Study of the inactivation of Escherichia coli and pectin methylesterase in mango nectar under selected high hydrostatic pressure treatments

2011 ◽  
Vol 17 (6) ◽  
pp. 541-547 ◽  
Author(s):  
D. Bermúdez-Aguirre ◽  
J. Ángel Guerrero-Beltrán ◽  
G.V. Barbosa-Cánovas ◽  
J. Welti-Chanes
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Pectin Methylesterase ◽  
E Coli ◽  
Viable Cells ◽  
Plate Counts ◽  
The Media ◽  
Inactivation Effect

High hydrostatic pressure (HHP) was applied to fresh mango nectar (FMN) and sterilized mango nectar (SMN) to inactivate Escherichia coli and pectin methylesterase (PME). Pressure was applied at 275, 345 and 414 MPa. The come-up time (CUT) as well as 1, 2 and 4 min of treatment times were applied at the selected pressure to evaluate the inactivation effect on E. coli and PME. Total plate counts (TPC) were also evaluated in FMN. Results showed that mesophiles are inactivated in FMN to an important degree (up to 4 log) only with the CUT; the highest inactivation for mesophiles (7 log) was reported at 414 MPa after 4 min. Meanwhile, for E. coli 345 and 414 MPa after 2 and 1 min, respectively, were able to inactivate all viable cells in FMN. However, in SMN after 4 min at 275 MPa all cells of E. coli were also inactivated, showing the protective effect of the media between FMN and SMN. The PME showed its resistance to be inactivated with high pressure, showing the highest decrease in enzymatic activity (45%) after 4 min at 345 MPa but with an important activation at the highest pressure (414 MPa).

scholarly journals Heat Shock Protein-Mediated Resistance to High Hydrostatic Pressure in Escherichia coli

2004 ◽  
Vol 70 (5) ◽  
pp. 2660-2666 ◽  
Author(s):  
Abram Aertsen ◽  
Kristof Vanoirbeek ◽  
Philipp De Spiegeleer ◽  
Jan Sermon ◽  
Kristel Hauben ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Hydrostatic Pressure ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
High Hydrostatic Pressure ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
E Coli ◽  
Shock Proteins

ABSTRACT A random library of Escherichia coli MG1655 genomic fragments fused to a promoterless green fluorescent protein (GFP) gene was constructed and screened by differential fluorescence induction for promoters that are induced after exposure to a sublethal high hydrostatic pressure stress. This screening yielded three promoters of genes belonging to the heat shock regulon (dnaK, lon, clpPX), suggesting a role for heat shock proteins in protection against, and/or repair of, damage caused by high pressure. Several further observations provide additional support for this hypothesis: (i) the expression of rpoH, encoding the heat shock-specific sigma factor σ32, was also induced by high pressure; (ii) heat shock rendered E. coli significantly more resistant to subsequent high-pressure inactivation, and this heat shock-induced pressure resistance followed the same time course as the induction of heat shock genes; (iii) basal expression levels of GFP from heat shock promoters, and expression of several heat shock proteins as determined by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins extracted from pulse-labeled cells, was increased in three previously isolated pressure-resistant mutants of E. coli compared to wild-type levels.

scholarly journals Inactivation of Escherichia coli andListeria innocua in Milk by Combined Treatment with High Hydrostatic Pressure and the Lactoperoxidase System

2000 ◽  
Vol 66 (10) ◽  
pp. 4173-4179 ◽  
Author(s):  
Cristina García-Graells ◽  
Caroline Valckx ◽  
Chris W. Michiels
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Combined Treatment ◽  
Food Preservation ◽  
Pressure Treatment ◽  
E Coli ◽  
Preservation Method ◽  
Lactoperoxidase System

ABSTRACT We have studied inactivation of four strains each ofEscherichia coli and Listeria innocua in milk by the combined use of high hydrostatic pressure and the lactoperoxidase-thiocyanate-hydrogen peroxide system as a potential mild food preservation method. The lactoperoxidase system alone exerted a bacteriostatic effect on both species for at least 24 h at room temperature, but none of the strains was inactivated. Upon high-pressure treatment in the presence of the lactoperoxidase system, different results were obtained for E. coli and L. innocua. For none of the E. coli strains did the lactoperoxidase system increase the inactivation compared to a treatment with high pressure alone. However, a strong synergistic interaction of both treatments was observed for L. innocua. Inactivation exceeding 7 decades was achieved for all strains with a mild treatment (400 MPa, 15 min, 20°C), which in the absence of the lactoperoxidase system caused only 2 to 5 decades of inactivation depending on the strain. Milk as a substrate was found to have a considerable effect protecting E. coli and L. innocua against pressure inactivation and reducing the effectiveness of the lactoperoxidase system under pressure on L. innocua. Time course experiments showed that L. innocua counts continued to decrease in the first hours after pressure treatment in the presence of the lactoperoxidase system.E. coli counts remained constant for at least 24 h, except after treatment at the highest pressure level (600 MPa, 15 min, 20°C), in which case, in the presence of the lactoperoxidase system, a transient decrease was observed, indicating sublethal injury rather than true inactivation.

Combined Effect of High Hydrostatic Pressure and Nisin on Loss of Viability, Membrane Damage and Release of Intracellular Contents of Bacillus subtilis and Escherichia coli

2010 ◽  
Vol 6 (5) ◽  
Author(s):  
Wei-Min Qi ◽  
Ping Qian ◽  
Jian-Yong Yu ◽  
Chi-Yu Zhang ◽  
Xiao Chen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Hydrostatic Pressure ◽  
Synergistic Effect ◽  
High Hydrostatic Pressure ◽  
Cell Envelope ◽  
Membrane Damage ◽  
Combined Effect ◽  
Gram Negative Bacteria ◽  
E Coli

Bacillus subtilis and Escherichia coli were chosen to investigate the combined effect of high hydrostatic pressure (HHP) and Nisin on loss of viability, membrane damage and release of intracellular contents of microorganisms. The results showed that the combination of 200 IU/mL Nisin and HHP exhibited a synergistic effect over 2 log on the inactivation of B. subtilis at pressure 300 MPa. The similar synergistic effect was observed on the membrane damage and release of intracellular contents of B. subtilis. The Nisin alone had no effect against E. coli, which belongs to gram negative bacteria. However, at pressure 300 MPa, Nisin caused the membrane damage from 55% to 80%. The synergistic effect of Nisin and HHP on loss of viability, membrane damage and release of intracellular contents of E. coli were also illustrated when the HHP pressure exceeded 300 MPa as the consequence of the serious changes produced by HHP at higher pressure in the cell envelope. It allows the entry of Nisin molecules to cell membrane.

Fate of Escherichia coli Strains Inoculated in Model Cheese Elaborated with or without Starter and Treated by High Hydrostatic Pressure

2006 ◽  
Vol 69 (12) ◽  
pp. 2856-2864 ◽  
Author(s):  
SÍLVIA DE LAMO-CASTELLVÍ ◽  
MARTA CAPELLAS ◽  
ARTUR X. ROIG-SAGUÉS ◽  
TOMÁS LÓPEZ-PEDEMONTE ◽  
M. MANUELA HERNÁNDEZ-HERRERO ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Culture Medium ◽  
Storage Period ◽  
E Coli ◽  
Ph Values ◽  
Cell Counts ◽  
Agar Layer ◽  
Selective Culture Medium

The aim of this research was to study high hydrostatic pressure inactivation of two strains of Escherichia coli (E. coli O59:H21 [CECT 405] and E. coli O157:H7 [CECT 5947]) inoculated in washed-curd model cheese elaborated with and without starter and the ability of these strains for survival, recovery, and growth. Samples were treated at 300, 400, and 500 MPa for 10 min at 20°C and analyzed after the treatment and after 1, 7, and 15 days of storage at 8°C to study the behavior of Escherichia populations. Cheeses elaborated with starter showed the maximum lethality at 400 and 500 MPa, and no significant differences in the baroresistant behavior of either strains were detected, except for E. coli O157:H7 at 400 MPa in cell counts obtained with thin agar layer method medium, where the decrease value was significantly lower. In cheese elaborated without starter, the highest decrease value was observed at 500 MPa, except for E. coli O59:H21 in cell counts obtained with selective culture medium, where the highest decrease value was also found at 400 MPa. The ability to repair and grow was not observed in model cheese elaborated with starter, as cell counts of treated samples decreased after 15 days of storage at 8°C. By contrast, in cheese elaborated without starter, all pressurized samples showed the trend to repair and grow during the storage period in both strains. These results suggest that the presence of starter and low pH values are the main factors that control the ability of Escherichia strains inoculated in this type of cheese and treated by high hydrostatic pressure to recover and grow.

scholarly journals Variation in Resistance to High Hydrostatic Pressure andrpoS Heterogeneity in Natural Isolates ofEscherichia coli O157:H7

2001 ◽  
Vol 67 (10) ◽  
pp. 4901-4907 ◽  
Author(s):  
Marianne Robey ◽  
Amparo Benito ◽  
Roger H. Hutson ◽  
Cristina Pascual ◽  
Simon F. Park ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
Stationary Phase ◽  
Sigma Factor ◽  
High Hydrostatic Pressure ◽  
E Coli ◽  
Commensal Strain ◽  
Natural Isolates ◽  
Pressure Resistance ◽  
Sigma Factor Rpos

ABSTRACT Several natural isolates of Escherichia coliO157:H7 have previously been shown to exhibit stationary-phase-dependent variation in their resistance to inactivation by high hydrostatic pressure. In this report we demonstrate that loss of the stationary-phase-inducible sigma factor RpoS resulted in decreased resistance to pressure inE. coli O157:H7 and in a commensal strain. Furthermore, variation in the RpoS activity of the natural isolates of O157:H7 correlated with the pressure resistance of those strains. Heterogeneity was noted in the rpoS alleles of the natural isolates that may explain the differences in RpoS activity. These results are consistent with a role for rpoS in mediating resistance to high hydrostatic pressure in E. coliO157:H7.

Note: Ultra High Hydrostatic Pressure Inactivation of Escherichia Coli in Milk, and Orange and Peach Juices

2003 ◽  
Vol 9 (6) ◽  
pp. 403-407 ◽  
Author(s):  
C. Dogan ◽  
O. Erkmen
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
Cell Growth ◽  
Orange Juice ◽  
High Hydrostatic Pressure ◽  
Raw Milk ◽  
Aerobic Bacteria ◽  
Bacterial Cells ◽  
E Coli ◽  
Peach Juice

Inactivation of Escherichia coli by high hydrostatic pressure (UHHP) was determined in broth, milk and orange and peach juices inoculated with the bacteria. HHP ranged from 200 to 700 MPa at 25 C and different treatment times. No cell growth occurred in broth after 60, 25, 15, 10 and 7 min at 300, 400, 500, 600 and 700 MPa, respectively. Reduction of aerobic bacteria in milk and peach juice were 3.08 and 6.07 log units after 15 min at 400 MPa, respectively, while all bacterial cells were inactivated in orange juice. Sterilisation of raw milk contaminated with E. coli occurred at 600 MPa for 30 min, while peach and orange juices needed 12 and 10 min, respectively. The injury of cells in broth at 300 MPa ranged from 8.8 to 100% depending on magnitude of pressure and treated time. In general, inactivation of aerobic bacteria and E. coli was enhanced significantly (P<0.01) by increasing the pressure.

scholarly journals Frozen strawberry quality enhancement using high hydrostatic pressure and vacuum infusion with pectin methylesterase and calcium chloride solution

2021 ◽  
Vol 21` (01) ◽  
pp. 17290-17312
Author(s):  
Silvenus O Konyole ◽  
◽  
SO Oiye ◽  
GP Okiror ◽  
◽  
...  
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Frozen Storage ◽  
Pectin Methylesterase ◽  
High Pressure Freezing ◽  
Freezing And Thawing ◽  
Significant Difference ◽  
Relative Hardness ◽  
Conventional Freezing

Fresh strawberry(Fragaria x ananassa) is a delicious fruit that is an excellent source of micronutrients and an array of beneficial phytochemicals. Emerging technologies like high pressure freezing and thawing have gained interest recently due to their ability to preserve the structure of the food during storage, albeit the possible shortcomings of degradation of texture and sensory quality. In this study, the effects of high hydrostatic pressure freezing and thawing on the physical quality attributes (texture, drip loss and Degree of Methylation(DM)) of strawberry were investigated. Strawberry samples were infused in a vacuum using pectin methyl esterase(PME) and CaCl2solutionat170 hPa pressure for 5 min at room temperature to improve textural integrity; infused with distilled water; and another group of samples further incubated at 40°C for 20 min. Fresh samples and non-pre treated samples were also studied. All the samples were subjected to high pressure freezing and thawing processes at 200 MPa and the effect of the processing conditions on texture were evaluated. The high pressure processed samples were compared with conventionally frozen and thawed samples.Pectin methyl esterase,CaCl2infusion and incubation gave a relative hardness of 1.5 pre treatment compared to water only infused at 0.5.TheCaCl2and PME-infused samples had a higher relative hardness after one day of storage at -18°C compared to non-pretreated and water-infused samples at 0.3 compared to 0.1,respectively. Pretreated, water-infused, and PME withCaCl2-infused samples showed no significant difference in hardness when measured immediately after conventional thawing and high pressure induced thawing HPIT but are the former are a third less hard compared to the latter upon storage after 3 hours and three months. Galacturonic acid per mg of Alcohol insoluble residues AIR sample for the fresh strawberrywas0.002±2.699E-05 and 0.002±1.070E-05molesfor the one-day vs.three months storage,respectively,for samples conventionally frozen and thawed in duplicate experiments.Therefore,a combination of high-pressure shift freezing (HPSF) with PME and CaCl2infusion improved the texture of the strawberry compared to those that were not pretreated,and gained weight by 15%. The PME and CaCl2-infused strawberry showed less degradation than the non-pretreated and water-infused during both long-and short-time frozen storage. Conventional freezing processes caused more degradation compared to HPSF. Degradation of 3 months conventional freezing was comparable to 1-day storage. For frozen storage, enzyme pretreatment combined with high pressure freezing can be used to enhance the quality of strawberry.

Decontamination of Seeds for Seed Sprout Production by High Hydrostatic Pressure

2003 ◽  
Vol 66 (6) ◽  
pp. 918-923 ◽  
Author(s):  
ELKE Y. WUYTACK ◽  
ANN M. J. DIELS ◽  
KATELIJNE MEERSSEMAN ◽  
CHRIS W. MICHIELS
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Untreated Control ◽  
Shigella Flexneri ◽  
Garden Cress ◽  
E Coli ◽  
Log Reduction ◽  
Gram Positive Bacteria ◽  
Sprout Length

Garden cress, sesame, radish, and mustard seeds immersed in water were treated with high pressure (250, 300, 350, and 400 MPa) for 15 min at 20°C. After treatment, percentages of seeds germinating on water agar were recorded for up to 11 days. Of the seeds tested, radish seeds were found to be the most pressure sensitive, with seeds treated at 250 MPa reaching 100% germination 9 days later than untreated control seeds did. Garden cress seeds, on the other hand, were the most pressure resistant, with seeds treated at 250 MPa reaching 100% germination 1 day later than untreated control seeds did. Garden cress sprouts from seeds treated at 250 and 300 MPa also took about 1 day longer to reach average sprout length than sprouts from untreated control seeds did, indicating that sprout growth was not retarded once germination had occurred. Garden cress seeds were inoculated with suspensions of seven different bacteria (107 CFU/ml) and processed with high pressure. Treatment at 300 MPa (15 min, 20°C) resulted in 6-log reductions of Salmonella Typhimurium, Escherichia coli MG1655, and Listeria innocua, &gt;4-log reductions of Shigella flexneri and pressure-resistant E. coli LMM1010, and a 2-log reduction of Staphylococcus aureus. Enterococcus faecalis was virtually not inactivated. For suspensions of the gram-positive bacteria, similar levels of inactivation in water in the absence of garden cress seeds were found, but the inactivation of E. coli LMM1010 and S. flexneri in water in the absence of garden cress seeds was significantly less extensive. These data suggest that garden cress seeds contain a component that acts synergistically with high hydrostatic pressure against gram-negative bacteria.

scholarly journals Stress-Induced Evolution of Heat Resistance and Resuscitation Speed in Escherichia coli O157:H7 ATCC 43888

2016 ◽  
Vol 82 (22) ◽  
pp. 6656-6663 ◽  
Author(s):  
Elisa Gayán ◽  
Alexander Cambré ◽  
Chris W. Michiels ◽  
Abram Aertsen
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Hydrostatic Pressure ◽  
Foodborne Pathogens ◽  
High Hydrostatic Pressure ◽  
Cross Resistance ◽  
Content Type ◽  
E Coli ◽  
Mild Heat ◽  
Mutant Strains

ABSTRACTThe development of resistance in foodborne pathogens to food preservation techniques is an issue of increasing concern, especially in minimally processed foods where safety relies on hurdle technology. In this context, mild heat can be used in combination with so-called nonthermal processes, such as high hydrostatic pressure (HHP), at lower individual intensities to better retain the quality of the food. However, mild stresses may increase the risk of (cross-)resistance development in the surviving population, which in turn might compromise food safety. In this investigation, we examined the evolution ofEscherichia coliO157:H7 strain ATCC 43888 after recurrent exposure to progressively intensifying mild heat shocks (from 54.0°C to 60.0°C in 0.5°C increments) with intermittent resuscitation and growth of survivors. As such, mutant strains were obtained after 10 cycles of selection with ca. 106-fold higher heat resistance than that for the parental strain at 58.0°C, although this resistance did not extend to temperatures exceeding 60.0°C. Moreover, these mutant strains typically displayed cross-resistance against HHP shock and displayed signs of enhanced RpoS and RpoH activity. Interestingly, additional cycles of selection maintaining the intensity of the heat shock constant (58.5°C) selected for mutant strains in which resuscitation speed, rather than resistance, appeared to be increased. Therefore, it seems that resistance and resuscitation speed are rapidly evolvable traits inE. coliATCC 43888 that can compromise food safety.IMPORTANCEIn this investigation, we demonstrated thatEscherichia coliO157:H7 ATCC 43888 rapidly acquires resistance to mild heat exposure, with this resistance yielding cross-protection to high hydrostatic pressure treatment. In addition, mutants ofE. coliATCC 43888 in which resuscitation speed, rather than resistance, appeared to be improved were selected. As such, both resistance and resuscitation speed seem to be rapidly evolvable traits that can compromise the control of foodborne pathogens in minimal processing strategies, which rely on the efficacy of combined mild preservation stresses for food safety.

scholarly journals Inactivation of Escherichia coli O157:H7 by High Hydrostatic Pressure Combined with Gas Packaging

2019 ◽  
Vol 7 (6) ◽  
pp. 154 ◽  
Author(s):  
Bing Zhou ◽  
Luyao Zhang ◽  
Xiao Wang ◽  
Peng Dong ◽  
Xiaosong Hu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Cellular Structure ◽  
Combined Treatment ◽  
Physiological Saline ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Significant Difference

The inactivation of Escherichia coli O157:H7 (E. coli) in physiological saline and lotus roots by high hydrostatic pressure (HHP) in combination with CO2 or N2 was studied. Changes in the morphology, cellular structure, and membrane permeability of the cells in physiological saline after treatments were investigated using scanning electron microscopy, transmission electron microscopy, and flow cytometry, respectively. It was shown that after HHP treatments at 150–550 MPa, CO2-packed E. coli cells had higher inactivation than the N2-packed and vacuum-packed cells, and no significant difference was observed in the latter two groups. Further, both the morphology and intracellular structure of CO2-packed E.coli cells were strongly destroyed by high hydrostatic pressure. However, serious damage to the intracellular structures occurred in only the N2-packed E. coli cells. During HHP treatments, the presence of CO2 caused more disruptions in the membrane of E. coli cells than in the N2-packed and vacuum-packed cells. These results indicate that the combined treatment of HHP and CO2 had a strong synergistic bactericidal effect, whereas N2 did not have synergistic effects with HHP. Although these two combined treatments had different effects on the inactivation of E. coli cells, the inactivation mechanisms might be similar. During both treatments, E. coli cells were inactivated by cell damage induced to the cellular structure through the membrane components and the extracellular morphology, unlike the independent HHP treatment.

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