Survival of Escherichia coli after Isoelectric Solubilization and Precipitation of Fish Protein

2009 ◽  
Vol 72 (7) ◽  
pp. 1398-1403 ◽  
Author(s):  
L. R. LANSDOWNE ◽  
S. BEAMER ◽  
J. JACZYNSKI ◽  
K. E. MATAK
Keyword(s):  
Escherichia Coli ◽  
Recovery Process ◽  
Alkaline Treatment ◽  
Insoluble Fraction ◽  
Microbial Reduction ◽  
Protein Recovery ◽  
Protein Solution ◽  
Initial Inoculum ◽  
E Coli ◽  
Log Reduction

Protein recovery for fish processing by-products utilizes extreme pH shifts for isoelectric solubilization and precipitation. The purpose of this study was to determine if Escherichia coli would survive exposure to the extreme pH shifts during the protein recovery process. Fresh rainbow trout were beheaded, gutted, and minced and then inoculated with approximately 109 CFU of E. coli ATCC 25922 per g, homogenized, and brought to the target pH of 2.0, 3.0, 11.5, or 12.5 by the addition of concentrated hydrochloric acid or sodium hydroxide to solubilize muscle proteins. The homogenate was blended and centrifuged to separate the lipid and insoluble components (bones, skin, insoluble protein, etc.) from the protein solution. The protein solution was subjected to a second pH shift (pH 5.5) resulting in protein precipitation that was recovered with centrifugation. Microbial analysis was conducted on each fraction (i.e., lipid, insoluble components, protein, and water) with selective and nonselective media. The sums of the surviving E. coli in these fractions were compared with the initial inoculum. The greatest total microbial reduction occurred when the pH was shifted to 12.5 (P < 0.05), i.e., a 4.4-log reduction of cells on nonselective media and a 6.0-log reduction of cells on selective media. The use of selective and nonselective media showed that there was significant (P < 0.05) injury sustained by cells exposed to alkaline treatment (pH 11.5 and 12.5) in all fractions except the insoluble fraction at pH 11.5. Increasing the exposure time or the pH may result in greater bacterial reductions in the recovered protein.

Antibacterial Efficacy of Commonly Available Alcohol-Based Hand Sanitizers on Escherichia Coli

2020 ◽  
Vol 31 (2) ◽  
pp. 22-32
Author(s):  
Josephat S. Hema ◽  
Doreen A. Mloka ◽  
George M. Bwire ◽  
Ezekiel M. Marandu ◽  
Kennedy D. Mwambete
Keyword(s):  
Escherichia Coli ◽  
Dar Es Salaam ◽  
Reduction Factor ◽  
Microbial Reduction ◽  
Antibacterial Efficacy ◽  
E Coli ◽  
Log Reduction ◽  
Life Years ◽  
En 1500

Background: The WHO estimates that approximately 600 million people fall ill after consumption of contaminated food and over 420 000 die every year, resulting in loss of 33 million healthy life years. Hand hygiene is considered by the WHO to be the most effective preventive measure for infectious diseases including food borne diseases.Methods: A laboratory-based study involving convenient sampling of common brands alcohol-based hand sanitizers (ABHS) from retail community pharmacies and local supermarkets was conducted in Ilala District, Dar es salaam, Tanzania. The study was conducted, between December 2018 to January 2019. A modified protocol of The European Norm (EN) 1500 was used for in vivo testing of sampled ABHs. Efficacy was evaluated using standard strain of Escherichia coli. A total of 26 healthy volunteers were used for hand sanitization. The percentage of bioburden/microbial reduction was assessed at baseline and after treatment, and the log reduction factor calculated.Results: A total of 10 gel ABHS were purchased and assayed for antibacterial efficacy. Majority (70%) of ABHS were imported products and contained ethanol as the sole active ingredient. About 60% of them did not correctly indicate the label disclosure information on concentration of active ingredients. Only one product was efficacious against E. coli with log reduction of 3.75; while majority (70%) of the samples had poor bacterial efficacy with log reduction ranging from 0.140 -0.664.Conclusions: Most of ABHS gel products available in the Dar es Salaam market were not efficacious as per FDA and EN 1500 guidelines. Post market surveillance is recommended of the circulating ABH to safe guard consumers. Keywords: Hand sanitizers, efficacy, E. coli, EN 1500.

Evaluation of Bactericidal Effects of Phenyllactic Acid on Escherichia coli O157:H7 and Salmonella Typhimurium on Beef Meat

2019 ◽  
Vol 82 (12) ◽  
pp. 2016-2022
Author(s):  
RUISHENG ZHENG ◽  
TONG ZHAO ◽  
YEN-CON HUNG ◽  
KOUSHIK ADHIKARI
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Salmonella Typhimurium ◽  
Microbial Reduction ◽  
Escherichia Coli O157 ◽  
Phenyllactic Acid ◽  
E Coli ◽  
Log Reduction ◽  
Beef Meat ◽  
Bactericidal Effects

ABSTRACT Bactericidal effects of various concentrations of phenyllactic acid on Shiga toxin–producing Escherichia coli (STEC), including E. coli O157:H7, O26:H11, O103:H2, and O121:H19, and on Salmonella Typhimurium DT104 in pure culture and microplates assays were studied. Beef cuts were surface sprayed with phenyllactic acid or lactic acid for inactivation of E. coli O157:H7 and Salmonella Typhimurium. The 1.5% phenyllactic acid inactivated all inoculated E. coli O157:H7, O26:H11, O103:H2, and O121:H19 and Salmonella Typhimurium DT104 (>6-log reduction) within 1 min of contact at 21°C, whereas 1.5% lactic acid did not result in microbial reduction. Microplate assays (for STEC and Salmonella Typhimurium DT104 at 10 to 100 CFU per well) indicated that concentrations of 0.25% phenyllactic acid or 0.25% lactic acid inhibited the growth of STEC and Salmonella Typhimurium DT104 incubated at 37°C for 24 h. Treatment of beef with 1.5% lactic acid or 1.5% phenyllactic acid reduced E. coli O157:H7 by 0.22 and 0.38 log CFU/cm2, respectively, within 5 min and reduced Salmonella Typhimurium DT104 by 0.12 and 0.86 log CFU/cm2, respectively. When meat treated with 1.5% phenyllactic acid was frozen at −20°C, inactivation of E. coli O157 and Salmonella Typhimurium DT104 was enhanced by 1.06 and 1.46 log CFU/cm2, respectively. Thus, treatment of beef with 1.5% phenyllactic acid significantly reduced the population of E. coli O157:H7 and Salmonella. HIGHLIGHTS

Survival of Salmonella and Escherichia coli O157:H7 on Strawberries, Basil, and Other Leafy Greens during Storage

2015 ◽  
Vol 78 (4) ◽  
pp. 652-660 ◽  
Author(s):  
STEFANIE DELBEKE ◽  
SIELE CEUPPENS ◽  
LIESBETH JACXSENS ◽  
MIEKE UYTTENDAELE
Keyword(s):  
Escherichia Coli ◽  
Limit Of Detection ◽  
Escherichia Coli O157 ◽  
Similar Reduction ◽  
Initial Inoculum ◽  
E Coli ◽  
Log Reduction ◽  
Leafy Greens ◽  
Fresh Cut ◽  
Butterhead Lettuce

The survival of Salmonella and Escherichia coli O157:H7 on strawberries, basil leaves, and other leafy greens (spinach leaves, lamb and butterhead lettuce leaves, baby leaves, and fresh-cut iceberg lettuce) was assessed at cold (<7°C) and ambient temperatures. All commodities were spot inoculated with E. coli O157:H7 or Salmonella to obtain an initial inoculum of 5 to 6 log and 4 to 5 log CFU/g for strawberries and leafy greens, respectively. Samples were air packed. Strawberries were stored at 4, 10, 15, and 22°C and basil leaves and other leafy greens at 7, 15, and 22°C for up to 7 days (or less if spoiled before). Both Salmonella and E. coli O157:H7 showed a gradual decrease in numbers if inoculated on strawberries, with a similar reduction observed at 4, 10, and 15°C (2 to 3 log after 5 days). However, at 15°C (and 10°C for E. coli O157:H7), the survival experiment stopped before day 7, as die-off of both pathogens below the lower limit of detection was achieved or spoilage occurred. At 22°C, strawberries were moldy after 2 or 4 days. At that time, a 1- to 2-log reduction of both pathogens had occurred. A restricted die-off (on average 1.0 log) and increase (on average <0.5 log) of both pathogens on basil leaves occurred after 7 days of storage at 7 and 22°C, respectively. On leafy greens, a comparable decrease as on basil was observed after 3 days at 7°C. At 22°C, both pathogens increased to higher numbers on fresh-cut iceberg and butterhead lettuce leaves (on average 1.0 log), probably due to the presence of exudates. However, by using spot inoculation, the increase was rather limited, probably due to minimized contact between the inoculum and cell exudates. Avoiding contamination, in particular, at cultivation (and harvest or postharvest) is important, as both pathogens survive during storage, and strawberries, basil, and other leafy green leaves are consumed without inactivation treatment.

Reduction of Escherichia coli O157:H7 Counts on Whole Fresh Apples by Treatment with Sanitizers

2000 ◽  
Vol 63 (6) ◽  
pp. 703-708 ◽  
Author(s):  
MARCY A. WISNIEWSKY ◽  
BONITA A. GLATZ ◽  
MARK L. GLEASON ◽  
CHERYLL A. REITMEIER
Keyword(s):  
Escherichia Coli ◽  
Chlorine Dioxide ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Escherichia Coli O157 ◽  
Peroxyacetic Acid ◽  
Water Control ◽  
Buffer Solution ◽  
E Coli ◽  
Log Reduction

The objectives of this study were to determine if washing of whole apples with solutions of three different sanitizers (peroxyacetic acid, chlorine dioxide, or a chlorine-phosphate buffer solution) could reduce a contaminating nonpathogenic Escherichia coli O157:H7 population by 5 logs and at what sanitizer concentration and wash time such a reduction could be achieved. Sanitizers were tested at 1, 2, 4, 8, and 16 times the manufacturer's recommended concentration at wash times of 5, 10, and 15 min. Whole, sound Braeburn apples were inoculated with approximately 1 × 108 or 7 × 106 CFU per apple, stored for 24 h, then washed with sterile water (control) or with sanitizers for the prescribed time. Recovered bacteria were enumerated on trypticase soy agar. Washing with water alone reduced the recoverable population by almost 2 logs from the starting population; this can be attributed to physical removal of organisms from the apple surface. No sanitizer, when used at the recommended concentration, reduced the recovered E. coli population by 5 logs under the test conditions. The most effective sanitizer, peroxyacetic acid, achieved a 5-log reduction when used at 2.1 to 14 times its recommended concentration, depending on the length of the wash time. The chlorine-phosphate buffer solution reduced the population by 5 logs when used at 3 to 15 times its recommended concentration, depending on wash time. At no concentration or wash time tested did chlorine dioxide achieve the 5-log reduction.

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.

Production of PEGylated GCSF from Non-classical Inclusion Bodies Expressed in Escherichia coli

2021 ◽  
Author(s):  
Nguyen Thi My Trinh ◽  
Tran Linh Thuoc ◽  
Dang Thi Phuong Thao
Keyword(s):  
Escherichia Coli ◽  
Inclusion Bodies ◽  
Gel Filtration ◽  
Anion Exchange Chromatography ◽  
Insoluble Fraction ◽  
Exchange Chromatography ◽  
Native Page ◽  
E Coli ◽  
Sds Page ◽  
Stimulating Factor

Background: The recombinant human granulocyte colony stimulating factor con-jugated with polyethylene glycol (PEGylated GCSF) has currently been used as an efficient drug for the treatment of neutropenia caused by chemotherapy due to its long circulating half-life. Previous studies showed that Granulocyte Colony Stimula-ting Factor (GCSF) could be expressed as non-classical Inclusion Bodies (ncIBs), which contained likely correctly folded GCSF inside at low temperature. Therefore, in this study, a simple process was developed to produce PEGylated GCSF from ncIBs. Methods: BL21 (DE3)/pET-GCSF cells were cultured in the LiFlus GX 1.5 L bioreactor and the expression of GCSF was induced by adding 0.5 mM IPTG. After 24 hr of fermentation, cells were collected, resuspended, and disrupted. The insoluble fraction was obtained from cell lysates and dissolved in 0.1% N-lauroylsarcosine solution. The presence and structure of dissolved GCSF were verified using SDS-PAGE, Native-PAGE, and RP-HPLC analyses. The dissolved GCSF was directly used for the con-jugation with 5 kDa PEG. The PEGylated GCSF was purified using two purification steps, including anion exchange chromatography and gel filtration chromatography. Results: PEGylated GCSF was obtained with high purity (~97%) and was finally demonstrated as a form containing one GCSF molecule and one 5 kDa PEG molecule (monoPEG-GCSF). Conclusion: These results clearly indicate that the process developed in this study might be a potential and practical approach to produce PEGylated GCSF from ncIBs expressed in Escherichia coli (E. coli).

Predicting the Behavior of Escherichia coli Introduced as a Postprocessing Contaminant in Shrikhand, a Traditional Sweetened Lactic Fermented Milk Product

2001 ◽  
Vol 64 (4) ◽  
pp. 462-469 ◽  
Author(s):  
A. JAGANNATH ◽  
M. N. RAMESH ◽  
M. C. VARADARAJ
Keyword(s):  
Escherichia Coli ◽  
Response Surface ◽  
Storage Period ◽  
Fermented Milk ◽  
Behavioral Pattern ◽  
Milk Product ◽  
Initial Inoculum ◽  
E Coli ◽  
And Storage ◽  
Fermented Milk Product

The increasing popularity of traditional milk-based foods has placed emphasis on the need for microbial safety in food-chain establishments, as there are ample possibilities for foodborne pathogens to occur as postprocessing contaminants. The behavioral pattern of an enterotoxigenic strain of Escherichia coli D 21 introduced as a postprocessing contaminant in shrikhand, a traditional sweetened lactic fermented milk product, was studied with variables of initial inoculum (4.3, 5.3, and 6.3 log10 CFU/g), storage temperature (4, 10, and 16°C), and storage period (4, 9, and 14 days). During storage of shrikhand prepared individually with Lactobacillus delbruecki ssp. bulgaricus CFR 2028 and Lactococcus lactis ssp. cremoris B-634, there was a steady decrease in the viable count of E. coli that was proportional to the initial inoculum of E. coli introduced into shrikhand. The data were subjected to multivariate analysis, and equations were derived to predict the behavior of E. coli in shrikhand. The predicted values for the probable survival of E. coli showed good agreement with the experimental values with a majority of these predictions being fail-safe. The values of statistical indices showed that the model fits ranged between extremely good and satisfactory. Response surface plots were generated to describe the behavioral pattern of E. coli. The derived models and response surface plots enabled prediction of the survival of E. coli in shrikhand as a function of initial inoculum levels, storage temperatures, and storage periods of shrikhand. These predictions were valid within the limits of the experimental variables used to develop the model.

scholarly journals Effects of Essential Oils on Escherichia coli Inactivation in Cheese as Described by Meta-Regression Modelling

Foods ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 716
Author(s):  
Beatriz Nunes Silva ◽  
Vasco Cadavez ◽  
José António Teixeira ◽  
Ursula Gonzales-Barron
Keyword(s):  
Escherichia Coli ◽  
Essential Oils ◽  
Meta Analysis ◽  
Inhibitory Effects ◽  
Food Preservatives ◽  
E Coli ◽  
Log Reduction ◽  
Bactericidal Properties ◽  
Study Characteristics ◽  
Meta Regression

The growing intention to replace chemical food preservatives with plant-based antimicrobials that pose lower risks to human health has produced numerous studies describing the bactericidal properties of biopreservatives such as essential oils (EOs) in a variety of products, including cheese. This study aimed to perform a meta-analysis of literature data that could summarize the inactivation of Escherichia coli in cheese achieved by added EOs; and compare its inhibitory effectiveness by application method, antimicrobial concentration, and specific antimicrobials. After a systematic review, 362 observations on log reduction data and study characteristics were extracted from 16 studies. The meta-regression model suggested that pathogenic E. coli is more resistant to EO action than the non-pathogenic type (p < 0.0001), although in both cases the higher the EO dose, the greater the mean log reduction achieved (p < 0.0001). It also showed that, among the factual application methods, EOs’ incorporation in films render a steadier inactivation (p < 0.0001) than when directly applied to milk or smeared on cheese surface. Lemon balm, sage, shallot, and anise EOs showed the best inhibitory outcomes against the pathogen. The model also revealed the inadequacy of inoculating antimicrobials in cheese purposely grated for performing challenge studies, as this non-realistic application overestimates (p < 0.0001) the inhibitory effects of EOs.

Inhibition of Listeria monocytogenes and Escherichia coli O157:H7 on Beef by Application of Organic Acids†

1996 ◽  
Vol 59 (4) ◽  
pp. 370-373 ◽  
Author(s):  
R. K. PODOLAK ◽  
J. F. ZAYAS ◽  
C. L. KASTNER ◽  
D. Y. C. FUNG
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Fumaric Acid ◽  
Rank Order ◽  
Escherichia Coli O157 ◽  
Inoculum Level ◽  
Initial Inoculum ◽  
E Coli ◽  
Lean Beef ◽  
Lactic Acids

Lean beef surfaces were inoculated with Escherichia coli O157:H7 and Listeria monocytogenes and then sanitized with fumaric, acetic, or lactic acid alone and in combined solutions of those acids at 55°C for 5 s. The initial inoculum level was 8.62 log CFU/cm2 and 5.13 log CFU/cm2 for L. monocytogenes and E. coli O157:H7, respectively. Fumaric acid at a concentration of 1% was the most effective acid in reducing the populations of L. monocytogenes by up to 1 log unit and E. coli O157:H7 by up to 1.3 log units when compared with acetic or lactic acids. The rank order of acids tested against the growth of L. monocytogenes and E. coli O157:H7 was fumaric acid followed by lactic and acetic acids. Fumaric acid at concentrations of 1.0% and 1.5% was more effective than any of the combined solutions of acids.

scholarly journals Inactivation of Multi-Drug Resistant Non-Typhoidal Salmonella and Wild-Type Escherichia coli STEC Using Organic Acids: A Potential Alternative to the Food Industry

Pathogens ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 849
Author(s):  
Vinicius Silva Castro ◽  
Yhan da Silva Mutz ◽  
Denes Kaic Alves Rosario ◽  
Adelino Cunha-Neto ◽  
Eduardo Eustáquio de Souza Figueiredo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Organic Acids ◽  
Sodium Hypochlorite ◽  
Bacterial Species ◽  
Disk Diffusion ◽  
Clinical Strains ◽  
Linear Pattern ◽  
E Coli ◽  
Log Reduction

Salmonella and Escherichia coli are the main bacterial species involved in food outbreaks worldwide. Recent reports showed that chemical sanitizers commonly used to control these pathogens could induce antibiotic resistance. Therefore, this study aimed to describe the efficiency of chemical sanitizers and organic acids when inactivating wild and clinical strains of Salmonella and E. coli, targeting a 4-log reduction. To achieve this goal, three methods were applied. (i) Disk-diffusion challenge for organic acids. (ii) Determination of MIC for two acids (acetic and lactic), as well as two sanitizers (quaternary compound and sodium hypochlorite). (iii) The development of inactivation models from the previously defined concentrations. In disk-diffusion, the results indicated that wild strains have higher resistance potential when compared to clinical strains. Regarding the models, quaternary ammonium and lactic acid showed a linear pattern of inactivation, while sodium hypochlorite had a linear pattern with tail dispersion, and acetic acid has Weibull dispersion to E. coli. The concentration to 4-log reduction differed from Salmonella and E. coli in acetic acid and sodium hypochlorite. The use of organic acids is an alternative method for antimicrobial control. Our study indicates the levels of organic acids and sanitizers to be used in the inactivation of emerging foodborne pathogens.

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