Comparative Effect of Heat Shock on Survival of O157:H7 and Non-O157 Shiga Toxigenic Escherichia coli and Salmonella in Lean Beef with or without Moisture-Enhancing Ingredients

2017 ◽  
Vol 80 (6) ◽  
pp. 1002-1008 ◽  
Author(s):  
Akhila Vasan ◽  
Steven C. Ingham ◽  
Barbara H. Ingham
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Thermal Tolerance ◽  
Pathogenic Bacteria ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
Beef Industry ◽  
Linear Portion ◽  
Beef Products ◽  
Pathogen Control

ABSTRACT Thermal tolerance of pathogenic bacteria has been shown to increase after exposure to sublethal elevated temperatures, or heat shock. We evaluated the effect of heat shock at 48°C on thermal tolerance (D55°C) of cocktails of O157 and non-O157 Shiga toxigenic Escherichia coli (STEC) and Salmonella in lean ground beef with or without moisture-enhancing ingredients. Beef was moisture enhanced to 110% (w) with a 5% NaCl–2.5% sodium tripolyphosphate (w/w) brine. Meat, with or without added brine, was inoculated (∼108 CFU/g) and heat shocked at 48°C for 0, 5, or 30 min, followed by isothermal heating at 55°C. Inoculated control samples were unenhanced and were not subject to heat shock. From the linear portion of the log CFU per gram surviving cells over time plots, D55°C-values (minutes) were calculated. D55°C was 20.43, 28.78, and 21.15 min for O157, non-O157, and Salmonella controls, respectively. Overall, heat shock significantly increased D55°C, regardless of pathogen (P < 0.05). After 30 min of heat shock, D55°C increased 89 and 160% for O157 STEC, 32 and 49% for non-O157 STEC, and 29 and 57% for Salmonella, in unenhanced and enhanced samples, respectively, relative to the pathogen control. D55°C for Salmonella was the same or significantly less than for O157 and non-O157 STEC, regardless of heat shock, and was significantly less than for O157 and non-O157 STEC in all trials with moisture-enhanced meat (P < 0.05). Moisture-enhancing ingredients significantly increased D55°C, regardless of pathogen (P < 0.05). We suggest that thermal processes validated against Salmonella may not prove effective against STEC in all cases and that regulators of the beef industry should focus attention on STEC in nonintact moisture-enhanced beef products.

Prevalence of Shiga Toxin–Producing Escherichia coli in Beef Cattle

2005 ◽  
Vol 68 (10) ◽  
pp. 2224-2241 ◽  
Author(s):  
HUSSEIN S. HUSSEIN ◽  
LAURIE M. BOLLINGER
Keyword(s):  
Escherichia Coli ◽  
Beef Cattle ◽  
Hemolytic Uremic Syndrome ◽  
Health Risks ◽  
Shiga Toxin ◽  
Beef Industry ◽  
Potential Health ◽  
Cattle Feces ◽  
Beef Products ◽  
Uremic Syndrome

A large number of Shiga toxin–producing Escherichia coli (STEC) strains have caused major outbreaks and sporadic cases of human illnesses, including mild diarrhea, bloody diarrhea, hemorrhagic colitis, and the life-threatening hemolytic uremic syndrome. These illnesses have been traced to both O157 and non-O157 STEC. In a large number of STEC-associated outbreaks, the infections were attributed to consumption of ground beef or other beef products contaminated with cattle feces. Thus, beef cattle are considered reservoirs of STEC and can pose significant health risks to humans. The global nature of the human food supply suggests that safety concerns with beef will continue and the challenges facing the beef industry will increase at the production and processing levels. To be prepared to address these concerns and challenges, it is critical to assess the role of beef cattle in human STEC infections. In this review, published reports on STEC in beef cattle were evaluated to achieve the following specific objectives: (i) assess the prevalence of STEC in beef cattle, and (ii) determine the potential health risks of STEC strains from beef cattle. The latter objective is critically important because many beef STEC isolates are highly virulent. Global testing of beef cattle feces revealed wide ranges of prevalence rates for O157 STEC (i.e., 0.2 to 27.8%) and non-O157 STEC (i.e., 2.1 to 70.1%). Of the 261 STEC serotypes found in beef cattle, 44 cause hemolytic uremic syndrome and 37 cause other illnesses.

scholarly journals Elimination of Escherichia coli O157:H7 from Alfalfa Seeds through a Combination of High Hydrostatic Pressure and Mild Heat

2009 ◽  
Vol 75 (7) ◽  
pp. 1901-1907 ◽  
Author(s):  
Hudaa Neetoo ◽  
Thompson Pizzolato ◽  
Haiqiang Chen
Keyword(s):  
Escherichia Coli ◽  
Pathogenic Bacteria ◽  
Elevated Temperatures ◽  
Treatment Time ◽  
Seed Viability ◽  
Treatment Temperature ◽  
Reduced Pressure ◽  
Unique Challenge ◽  
Produce Safety ◽  
Alfalfa Seeds

ABSTRACT Escherichia coli O157:H7 has been associated with contaminated seed sprout outbreaks. The majority of these outbreaks have been traced to sprout seeds contaminated with low levels of pathogens. Sanitizing sprout seeds presents a unique challenge in the arena of produce safety in that even a low residual pathogen population remaining on contaminated seed after treatments appears capable of growing to very high levels during sprouting. In this study, the effectiveness of high-pressure treatment in combination with low and elevated temperatures was assessed for its ability to eliminate E. coli O157:H7 on artificially contaminated alfalfa seeds. Inoculated seed samples were treated at 600 MPa for 2 min at 4, 20, 25, 30, 35, 40, 45, and 50°C. The pressure sensitivity of the pathogenic bacteria was strongly dependent on the treatment temperature. At 40°C, the process was adequate in eliminating a 5-log-unit population on the seeds with no adverse effect on seed viability. Three treatments carried out at reduced pressure levels and/or extended treatment time, 550 MPa for 2 min at 40°C, 300 MPa for 2 min at 50°C, and 400 MPa for 5 min at 45°C, were equally lethal to the pathogen. When all three treatments were compared in terms of their impact on seed viability, the process of 550 MPa for 2 min at 40°C was the most desirable, achieving final germination percentages and sprout sizes statistically similar to those of control untreated seeds (P > 0.05).

Adaptation of Escherichia coli to elevated temperatures: The metA gene product is a heat shock protein

1990 ◽  
Vol 58 (3) ◽  
pp. 169-174 ◽  
Author(s):  
Eliora Z. Ron ◽  
Sari Alajem ◽  
Dvora Biran ◽  
Nili Grossman
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Gene Product ◽  
Elevated Temperatures

scholarly journals Specific and promiscuous functions of multiple DnaJ proteins in Synechocystis sp. PCC 6803

Microbiology ◽  
2011 ◽  
Vol 157 (5) ◽  
pp. 1269-1278 ◽  
Author(s):  
Eva Düppre ◽  
Eva Rupprecht ◽  
Dirk Schneider
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Domain Structure ◽  
Elevated Temperatures ◽  
Growth Defect ◽  
Gene Encoding ◽  
Encoding Gene ◽  
Synechocystis Sp ◽  
Pcc 6803

Cyanobacterial genomes typically encode multiple Hsp70 (DnaK) and Hsp40 (DnaJ) chaperones, and in the genome of the cyanobacterium Synechocystis PCC 6803, three DnaK proteins are encoded together with seven DnaJ proteins. While only two of the DnaJ proteins can complement the growth defect of an Escherichia coli ΔdnaJ strain, only disruption of the dnaJ gene sll0897 resulted in a growth defect at elevated temperatures. Based on the domain structure and the phenotype observed following disruption of the encoding gene, Sll0897 can be classified as a canonical heat-shock protein in Synechocystis. Furthermore, most dnaJ genes could be deleted individually, whereas disruption of the gene encoding the DnaJ Sll1933 failed, which suggests an essential, yet undefined, function for Sll1933. Since after deletion of the remaining dnaJ genes the phenotypes were not altered, the functions of these DnaJs either are not critical or are taken over by the remaining DnaJs. Nevertheless, only the two dnaJ genes sll0909 and sll1384 could be disrupted in combination, suggesting physiological functions for the two encoded proteins which either are not overlapping and/or can be fulfilled by the remaining DnaJs in the double-disruption strain. Taken together, the present analysis indicates specific and promiscuous functions for multiple DnaJ proteins in Synechocystis.

Thermal Inactivation Studies of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in Ready-to-Eat Chicken-Fried Beef Patties

2006 ◽  
Vol 69 (5) ◽  
pp. 1080-1086 ◽  
Author(s):  
T. OSAILI ◽  
C. L. GRIFFIS ◽  
E. M. MARTIN ◽  
B. L. BEARD ◽  
A. KEENER ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Pathogenic Bacteria ◽  
Thermal Inactivation ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Model Average ◽  
Beef Patties ◽  
Beef Products ◽  
D Values

Thermal inactivation studies were used to determine the D- and z-values of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in ready-to-eat chicken-fried beef patties. Inoculated meat was packaged in sterile bags, which were immersed in a circulated water bath and held at 55, 57.5, 60, 62.5, 65, 67.5, and 70°C for different lengths of time. D- and z-values were determined with a linear regression model. Average D-values at temperatures 55 to 70°C were 27.62 to 0.04 min for E. coli O157:H7, 67.68 to 0.22 min for Salmonella, and 81.37 to 0.31 min for L. monocytogenes. The z-values were 5.2°C for E. coli O157:H7, 6.0°C for Salmonella, and 6.1°C for L. monocytogenes. The results of this study can be used by food processors to validate their processes and help eliminate pathogenic bacteria associated with chicken-fried beef products.

Isolation of Epigallocatechin Gallate from Green Tea and its Effects on Probiotics and Pathogenic Bacteria

2017 ◽  
Vol 17 (1) ◽  
pp. 69-77
Author(s):  
Tu Lijun ◽  
Sun Hanju ◽  
He Shudong ◽  
Zhu Yongsheng ◽  
Yu Ming ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Escherichia Coli ◽  
Green Tea ◽  
Lactobacillus Acidophilus ◽  
Pathogenic Bacteria ◽  
Epigallocatechin Gallate ◽  
Microbial Populations ◽  
Medium Ph ◽  
Bioactive Substance ◽  
Tea Extract

The aim of this study was to investigate epigallocatechin gallate (EGCG) prebiotics activities systematically which was reported as a bioactive substance. Therefore, EGCG was separated by water extraction, resin purification and prep-HPLC. Then the production of EGCG was confirmed by HPLC and mass spectrometry (MS) analysis and its purify was 97.23%. EGCG extractive and green tea extract (GTE) were further incubated with Bifidobacterium infantis, B. adolescentis, B. bifidum and Lactobacillus acidophilus to study its effect on microbial populations and medium pH. Finally, Escherichia coli, Salmonella, Staphylococcus aureus and Candida albicans were employed as pathogenic bacteria to explore the antimicrobial activity of EGCG and GTE. The results demonstrated that EGCG extractive could be beneficial for the proliferation of Bifidobacterium and L. acidophilus and also inhibit some pathogenic bacteria. In conclusion, both EGCG extractive and GTE had prebiotics activities and the effects of EGCG extractive were superior to those of GTE.

Microbiological quality of residues from drinking water preparation

1995 ◽  
Vol 31 (5-6) ◽  
pp. 75-79 ◽  
Author(s):  
M. Würzer ◽  
A. Wiedenmann ◽  
K. Botzenhart
Keyword(s):  
Waste Water ◽  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Drinking Water ◽  
Water Treatment ◽  
Pathogenic Bacteria ◽  
Waste Water Treatment ◽  
Microbiological Quality ◽  
Detection Limits

In Germany the application of procedures such as flocculation and filtration in the preparation of drinking water results in the annual production of an estimated 500,000 t of sediments and sludges. Some of these residues have a potential for being reused, for example in agriculture, forestry, brickworks or waste water treatment. To assess the microbiological quality of residues from waterworks methods for the detection of enterobacteria, Escherichia coli, Salmonella, Pseudomonas aeruginosa, Legionella, poliovirus, Ascaris suis eggs and Cryptosporidium have been evaluated regarding their detection limits and were applied to various residues from German waterworks. Results show that sediments and sludges may contain pathogenic bacteria, viruses and protista. When residues from waterworks are intended to be reused in agriculture or forestry the microbiological quality should therefore be considered.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

Expression and characterization of an α-glucosidase from Thermoanaerobacter ethanolicus JW200 with potential for industrial application

Biologia ◽  
2009 ◽  
Vol 64 (6) ◽  
Author(s):  
Yue-Hong Wang ◽  
Yu Jiang ◽  
Zuo-Ying Duan ◽  
Wei-Lan Shao ◽  
Hua-Zhong Li
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Optimal Condition ◽  
Industrial Application ◽  
Conversion Rate ◽  
Hydrolytic Activity ◽  
Thermoanaerobacter Ethanolicus ◽  
Transglycosylation Activity

AbstractIn this study, a new α-glucosidase gene from Thermoanaerobacter ethanolicus JW200 was cloned and expressed in Escherichia coli by a novel heat-shock vector pHsh. The recombinant α-glucosidase exhibited its maximum hydrolytic activity at 70°C and pH 5.0∼5.5. With p-nitrophenyl-α-D-glucoside as a substrate and under the optimal condition (70°C, pH 5.5), K m and V max of the enzyme was 1.72 mM and 39 U/mg, respectively. The purified α-glucosidase could hydrolyze oligosaccharides with both α-1,4 and α-1,6 linkages. The enzyme also had strong transglycosylation activity when maltose was used as sugar donor. The transglucosylation products towards maltose are isomaltose, maltotriose, panose, isomaltotriose and tetrasaccharides. The enzyme could convert 400 g/L maltose to oligosaccharides with a conversion rate of 52%, and 83% of the oligosaccharides formed were prebiotic isomaltooligosaccharides (containing isomaltose, panose and isomaltotriose).

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