curing salts. Subsequent destruction of E. coli O157:H7 during heating of fermented product to 46.1°C was significantly reduced by the presence of 3.5% NaCl and 156 ppm NaNO2, compared to product without curing salts (P < 0.01). The presence of a higher level of NaCl (5%) in Lebanon bologna inhibited the growth of lactic acid bacteria (LAB), which yielded product with higher pH (~5.0) and significantly reduced the destruction of E. coli O157:H7 even further (P < 0.05). Lower concentrations of NaCl (0, 2.5%) yielded Lebanon bologna with higher LAB counts and lower pHs, compared to product with 5% NaCl. When lactic acid was used to adjust pH in product containing different levels of NaCl, it was determined that low pH was directly influencing destruction of E. coli O157:H7, not NaCl concentration.

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