scholarly journals Survival Enterohaemorrhagic E.coli O157in locally produce soft cheese in Baghdad city and studying the effect of some physical factors on its viability

2008 ◽  
Vol 32 (2) ◽  
pp. 108-119
Author(s):  
Najim Hadi Najim
Keyword(s):  
Statistical Analysis ◽  
Salt Concentration ◽  
Storage Temperature ◽  
Raw Milk ◽  
Physical Factors ◽  
High Concentration ◽  
Soft Cheese ◽  
Nonsignificant Effect

A total of 24 samples of three different kinds of locally produced softcheese manufactured from raw milk of Cows , Buffaloes and Ewes( 8 samples of each) were collected at weekly intervals from differentareas of Baghdad city in the period from the beginning of December2007 till the end of January 2008.The main objective of this study was to isolats , identify andenumerate Enterohaemorrhagic E.coli O157from locally produced softcheese , besides that , to study the effect of cheese storage temperature(4 C) and different salt concentration solutions on the viability andsurvival of E.coli O157 in stored cheese .Data demonstrate that 11 out 24 of samples 45.84% were found tohave Enterohaemorrhagic E.coli O157 and their average counts were1.6× 104 CFU/gm.The result of statistical analysis demonstrate that cheese samplesmanufactured from cows raw milk had significantly ( P> 0.05) higherE.coli O157 counts and isolation rates over both cheese samples thatwere manufactured from Ewes and buffaloes raw milk .the average count of Enterohaemorrhagic E.coli O157 in cheesemanufactured from cows milk were 3.8× 104 CFU/gm and the isolationpercentage was 75% while their average counts in cheese manufacturedfrom Ewes and buffaloes milk were 7.3 ×103 & 2.4 ×103 CFU/gmrespectively and the isolation percentages were 37.5 % & 12.5%respectively.Data revealed that all soft cheese samples that were found to haveEnterohaemorrhagic E.coli O157 and stored at refrigeration temperature(4 C) had non significant ( P<0.05) reduction in the average counts ofE.coli O157after 3 weeks of storage and this indicate that the refrigerationstorage temperature (4 C) had no significant effect on the viabilityand survival of E.col O157 .All soft cheese samples that were found tohave Enterohaemorrhagic E.coli O157 were stored in brinesolutions at different salt concentrations such as 2.5%, 5%,7% and10% for 24 hr,1 week, 2weeks & 3weeks . Data revealed that brinesolution at high concentration of salt such as 10% had nonsignificant effect on the viability and survival of E.coli O157after 3weeks of storage.

scholarly journals The combined effect of bacteriocin-producing Lactobacillus rhamnosus GG-ATCC and Lactoperoxidase system activation on microbiological quality of raw milk with special emphasis against E.coli O157:H7 in milk

2017 ◽  
Vol 40 (2) ◽  
pp. 66-72
Author(s):  
Najim Hadi Najim
Keyword(s):  
Storage Temperature ◽  
Lactobacillus Rhamnosus ◽  
Microbiological Quality ◽  
Raw Milk ◽  
Latex Agglutination ◽  
Bacterial Cells ◽  
Lactobacillus Rhamnosus Gg ◽  
Time Period ◽  
Soft Cheese ◽  
Chromogenic Agar

     Isolates of Enterohaemorrhagic E.coli O157:H7 were isolated from 51 and 41 of locally produced bovine and ovine soft cheese samples. Their identification were confirmed based on the biochemical reactions and both the morphological cultural and serological properties. Presumptive E.coli O157:H7 isolates obtained by using the conventional selective plating on the chromogenic agar were tested further for the presence of both O157 and H7 antigenes using the latex agglutination test antisera. The current microbiological studies revealed that 31 (33.70 %) out of 92 bovine and ovine soft cheese samples were positive for E.coli O157:H7. The highest non significant (P>0.05) prevalence level of E.coli O157:H7 was found in the ewe᾿s soft cheese samples (36.59 %) followed by cow᾿s soft cheese samples (31.37 %). Agar well diffusion bioassay method was used for measuring the antibacterial activity of the crude bacteriocin that was produced by Lactobacillus rhamnosus GG-ATCC against Escherichia coli and the closely related sensitive strains such as L.acidophilus LA-K and L.acidophilus ROO52. The crude bacteriocin that was produced by the L.rhamnosus GG-TACC exhibited significantly (P<0.05) the highest antibacterial potency (100 %) against both the closely related strains of lactobacilli and the stressed E.coli O157:H7 by the activation of the LPS. The activation of the natural LPS of inoculated pasteurized milk had significantly (P<0.05) influenced the inactivation degree of the crude bacteriocin against E.coli O157:H7. There was a significant (P<0.05) reduction in the viable counts of stressed E.coli O157:H7 after each exposure time period (6, 24 and 48 hrs.) to the crude bacteriocin at room storage temperature. An overall conclusion on the basis of the current results pointed  out  that complete  elimination of viable bacterial cells was not achieved  neither  in  the stabilized milk (Activation of LPS) nor after  subjecting  the stabilized  milk to the action of the crude bacteriocin produced by L.rhamnosus GG-ATCC at room storage temperature.

scholarly journals Bioassay activity of crude bacteriocin produced by Lactobacillus acidophilus isolate against cold stressed E.coli O157:H7

2012 ◽  
Vol 36 (0E) ◽  
pp. 268-273
Author(s):  
Najim Hadi Najim
Keyword(s):  
Lactobacillus Acidophilus ◽  
Inhibitory Concentration ◽  
Storage Temperature ◽  
Raw Milk ◽  
Latex Agglutination ◽  
Pathogenic Organism ◽  
Selective Enrichment ◽  
Cultural Isolation ◽  
Soft Cheese ◽  
Refrigeration Storage

The laboratory studies of the cultural isolation revealed that two isolates of Lactobacillus acidophilus were isolated from five soft cheese samples that were manufactured locally according to the farmers production procedure .Colonies of E.coli O157:H7 were isolated from raw milk samples by a conventional direct plating on selective enrichment CT-SMAC agar and tested serologically for the presence of O157 and H7 antigens using the commercial available latex agglutination kits .The results revealed that E.coli O157:H7 was resist to the crude bacteriocin that was extracted from L .acidophilus isolate NO.1 due to the nature of their cell wall, while when the outer membrane of E.coli O157:H7 was injured by cooling at 4°C for 6 hours , the permeation of bacteriocin to the cytoplasmic membrane was facilitated and caused inactivation and death of such pathogenic organism .The results revealed that no growth of E.coli O157:H7 with no visible turbidity in the nutrient broth with bacteriocin that diluted to 1\2 ,1\4 ,1\8 were observed .Bacteriocin that diluted to 1\8 had been recognized as the minimum inhibitory concentration of the bacteriocin.Both the dilution factor of bacteriocin and time exposure to bacteriocin at refrigeration storage temperature of milk had a significant (P˂0.05) influence on its antimicrobial potency against the viability of stressed E.coli O157:H7 from minutes 30 to 120 .The viability of E.coli O157:H7 subjected to bacteriocin that diluted 10 times(1:10) in both raw and sterile milk was efficiently eliminated after 90 minutes and 60 minutes of exposure at refrigeration temperature respectively.

Effect of High Salt Concentration on Ion Clustering and Transport in Polymer Solid Electrolytes: a Molecular Dynamics Study of PEO-LiTFSI

2018 ◽  
Author(s):  
Nicola Molinari ◽  
Jonathan P. Mailoa ◽  
Boris Kozinsky
Keyword(s):  
Polymer Electrolyte ◽  
Salt Concentration ◽  
Rational Design ◽  
Material System ◽  
Ion Dynamics ◽  
High Concentration ◽  
Anion Clusters ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

<div> <div> <div> <p>The model and analysis methods developed in this work are generally applicable to any polymer electrolyte/cation-anion combination, but we focus on the currently most prominent polymer electrolyte material system: poly(ethylene) oxide/Li- bis(trifluoromethane) sulfonamide (PEO + LiTFSI). The obtained results are surprising and challenge the conventional understanding of ionic transport in polymer electrolytes: the investigation of a technologically relevant salt concentration range (1 - 4 M) revealed the central role of the anion in coordinating and hindering Li ion movement. Our results provide insights into correlated ion dynamics, at the same time enabling rational design of better PEO-based electrolytes. In particular, we report the following novel observations. 1. Strong binding of the Li cation with the polymer competes with significant correlation of the cation with the salt anion. 2. The appearance of cation-anion clusters, especially at high concentration. 3. The asymmetry in the composition (and therefore charge) of such clusters; specifically, we find the tendency for clusters to have a higher number of anions than cations.</p> </div> </div> </div>

Effect of High Salt Concentration on Ion Clustering and Transport in Polymer Solid Electrolytes: a Molecular Dynamics Study of PEO-LiTFSI

2018 ◽  
Author(s):  
Nicola Molinari ◽  
Jonathan P. Mailoa ◽  
Boris Kozinsky
Keyword(s):  
Polymer Electrolyte ◽  
Salt Concentration ◽  
Rational Design ◽  
Material System ◽  
Ion Dynamics ◽  
High Concentration ◽  
Anion Clusters ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

<div> <div> <div> <p>The model and analysis methods developed in this work are generally applicable to any polymer electrolyte/cation-anion combination, but we focus on the currently most prominent polymer electrolyte material system: poly(ethylene) oxide/Li- bis(trifluoromethane) sulfonamide (PEO + LiTFSI). The obtained results are surprising and challenge the conventional understanding of ionic transport in polymer electrolytes: the investigation of a technologically relevant salt concentration range (1 - 4 M) revealed the central role of the anion in coordinating and hindering Li ion movement. Our results provide insights into correlated ion dynamics, at the same time enabling rational design of better PEO-based electrolytes. In particular, we report the following novel observations. 1. Strong binding of the Li cation with the polymer competes with significant correlation of the cation with the salt anion. 2. The appearance of cation-anion clusters, especially at high concentration. 3. The asymmetry in the composition (and therefore charge) of such clusters; specifically, we find the tendency for clusters to have a higher number of anions than cations.</p> </div> </div> </div>

Prevalence of Listeria species in raw milk, ice cream and yogurt and effect of selected natural herbal extract on its survival

2020 ◽  
Vol 21 (3) ◽  
pp. 99-106
Author(s):  
Mona Yousef ◽  
Hazem Ramadan ◽  
Maha Al-Ashmawy
Keyword(s):  
Plant Extract ◽  
Reduction Rate ◽  
Ice Cream ◽  
Raw Milk ◽  
Inhibitory Effect ◽  
Food Preservation ◽  
Herbal Extract ◽  
Listeria Species ◽  
Soft Cheese ◽  
High Reduction

Objective: This study aimed to detect the prevalence of Listeria species in raw milk, ice cream and yogurt, and to evaluate the effect of extract of clove, thyme and pomegranate peel on such organism. Design: Descriptive study. Procedures: One hundred and fifty samples of milk, ice cream and yogurt were examined for isolation, identification and molecular identification of Listeria spp. Extraction of natural plant extract as clove, thyme and pomegranate peels and detection of their inhibitory effect on Listeria spp. Results: The prevalence of Listeria spp. in milk was 36% where 14% as L. monocytogenes, 6% L. innocua and 16% and other Listeria spp. was 16%. In yogurt, Listeria spp. was 6% as L. innocua was 2% and other Listeria spp. was 4%, while no L. monocytogenes was detected. In ice cream, Listeria spp. was 8% where L. monocytogenes was 2% and other Listeria spp. was 6% while no L. innocua was detected. The concentration of plant extract was 2.5% which showed high reduction rate on L. innocua and L. monocytogenes during shelf life of soft cheese. Conclusion and clinical relevance: Listeria is widely isolated from milk than from ice cream and yogurt. Plant extracts play role in food preservation and consider as a natural antimicrobial agent where most effective one was clove extract.

scholarly journals Influence of soft cheese technology on the growth and enterotoxin production of Staphylococcus aureus

2009 ◽  
Vol 27 (No. 2) ◽  
pp. 127-133 ◽  
Author(s):  
L. Necidová ◽  
Z. Šťástková ◽  
M. Pospíšilová ◽  
B. Janštová ◽  
J. Strejček ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Technological Process ◽  
Raw Milk ◽  
Toxin Production ◽  
Milk Products ◽  
Model Experiments ◽  
Soft Cheese ◽  
Strict Compliance ◽  
Technological Processing ◽  
And Storage

The aim of this study was to monitor <I>S. aureus</I> growth and toxin production in soft cheese during the technological processing. In model experiments, raw milk was inoculated separately with five <I>S. aureus</I> strains isolated from milk and milk products. All the strains were producers of staphylococcal enterotoxins (SEs) of types A, B, or C. SEs were detected by the enzyme-linked fluorescence assay (ELFA) performed in the MiniVIDAS device. This study has shown that the amount of SEs varied with the tested strains and stages of the technological process. SEs were detected in soft cheese made from pasteurised milk inoculated with 2.9 × 10<sup>5</sup> CFU/g of <I>S. aureus</I>. The prevention of <I>S. aureus</I> contamination and multiplication during the cheese making process is a prerequisite for the production of safe soft cheese. The most important enterotoxin dose build-up factor can be overcome by strict compliance with the cooling requirements during the manufacture, distribution and storage of the product.

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