UV Tolerance of Spoilage Microorganisms and Acid-Shocked and Acid-Adapted Escherichia coli in Apple Juice Treated with a Commercial UV Juice-Processing Unit

2016 ◽  
Vol 79 (2) ◽  
pp. 294-298 ◽  
Author(s):  
JESSIE USAGA ◽  
OLGA I. PADILLA-ZAKOUR ◽  
RANDY W. WOROBO
Keyword(s):  
Escherichia Coli ◽  
Apple Juice ◽  
Safety Concern ◽  
Physiological State ◽  
Processing Unit ◽  
Pathogen Inactivation ◽  
E Coli ◽  
Uv Sensitivity ◽  
Uv Tolerance ◽  
Spoilage Microorganisms

ABSTRACT The enhanced thermal tolerance and survival responses of Escherichia coli O157:H7 in acid and acidified foods is a major safety concern for the production of low-pH products, including beverages. Little is known about this phenomenon when using UV light treatments. This study was conducted to evaluate the effects of strain (E. coli O157:H7 strains C7927, ATCC 35150, ATCC 43895, and ATCC 43889 and E. coli ATCC 25922) and physiological state (control-unadapted, acid adapted, and acid shocked) on the UV tolerance of E. coli in apple juice treated under conditions stipulated in current U.S. Food and Drug Administration regulations. A greater than 5-log reduction of E. coli was obtained under all tested conditions. A significant effect of strain (P < 0.05) was observed, but the physiological state did not influence pathogen inactivation (P ≥ 0.05). The UV sensitivity of three spoilage microorganisms (Aspergillus niger, Penicillium commune, and Alicyclobacillus acidoterrestris) was also determined at UV doses of 0 to 98 mJ/cm2. Alicyclobacillus was the most UV sensitive, followed by Penicillium and Aspergillus. Because of the nonsignificant differences in UV sensitivity of E. coli in different physiological states, the use of an unadapted inoculum would be adequate to conduct challenge studies with the commercial UV unit used in this study at a UV dose of 14 mJ/cm2. The high UV tolerance of spoilage microorganisms supports the need to use a hurdle approach (e.g., coupling of refrigeration, preservatives, and/or other technologies) to extend the shelf life of UV-treated beverages.

Effect of Acid Adaptation and Acid Shock on Thermal Tolerance and Survival of Escherichia coli O157:H7 and O111 in Apple Juice

2014 ◽  
Vol 77 (10) ◽  
pp. 1656-1663 ◽  
Author(s):  
JESSIE USAGA ◽  
RANDY W. WOROBO ◽  
OLGA I. PADILLA-ZAKOUR
Keyword(s):  
Escherichia Coli ◽  
Thermal Tolerance ◽  
Significant Interaction ◽  
Apple Juice ◽  
Storage Temperature ◽  
Physiological State ◽  
Escherichia Coli O157 ◽  
Decimal Reduction Time ◽  
E Coli ◽  
Acid Shock

Gradual exposure to moderate acidic environments may enhance the thermal tolerance and survival of Escherichia coli O157:H7 in acid and acidified foods. Limited studies comparing methodologies to induce this phenomenon have been performed. The effects of strain and physiological state on thermal tolerance and survival of E. coli in apple juice were studied. The decimal reduction time (D-value) at 56°C [D56°C] was determined for E. coli O157:H7 strains C7927 and ATCC 43895 and E. coli O111 at four physiological states: unadapted, acid-shocked (two methodologies used), and acid-adapted cells. The effect of acidulant was also evaluated by determining the D56°C for the O157:H7 strains subjected to acid shock during 18 h in Trypticase soy broth (TSB), with pH 5 adjusted with hydrochloric, lactic, and malic acids. Survival of the three strains at four physiological states was determined at 1 ± 1°C and 24 + 2°C. Experiments were performed in triplicate. For thermal inactivation, a significant interaction was found between strain and physiological state (P < 0.0001). Highest thermal tolerance was observed for the 43895 strain subjected to acid shock during 18 h in TSB acidified with HCl (D56°C of 3.0 ± 0.1 min) and the lowest for the acid-shocked C7927 strain treated for 4 h in TSB acidified with HCl (D56°C of 0.45 ± 0.06 min). Acidulants did not alter the heat tolerance of strain C7927 (D56°C of 1.9 ± 0.1 min; P > 0.05) but significantly affected strain 43895 (P < 0.05), showing the greatest tolerance when malic acid was used (D56°C of 3.7 ± 0.3 min). A significant interaction between strain, storage temperature, and physiological state was noted during the survival experiments (P < 0.05). E. coli O111 was the most resistant strain, surviving 6 and 23 days at 24 and 1°C, respectively. Our findings may assist in designing challenge studies for juices and other pH-controlled products, where Shiga toxin–producing E. coli represents the pathogen of concern.

Introduction to the Food Safety Concerns of Verotoxin-Producing Escherichia coli

2003 ◽  
Vol 228 (4) ◽  
pp. 331-332 ◽  
Author(s):  
Hussein S. Hussein ◽  
Stanley T. Omaye
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Safety Concern ◽  
Critical Evaluation ◽  
The United States ◽  
Global Perspective ◽  
E Coli ◽  
The Past ◽  
Food Borne Pathogens ◽  
Food Borne

Verotoxin-producing Escherichia coli (VTEC) have emerged in the past two decades as food-borne pathogens that can cause major outbreaks of human illnesses worldwide. The number of outbreaks has increased in recent years due to changes in food production and processing systems, eating habits, microbial adaptation, and methods of VTEC transmission. The human illnesses range from mild diarrhea to hemolytic uremic syndrome (HUS) that can lead to death. The VTEC outbreaks have been attributed to O157:H7 and non-O157:H7 serotypes of E. coli. These E. coli serotypes include motile (e.g., O26:H11 and O104:H21) and nonmotile (e.g., O111:H–,0145:H–, and O157:H–) strains. In the United States, E. coli O157:H7 has been the major cause of VTEC outbreaks. Worldwide, however, non-O157:H7 VTEC (e.g., members of the 026, O103, O111, O118, O145, and O166 serogroups) have caused approximately 30% of the HUS cases in the past decade. Because large numbers of the VTEC outbreaks have been attributed to consumption of ruminant products (e.g., ground beef), cattle and sheep are considered reservoirs of these food-borne pathogens. Because of the food safety concern of VTEC, a global perspective on this problem is addressed (Exp Biol Med Vol. 228, No. 4). The first objective was to evaluate the known non-O157:H7 VTEC strains and the limitations associated with their detection and characterization. The second objective was to identify the VTEC serotypes associated with outbreaks of human illnesses and to provide critical evaluation of their virulence. The third objective was to determine the rumen effect on survival of E. coli O157:H7 as a VTEC model. The fourth objective was to explore the role of intimins in promoting attaching and effacing lesions in humans. Finally, the ability of VTEC to cause persistent infections in cattle was evaluated.

Antibacterial Effect of Monocaprylin on Escherichia coli O157:H7 in Apple Juice

2005 ◽  
Vol 68 (9) ◽  
pp. 1895-1899 ◽  
Author(s):  
MANOJ KUMAR MOHAN NAIR ◽  
HANEM ABOUELEZZ ◽  
THOMAS HOAGLAND ◽  
KUMAR VENKITANARAYANAN
Keyword(s):  
Escherichia Coli ◽  
Apple Juice ◽  
Antibacterial Effect ◽  
Storage Temperature ◽  
Escherichia Coli O157 ◽  
Organoleptic Properties ◽  
E Coli ◽  
Low Concentrations ◽  
Storage Temperatures ◽  
Control Samples

The antibacterial effect of low concentrations of monocaprylin on Escherichia coli O157:H7 in apple juice was investigated. Apple juice alone (control) or containing 2.5 mM (0.055%) or 5 mM monocaprylin was inoculated with a five-strain mixture of E. coli O157:H7 at ~6.0 log CFU/ml. The juice samples were stored at 23 or 4°C for 14 or 21 days, respectively, and the population of E. coli O157:H7 was determined on tryptic soy agar plates supplemented with 0.6% yeast extract. At both storage temperatures, the population of E. coli O157:H7 in monocaprylin-supplemented juice samples was significantly lower (P < 0.05) than that in the control samples. The concentration of monocaprylin and the storage temperature had a significant effect on the inactivation of E. coli O157:H7 in apple juice. Monocaprylin at 5 mM was significantly more effective than 2.5 mM monocaprylin for killing E. coli O157:H7 in apple juice. Inactivation of E. coli O157:H7 by monocaprylin was more pronounced in juice stored at 23°C than in the refrigerated samples. Results of this study indicated that monocaprylin is effective for killing E. coli O157:H7 in apple juice, but detailed sensory studies are needed to determine the organoleptic properties of apple juice containing monocaprylin.

Inactivation of Escherichia coli O157:H7 in Nonintact Beefsteaks of Different Thicknesses Cooked by Pan Broiling, Double Pan Broiling,or Roasting by Using Five Types of Cooking Appliances

2010 ◽  
Vol 73 (3) ◽  
pp. 461-469 ◽  
Author(s):  
CANGLIANG SHEN ◽  
JEREMY M. ADLER ◽  
IFIGENIA GEORNARAS ◽  
KEITH E. BELK ◽  
GARY C. SMITH ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Thermal Inactivation ◽  
Sodium Tripolyphosphate ◽  
Cooking Methods ◽  
Escherichia Coli O157 ◽  
Target Temperature ◽  
Pathogen Inactivation ◽  
Total Water ◽  
E Coli ◽  
George Foreman

This study compared thermal inactivation of Escherichia coli O157:H7 in nonintact beefsteaks of different thicknesses by different cooking methods and appliances. Coarsely ground beef was inoculated with rifampin-resistant E. coli O157:H7 (eight-strain composite, 6 to 7 log CFU/g) and then mixed with sodium chloride (0.45%) plus sodium tripolyphosphate (0.23%); the total water added was 10%. The meat was stuffed into bags (10-cm diameter), semifrozen (−20°C, 6 h), and cut into 1.5-, 2.5-, and 4.0-cm-thick steaks. Samples were then individually vacuum packaged, frozen (−20°C, 42 h), and tempered (4°C, 2.5 h) before cooking. Partially thawed (−2 ± 1°C) steaks were pan broiled (Presto electric skillet and Sanyo grill), double pan broiled (George Foreman grill), or roasted (Oster toaster oven and Magic Chef standard kitchen oven) to a geometric center temperature of 65°C. Extent of pathogen inactivation decreased in order of roasting (2.0 to 4.2 log CFU/g) > pan broiling (1.6 to 2.8 log CFU/g) ≥ double pan broiling (1.1 to 2.3 log CFU/g). Cooking of 4.0-cm-thick steaks required a longer time (19.8 to 65.0 min; variation was due to different cooking appliances), and caused greater reductions in counts (2.3 to 4.2 log CFU/g) than it did in thinner samples (1.1 to 2.9 log CFU/g). The time to reach the target temperature increased in order of George Foreman grill (3.9 to 19.8 min) < Oster toaster oven (11.3 to 45.0 min) < Presto electric skillet (16.3 to 55.0 min) < Sanyo grill (14.3 to 65.0 min) < standard kitchen oven (20.0 to 63.0 min); variation was due to steak thickness. Results indicated that increased steak thickness allowed greater inactivation of E. coli O157:H7, as time to reach the target internal temperature increased. Roasting in a kitchen oven was most effective for pathogen inactivation.

Ammonia sanitization of blackwater for safe use as fertilizer

2015 ◽  
Vol 71 (5) ◽  
pp. 795-800 ◽  
Author(s):  
Jörgen Fidjeland ◽  
Sven-Erik Svensson ◽  
Björn Vinnerås
Keyword(s):  
Escherichia Coli ◽  
Treatment Time ◽  
Escherichia Coli O157 ◽  
Storage Facility ◽  
Egg Viability ◽  
Pathogen Inactivation ◽  
E Coli ◽  
Available Nutrients ◽  
Manure Slurry ◽  
The Impact

Source-separated blackwater from low-flush toilets contains plant-available nutrients and can be used as a fertilizer. The aim of the study was to evaluate the impact on pathogen inactivation when treating blackwater with urea and/or lime. Blackwater was spiked with Salmonella typhimurium, Escherichia coli O157, Enterococcus faecalis, and Ascaris suum eggs, and treated with urea and/or lime in concentrations up to 0.1% w/w. The bottles were kept in a storage facility (manure slurry tank) for 102 days while monitoring the pathogen concentrations. The treatment time needed to meet the requirement for Salmonella and E. coli reduction could be reduced at least six-fold. The enterococci were more persistent, and only the highest treatment doses had a significantly higher inactivation than the controls. The Ascaris egg viability was only reduced by around 50%, so higher urea/lime doses and/or longer treatment times are required to fulfill the treatment requirements of 3 log10 reductions of parasite eggs.

scholarly journals AnEscherichia colinitrogen starvation response is important for mutualistic coexistence withRhodopseudomonas palustris

2018 ◽  
Author(s):  
Alexandra L. McCully ◽  
Megan G. Behringer ◽  
Jennifer R. Gliessman ◽  
Evgeny V. Pilipenko ◽  
Jeffrey L. Mazny ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Nitrogen Starvation ◽  
Physiological State ◽  
Rhodopseudomonas Palustris ◽  
Genetically Engineered ◽  
Individual Species ◽  
Starvation Response ◽  
E Coli ◽  
Protein Levels ◽  
Stable Coexistence

AbstractMicrobial mutualistic cross-feeding interactions are ubiquitous and can drive important community functions. Engaging in cross-feeding undoubtedly affects the physiology and metabolism of individual species involved. However, the nature in which an individual’s physiology is influenced by cross-feeding and the importance of those physiological changes for the mutualism have received little attention. We previously developed a genetically tractable coculture to study bacterial mutualisms. The coculture consists of fermentativeEscherichia coliand phototrophicRhodopseudomonas palustris. In this coculture, E. coli anaerobically ferments sugars into excreted organic acids as a carbon source for R. palustris. In return, a genetically-engineered R. palustris constitutively converts N2into NH4+, providingE. coliwith essential nitrogen. Using RNA-seq and proteomics, we identified transcript and protein levels that differ in each partner when grown in coculture versus monoculture. When in coculture withR. palustris, E. coligene-expression changes resembled a nitrogen starvation response under the control of the transcriptional regulator NtrC. By genetically disruptingE. coliNtrC, we determined that a nitrogen starvation response is important for a stable coexistence, especially at lowR. palustrisNH4+excretion levels. Destabilization of the nitrogen starvation regulatory network resulted in variable growth trends and in some cases, extinction. Our results highlight that alternative physiological states can be important for survival within cooperative cross-feeding relationships.ImportanceMutualistic cross-feeding between microbes within multispecies communities is widespread. Studying how mutualistic interactions influence the physiology of each species involved is important for understanding how mutualisms function and persist in both natural and applied settings. Using a bacterial mutualism consisting ofRhodopseudomonas palustrisandEscherichia coligrowing cooperatively through bidirectional nutrient exchange, we determined that anE. colinitrogen starvation response is important for maintaining a stable coexistence. The lack of anE. colinitrogen starvation response ultimately destabilized the mutualism and, in some cases, led to community collapse after serial transfers. Our findings thus inform on the potential necessity of an alternative physiological state for mutualistic coexistence with another species compared to the physiology of species grown in isolation.

Inactivation of Escherichia coli O157:H7 in Apple Juice by Irradiation

1998 ◽  
Vol 64 (11) ◽  
pp. 4533-4535 ◽  
Author(s):  
R. L. Buchanan ◽  
S. G. Edelson ◽  
K. Snipes ◽  
G. Boyd
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Radiation Resistance ◽  
Apple Juice ◽  
Suspended Solids ◽  
Acid Resistance ◽  
E Coli ◽  
Cesium 137 ◽  
Microbiological Criteria ◽  
Ph Dependent

ABSTRACT Three strains (932, Ent-C9490, and SEA13B88) of Escherichia coli O157:H7 were used to determine the effectiveness of low-dose gamma irradiation for eliminating E. coli O157:H7 from apple juice or cider and to characterize the effect of inducing pH-dependent, stationary-phase acid resistance on radiation resistance. The strains were grown in tryptic soy broth with or without 1% dextrose for 18 h to produce cells that were or were not induced to pH-dependent stationary-phase acid resistance. The bacteria were then transferred to clarified apple juice and irradiated at 2°C with a cesium-137 irradiator. Non-acid-adapted cells had radiationD values (radiation doses needed to decrease a microbial population by 90%) ranging from 0.12 to 0.21 kGy. D values increased to 0.22 to 0.31 kGy for acid-adapted cells. When acid-adapted SEA13B88 cells were tested in five apple juice brands having different levels of suspended solids (absorbances ranging from 0.04 to 2.01 at 550 nm), radiation resistance increased with increasing levels of suspended solids, with D values ranging from 0.26 to 0.35 kGy. Based on these results, a dose of 1.8 kGy should be sufficient to achieve the 5D inactivation of E. colirecommended by the National Advisory Committee for Microbiological Criteria for Foods.

Validation of the Thermo Scientific SureTect Escherichia coli O157:H7 Real-Time PCR Assay for Raw Beef and Produce Matrixes

2015 ◽  
Vol 98 (5) ◽  
pp. 1301-1314 ◽  
Author(s):  
Jonathan Cloke ◽  
Erin Crowley ◽  
Patrick Bird ◽  
Ben Bastin ◽  
Jonathan Flannery ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Real Time ◽  
Real Time Pcr ◽  
Apple Juice ◽  
Ground Beef ◽  
Reference Method ◽  
Escherichia Coli O157 ◽  
Pcr Assay ◽  
E Coli

Abstract The Thermo Scientific™ SureTect™ Escherichia coli O157:H7 Assay is a new real-time PCR assay which has been validated through the AOAC Research Institute (RI) Performance Tested MethodsSM program for raw beef and produce matrixes. This validation study specifically validated the assay with 375 g 1:4 and 1:5 ratios of raw ground beef and raw beef trim in comparison to the U.S. Department of Agriculture, Food Safety Inspection Service, Microbiology Laboratory Guidebook (USDS-FSIS/MLG) reference method and 25 g bagged spinach and fresh apple juice at a ratio of 1:10, in comparison to the reference method detailed in the International Organization for Standardization 16654:2001 reference method. For raw beef matrixes, the validation of both 1:4 and 1:5 allows user flexibility with the enrichment protocol, although which of these two ratios chosen by the laboratory should be based on specific test requirements. All matrixes were analyzed by Thermo Fisher Scientific, Microbiology Division, Vantaa, Finland, and Q Laboratories Inc, Cincinnati, Ohio, in the method developer study. Two of the matrixes (raw ground beef at both 1:4 and 1:5 ratios) and bagged spinach were additionally analyzed in the AOAC-RI controlled independent laboratory study, which was conducted by Marshfield Food Safety, Marshfield, Wisconsin. Using probability of detection statistical analysis, no significant difference was demonstrated by the SureTect kit in comparison to the USDA FSIS reference method for raw beef matrixes, or with the ISO reference method for matrixes of bagged spinach and apple juice. Inclusivity and exclusivity testing was conducted with 58 E. coli O157:H7 and 54 non-E. coli O157:H7 isolates, respectively, which demonstrated that the SureTect assay was able to detect all isolates of E. coli O157:H7 analyzed. In addition, all but one of the nontarget isolates were correctly interpreted as negative by the SureTect Software. The single isolate giving a positive result was an E. coli O157:NM isolate. Nonmotile isolates of E. coli O157 have been demonstrated to still contain the H7 gene; therefore, this result is not unexpected. Robustness testing was conducted to evaluate the performance of the SureTect assay with specific deviations to the assay protocol, which were outside the recommended parameters and which are open to variation. This study demonstrated that the SureTect assay gave reliable performance. A final study to verify the shelf life of the product, under accelerated conditions was also conducted.

Thermal Resistance Parameters for Shiga Toxin–Producing Escherichia coli in Apple Juice

2011 ◽  
Vol 74 (8) ◽  
pp. 1231-1237 ◽  
Author(s):  
ELENA ENACHE ◽  
EMILY C. MATHUSA ◽  
PHILIP H. ELLIOTT ◽  
D. GLENN BLACK ◽  
YUHUAN CHEN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Heat Resistance ◽  
Shiga Toxin ◽  
Resistant Strain ◽  
Apple Juice ◽  
E Coli ◽  
C Value ◽  
D Values ◽  
The Individual

The purpose of the present study was to determine the heat resistance of six non-O157 Shiga toxin–producing Escherichia coli (STEC) serotypes in comparison to E. coli O157:H7 in single-strength apple juice without pulp. The thermal parameters for stationary-phase and acid-adapted cells of E. coli strains from serogroups O26, O45, O103, O111, O121, O145, and O157:H7 were determined by using an immersed coil apparatus. The most heat-sensitive serotype in the present study was O26. Stationary-phase cells for serotypes O145, O121, and O45 had the highest D56°C-value among the six non-O157 serotypes studied, although all were significantly lower (P < 0.05) than that of E. coli O157:H7. At 60°C E. coli O157:H7 and O103 demonstrated the highest D-values (1.37 ± 0.23 and 1.07 ± 0.03 min, respectively). The D62°C for the most heat-resistant strain belonging to the serotype O145 was similar (P > 0.05) to that for the most resistant O157:H7 strain (0.61 ± 0.17 and 0.60 ± 0.09 min, respectively). The heat resistance for stationary-phase cells was generally equal to or higher than that of acid-adapted counterparts. Although E. coli O157:H7 revealed D-values similar to or higher than the individual six non-O157 STEC serotypes in apple juice, the z-values for most non-O157 STEC tested strains were greater than those of E. coli O157:H7. When data were used to calculate heat resistance parameters at a temperature recommended in U.S. Food and Drug Administration guidance to industry, the D71.1°C for E. coli O157:H7 and non-O157 STEC serotypes were not significantly different (P > 0.05).

scholarly journals Detection of Escherichia coli Serogroups O26 and O113 by PCR Amplification of the wzx and wzy Genes

2004 ◽  
Vol 70 (3) ◽  
pp. 1830-1832 ◽  
Author(s):  
Chitrita DebRoy ◽  
Elisabeth Roberts ◽  
James Kundrat ◽  
Michael A. Davis ◽  
Connie E. Briggs ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Apple Juice ◽  
Pcr Amplification ◽  
Environmental Microbiology ◽  
E Coli ◽  
O Antigen ◽  
Specific Pcr ◽  
Pcr Assays ◽  
Concentration Levels

ABSTRACT PCR-based assays for detecting enterohemorrhagic Escherichia coli serogroups O26 and O113 were developed by targeting the wzx (O-antigen flippase) and the wzy (O-antigen polymerase) genes found in the O-antigen gene cluster of each organism. The PCR assays were specific for the respective serogroups, as there was no amplification of DNA from non-O26 and non-O113 E. coli serogroups or from other bacterial genera tested. Using the PCR assays, we were able to detect the organisms in seeded apple juice inoculated at concentration levels as low as ≤10 CFU/ml. The O26- and O113-specific PCR assays can potentially be used for typing E. coli O26 and O113 serogroups; these assays will offer an advantage to food and environmental microbiology laboratories in terms of identifying these non-O157 serogroups by replacing antigen-based serotyping.

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