Changes in Heat Resistance Resulting from pH and Nutritional Shifts of Acid-Adapted and Non–Acid-Adapted Listeria monocytogenes Scott A†

2004 ◽  
Vol 67 (2) ◽  
pp. 316-321 ◽  
Author(s):  
DARRELL O. BAYLES
Keyword(s):  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Frequency Distribution ◽  
Culture Supernatant ◽  
Physiological State ◽  
Distribution Data ◽  
Treatment Conditions ◽  
Lower Heat ◽  
Full Factorial ◽  
Cell Free Culture Supernatant

Stationary-phase Listeria monocytogenes cells that were either pH dependent acid adapted or not acid adapted were heat challenged at 60°C in a two-level full factorial design for three variables. The three variables and the levels consisted of tryptic soy broth (TSB) and sterile cell-free culture supernatant (sterile TSB), the presence and absence of 1% added glucose, and pH 4.8 and pH 7. Non–acid-adapted cells were most heat resistant when challenged in TSB (mean decimal reduction times at 60°C: D60 = 1.16 min). In the absence of added glucose, non–acid-adapted cells had similar D60-values for inactivations at pH 4.8 and pH 7; however, the presence of glucose caused non–acid-adapted cells challenged at pH 4.8 to be more heat sensitive (D60 = 0.65 min) than those inactivated at pH 7 (D60 = 1.03 min), indicating an interaction between glucose and pH. Overall, the significantly decreased heat resistance of the acid-adapted cells was due to the presence of glucose (D60 = 0.78 min without glucose, D60 = 0.59 min with glucose). Acid-adapted cells heat challenged in TSB had similar D60-values for inactivations at pH 4.8 and pH 7; however, acid-adapted cells in sterile TSB challenged at pH 4.8 (D60 = 0.52 min) had significantly lower heat resistance than did cells challenged at pH 7 (D60 = 0.76 min), indicating an interaction between the medium and pH. The L. monocytogenes survivor data were modeled to extract information on the frequency distribution of heat resistance within heat-challenged populations, and the frequency distribution characteristics of mean, mode, and variance were compared among treatment conditions. Significant differences in the frequency distribution data were compared with the D60-values. These data indicated that the presence and level of cross-protection is highly dependent on the physiological state of the cells and nutrient availability at the time of heat challenge. Such conditions should be considered to ensure that stressed pathogens in foods are destroyed or inactivated.

scholarly journals Production of biologically active human interleukin-10 by Bifidobacterium bifidum BGN4

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Nayoun Hong ◽  
Seockmo Ku ◽  
Kyungjin Yuk ◽  
Tony V. Johnston ◽  
Geun Eog Ji ◽  
...  
Keyword(s):  
Culture Supernatant ◽  
Shuttle Vector ◽  
Sodium Dodecyl ◽  
Interleukin 10 ◽  
Biologically Active ◽  
Enzyme Linked Immunosorbent Assay ◽  
Functional Evaluation ◽  
Ht 29 ◽  
Cell Free Culture Supernatant

Abstract Background Bifidobacterium spp. are representative probiotics that play an important role in the health of their hosts. Among various Bifidobacterium spp., B. bifidum BGN4 exhibits relatively high cell adhesion to colonic cells and has been reported to have various in vivo and in vitro bio functionalities (e.g., anti-allergic effect, anti-cancer effect, and modulatory effects on immune cells). Interleukin-10 (IL-10) has emerged as a major suppressor of immune response in macrophages and other antigen presenting cells and plays an essential role in the regulation and resolution of inflammation. In this study, recombinant B. bifidum BGN4 [pBESIL10] was developed to deliver human IL-10 effectively to the intestines. Results The vector pBESIL10 was constructed by cloning the human IL-10 gene under a gap promoter and signal peptide from Bifidobacterium spp. into the E. coli-Bifidobacterium shuttle vector pBES2. The secreted human IL-10 from B. bifidum BGN4 [pBESIL10] was analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), Western Blotting, and enzyme-linked immunosorbent assay (ELISA). More than 1,473 ± 300 ng/mL (n = 4) of human IL-10 was obtained in the cell free culture supernatant of B. bifidum BGN4 [pBESIL10]. This productivity is significantly higher than other previously reported human IL-10 level from food grade bacteria. In vitro functional evaluation of the cell free culture supernatant of B. bifidum BGN4 [pBESIL10] revealed significantly inhibited interleukin-6 (IL-6) production in lipopolysaccharide (LPS)-induced Raw 264.7 cells (n = 6, p < 0.0001) and interleukin-8 (IL-8) production in LPS-induced HT-29 cells (n = 6, p < 0.01) or TNFα-induced HT-29 cells (n = 6, p < 0.001). Conclusion B. bifidum BGN4 [pBESIL10] efficiently produces and secretes significant amounts of biologically active human IL-10. The human IL-10 production level in this study is the highest of all human IL-10 production reported to date. Further research should be pursued to evaluate B. bifidum BGN4 [pBESIL10] producing IL-10 as a treatment for various inflammation-related diseases, including inflammatory bowel disease, rheumatoid arthritis, allergic asthma, and cancer immunotherapy.

Modeling the Effects of Temperature, Sodium Chloride, and Green Tea and Their Interactions on the Thermal Inactivation of Listeria monocytogenes in Turkey†

2014 ◽  
Vol 77 (10) ◽  
pp. 1696-1702 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
JIMENA GARCIA-DÁVILA ◽  
JULIO CESAR LOPEZ-ROMERO ◽  
ETNA AIDA PENA-RAMOS ◽  
JUAN PEDRO CAMOU ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Sodium Chloride ◽  
Protective Effect ◽  
Heat Resistance ◽  
Green Tea ◽  
Thermal Inactivation ◽  
Heating Temperature ◽  
Lethal Effect ◽  
Interactive Effects ◽  
D Values

The interactive effects of heating temperature (55 to 65°C), sodium chloride (NaCl; 0 to 2%), and green tea 60% polyphenol extract (GTPE; 0 to 3%) on the heat resistance of a five-strain mixture of Listeria monocytogenes in ground turkey were determined. Thermal death times were quantified in bags that were submerged in a circulating water bath set at 55, 57, 60, 63, and 65°C. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. D-values were analyzed by second-order response surface regression for temperature, NaCl, and GTPE. The data indicated that all three factors interacted to affect the inactivation of the pathogen. The D-values for turkey with no NaCl or GTPE at 55, 57, 60, 63, and 65°C were 36.3, 20.8, 13.2, 4.1, and 2.9 min, respectively. Although NaCl exhibited a concentration-dependent protective effect against heat lethality on L. monocytogenes in turkey, addition of GTPE rendered the pathogen more sensitive to the lethal effect of heat. GTPE levels up to 1.5% interacted with NaCl and reduced the protective effect of NaCl on heat resistance of the pathogen. Food processors can use the predictive model to design an appropriate heat treatment that would inactivate L. monocytogenes in cooked turkey products without adversely affecting the quality of the product.

Anti-tumor potential of cell free culture supernatant of Lactobacillus rhamnosus strains isolated from human breast milk

2019 ◽  
Vol 123 ◽  
pp. 286-297 ◽  
Author(s):  
Muhammad Shahid Riaz Rajoka ◽  
Haobin Zhao ◽  
Hafiza Mahreen Mehwish ◽  
Na Li ◽  
Yao Lu ◽  
...  
Keyword(s):  
Breast Milk ◽  
Culture Supernatant ◽  
Lactobacillus Rhamnosus ◽  
Human Breast Milk ◽  
Human Breast ◽  
Cell Free Culture Supernatant

Listeria in Seafoods: A Review

1992 ◽  
Vol 55 (12) ◽  
pp. 1009-1015 ◽  
Author(s):  
RONDA M. DILLON ◽  
THAKOR R. PATEL
Keyword(s):  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Drug Administration ◽  
Food And Drug Administration ◽  
Environmental Contaminant ◽  
Fresh Waters ◽  
Smoked Fish ◽  
Seafood Products ◽  
Crab Meat

Listeria is an environmental contaminant which has been isolated from marine and fresh waters, as well as various seafoods. Furthermore, Listeria, including Listeria monocytogenes, has been isolated from processed seafood products such as smoked fish, cooked and frozen seafoods, marinated fish, surimi products, etc. The pathogen, L. monocytogenes, does have a certain degree of heat resistance. It was found to survive in internally infected shrimp after boiled for up to 5 min. However, the commercial pasteurization process for crab meat was found to be sufficient to inactivate Listeria. The current recovery methodology for L. monocytogenes from seafoods is the Food and Drug Administration Listeria protocol.

Antimicrobial Effects of d-3-Phenyllactic Acid on Listeria monocytogenes in TSB-YE Medium, Milk, and Cheese

1998 ◽  
Vol 61 (10) ◽  
pp. 1281-1285 ◽  
Author(s):  
VIRGINIE DIEULEVEUX ◽  
MICHELINE GUÉGUEN
Keyword(s):  
Listeria Monocytogenes ◽  
Growth Phase ◽  
Physiological State ◽  
Geotrichum Candidum ◽  
Bactericidal Effect ◽  
Exponential Growth Phase ◽  
Bacteriostatic Effect ◽  
Experimental Conditions ◽  
Phenyllactic Acid ◽  
Whole Milk

d-3-Phenyllactic acid is a compound with anti-Listeria activity which is produced and secreted by the yeastlike fungus, Geotrichum candidum. This compound has a bactericidal effect independent of the physiological State of Listeria monocytogenes when added at a concentration of 7 mg/ml to tryptic soy broth supplemented with yeast extract (TSB-YE). An initial L. monocytogenes population of 105 CFU/ml was reduced 100-fold (2 log) after 4 days of culture at 25 °C in TSB-YE containing d-3-phenyllactic acid. The Listeria population was reduced 1,000-fold (3 log) when the compound was added during the exponential growth phase, and was reduced to less than 10 CFU/ml when it was added during the stationary phase. d-3-Phenyllactic acid had a bacteriostatic effect in UHT whole milk, reducing the population by 4.5 log, to give fewer cells than in the control after 5 days of culture. The results obtained with L. monocytogenes at concentrations of 105 and 103 CFU/ml in cheese curds were less conclusive. d-3-Phenyllactic acid was 10 times less active than nisin in our experimental conditions (TSB-YE at 25°C).

scholarly journals THE ENHANCEMENT OF MACROPHAGE BACTERIOSTASIS BY PRODUCTS OF ACTIVATED LYMPHOCYTES

1973 ◽  
Vol 138 (4) ◽  
pp. 952-964 ◽  
Author(s):  
Robert E. Fowles ◽  
Ileana M. Fajardo ◽  
Jacques L. Leibowitch ◽  
John R. David
Keyword(s):  
Listeria Monocytogenes ◽  
Guinea Pig ◽  
Concanavalin A ◽  
Bactericidal Activity ◽  
Culture Supernatant ◽  
Cell Adherence ◽  
Activated Lymphocytes ◽  
Glucose Carbon ◽  
Lymphocyte Cultures ◽  
By Products

It was reported previously that the incubation of normal guinea pig macrophages with partially purified products of activated lymphocytes resulted in altered macrophage function including increased cell adherence to culture vessels, spreading, phagocytosis, and glucose carbon-1 oxidation. Studies reported here demonstrate that such macrophages also exhibit enhanced bacteriostasis. Lymphocytes were stimulated with concanavalin A, the culture supernatant was chromatographed over Sephadex G-100 and the fraction of mol wt 25,000–55,000, rich in lymphocyte mediators, was cultured with normal guinea pig macrophages for 1–3 days. Macrophages incubated with fractions from unstimulated lymphocyte cultures served as controls. The resulting macrophage monolayers were infected with Listeria monocytogenes. Macrophages incubated with mediator-rich fractions exhibited 2- to 10-fold enhanced bacteriostasis compared to controls. Further studies indicate that this enhancement was attributable to intrinsic changes in the macrophages and not simply a consequence of the number of macrophages on the monolayers. The studies support the concept that macrophage bacteriostasis can be enhanced by lymphocyte mediators. However, macrophages, which have been preincubated directly with sensitive lymphocytes and antigen exhibit even greater bacteriostasis and sometimes bactericidal capacity, suggesting that either a labile lymphocyte factor or direct lymphocyte macrophage interaction may also be involved in bactericidal activity.

Inactivation of the Crp/Fnr Family of Regulatory Genes in Listeria monocytogenes Strain F2365 Does Not Alter Its Heat Resistance at 60°C†

2006 ◽  
Vol 69 (11) ◽  
pp. 2758-2760 ◽  
Author(s):  
DARRELL O. BAYLES ◽  
GAYLEN A. UHLICH
Keyword(s):  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Thermal Tolerance ◽  
Type Strain ◽  
Transcriptional Control ◽  
Wild Type Strain ◽  
Gene Cassette ◽  
Wild Type ◽  
Mutant Strains ◽  
Virulence Regulator

A surprising facet of the Listeria monocytogenes genome is the presence of 15 genes that code for regulators in the Crp/Fnr family and include the virulence regulator PrfA. The genes under the transcriptional control of these regulators are currently undetermined, with the exception of some genes controlled by the major virulence regulator PrfA. Using 12 strains of L. monocytogenes, each with an inserted gene cassette that interrupts and renders nonfunctional a different L. monocytogenes strain F2365 Crp/Fnr regulator, we heat challenged each strain at 60°C with an immersed-coil heating apparatus, modeled the survivor data to calculate the underlying mean and mode of the heat resistance distribution for each strain, and compared the thermal tolerance of each mutant to the wild-type strain to determine if any of the Crp/Fnr mutants demonstrated altered heat tolerance. All 12 of the Crp/Fnr mutant strains tested had heat resistance characteristics similar to the wild-type strain (P &gt; 0.05), indicating that mutations in these Crp/Fnr genes neither increased nor decreased the sensitivity of L. monocytogenes strain F2365 to mild heat.

Heat‐killed Lactobacillus reuteri and cell‐free culture supernatant have similar effects to viable probiotics during interaction with Porphyromonas gingivalis

2020 ◽  
Vol 55 (2) ◽  
pp. 215-220 ◽  
Author(s):  
Barbara M. C. Geraldo ◽  
Marianna N. Batalha ◽  
Noala V. M. Milhan ◽  
Rodnei D. Rossoni ◽  
Liliana Scorzoni ◽  
...  
Keyword(s):  
Porphyromonas Gingivalis ◽  
Culture Supernatant ◽  
Lactobacillus Reuteri ◽  
Cell Free Culture Supernatant

Thermal Inactivation of Listeria monocytogenes in Chicken Gravy

1992 ◽  
Vol 55 (7) ◽  
pp. 492-496 ◽  
Author(s):  
I-PING D. HUANG ◽  
AHMED E. YOUSEF ◽  
ELMER H. MARTH ◽  
M. EILEEN MATTHEWS
Keyword(s):  
Heat Treatment ◽  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Thermal Inactivation ◽  
Refrigerated Storage ◽  
Department Of Agriculture ◽  
Large Numbers ◽  
Z Value ◽  
D Values ◽  
The U.S

Heat resistance of Listeria monocytogenes strains V7 and Scott A in chicken gravy and changes in heat resistance during refrigerated storage were studied. After chicken gravy was made, it was cooled to 40°C, inoculated with 105 CFU L. monocytogenes per ml of gravy, and then stored at 7°C for 10 d. Gravy was heated at 50, 55, 60, and 65°C immediately after inoculation and after 1, 3, 5, and 10 d of refrigerated storage. The D values for strains Scott A and V7 in gravy heated at 50°C at day 0 were 119 and 195 min and at day 10 they were 115 and 119 min, respectively, whereas at 65°C comparable values at day 0 were 0.48 and 0.19 min and at day 10 they were 0.014 and 0.007 min. Heat resistance (expressed as D values) was greater at day 0 than at the end of refrigerated storage. The z values ranged from 3.41 to 6.10°C and were highest at the early stages of chill storage and then decreased at the later stages. Strain V7 was more heat resistant than Scott A at 50°C. Strain Scott A always had a higher z value than did strain V7 at the same storage interval. A heat treatment greater than the 4-D process recommended by the U.S. Department of Agriculture was required to inactivate the large numbers of L. monocytogenes that developed in chicken gravy during refrigerated storage.

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