Showing 12 results for E. Coli
Volume 3, Issue 9 (7-2006)
Abstract
Aerobic mesophilic counts (AMC), were obtained by swabbing 25 cm2 areas at seven site (neck, brisket, leg, flank, rib set, forehand, hind quarter) on beef carcasses, after each Slaughter process (skinning, evisceration, splitting, trimming and primary washing, final washing). Reduction in counts at individual sites were observed after trimming and primary washing (about 0.2 log cfu.cm-2 ) and final washing (about 0.2 log cfu.cm-2 ) similarly. Increases in counts at most outside sites were observed after skinning, (about 2.5 - 3.5 log cfu.cm-2) and after evisceration, at brisket (about 1 log cfu.cm-2) and forehand (about 0.5 log cfu.cm-2) respectively. The incidence of Salmonella and E. coli on beef carcasses were also obtained by swabbing the outside surfaces of 12 carcasses after each stage. A large number of increases in positive samples for E.coli and Salmonella was observed after skinning and after evisceration (16.6% and 9.2% respectively). After final washing Salmonella and E. coli were detected on 11.9% and 7.1% of samples. The impact of beef slaughter processes on carcass microbiology and their potential use as critical control points (CCPs) during beef production are discussed.
Volume 5, Issue 1 (1-2019)
Abstract
Background: With increasing infectious diseases as well as antimicrobial resistance in pathogens to existing drugs, researchers are now seeking for new drug candidates to be used as alternatives or complementary therapies. Maca is commonly used in traditional medication as herbal medicine.
Materials & Methods: In this research, the antibacterial and antifungal activities of maca powder and ethanolic extract were evaluated against Staphylococcus aureus ATCC25923, Pseudomonas aeruginosa ATCC27853, Escherichia coli ATCC25922, Enterococcus faecalis ATCC29212, and Candida albicans ATCC10231 using Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and disc diffusion methods.
Results: The obtained results showed that there was no significant difference between the MIC and MBC of maca powder and extract against the reference and clinical strains. Also, no strain showed zone of inhibition at 30, 40, 50, and 60 µl of reference concentration.
Conclusion: According to the results obtained in this study, maca powder and extract had a poor inhibitory effect on bacterial and fungal growth.
Volume 6, Issue 1 (3-2017)
Abstract
Cucumber mosaic virus (CMV) is one of widely-spread viruses of plants with the broadest host range encompassing over 1200 species. One major limiting factor for detection of the virus is unavailability of the virus-specific antibodies especially in developing countries. Recombinant DNA technology facilitates antibody preparation without requiring special equipment. In this study, coat protein (CP) gene cDNA of CMV was subcloned from pTZ57CMVCP into pET21a expression vector and transformed into Escherichia coli strain Rosetta. Expression of CMV CP was examined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and its identity was confirmed by western blotting, dot blot immunobinding assay (DIBA) and enzyme- linked immunosorbent assay (ELISA) using anti- CMV antibody. The expressed protein was purified using T7•Tag affinity purification kit and used as antigen for raising polyclonal antibodies in two mice. The purified anti-CMV CP IgG and the conjugated IgG performed favourably in terms of specificity and sensitivity to detect both expressed CP (antigen) and CMV isolates in infected cucurbit plants using plate trapped antigen (PTA)- ELISA, double-antibody sandwich (DAS)-ELISA and western blotting. The prepared antibodies can be applied in serological and sero-molecular tests in studies on the virus and in screening of plants for the infection. This is the first report of preparation of antibodies against CP of an indigenous isolate of CMV.
Volume 7, Issue 4 (11-2021)
Abstract
Backgrounds: Neonatal sepsis is a clinical syndrome in neonates, which is an uncommon but significant cause of morbidity and mortality in infants. The aim of this study was to evaluate the incidence of sepsis caused by Escherichia coli and its antibiotic resistance pattern as well as to assess the potential risk factors in neonates and maternal characteristics in Shiraz.
Material & Method: This retrospective study was performed on infants with sepsis in the first three days of life during February 2019 to March 2021. Patients' information was obtained using their hospital records and a questionnaire. All statistical analyses were conducted using SPSS software Ver. 18.0. A p-value <.05 was considered as statistically significant
Findings: During this study, a total of 250 positive blood cultures were reported for infants less than 3 days old. Of these, 21(8.4%) E. coli strains were isolated from 14 preterm and 7 term neonates. In all patients, the most effective antibiotic was meropenem, and the highest resistance was observed to cefoxitin.
Conclusion: Base on the present study results, E. coli is the most prevalent Gram-negative bacterium isolated in Shiraz. Premature birth and very low weight are the most important risk factors for developing early-onset sepsis.
Volume 7, Issue 27 (12-2010)
Abstract
Adding food preservatives is one of the methods for increasing shelf-life and decreasing total bacterial count. Using experimental model as liquid substance and solid substrate is necessary for survey of antibacterial and preservative effect of essential oils. In This study, effect of different concentrations of Cinnamomum zeylanicum Blume. essential oil (0.00، 0.005، 0.015& 0.03%), temperatures (8 º C & 25 º C) and storage time (up to 21 days) was evaluated in a food model system (Hamburger). The results showed that effect of different concentrations of essential oil on growth rate of E. coli O157:H7 was statistically significant (p<0.01).Thus the effect of storage time on growth rate was statistically significant (p<0.01). In addition, decreasing the storage temperature (from 25º C to 8ºC) affected on decrease of the growth rate of the microorganism (p<0.01). Therefore The 0.03 % of cinnamon concentration in 8 º C has increasing effect in shelf-life in hamburger. Therefore using this essential oil as natural preservatives in low temperature in meat products is suggested.
S. Abbaszadeh , N. Bakhtiari , Z. Amin-Bayat,
Volume 10, Issue 1 (3-2019)
Abstract
Aims: There are several cell disruption methods for intracellular protein extraction. The aim of this study was to select the best approach for recombinant teriparatide fusion protein extraction from E. coli and achieve the best purification conditions.
Materials & Methods: In this experimental research, bacterial cells were disrupted by different methods such as sonication in different cycles, grinding with liquid nitrogen in two different cell culture volumes, and homogenization at two different pressures. The supernatant and pellet samples were run on sodium dodecyl sulphate gel. All the cell lysates were cultured on LB agar medium and stained with Gram staining method. The Ni2+ affinity chromatography of recombinant teriparatide fusion protein was done under denaturing and non-denaturing conditions, using pH and imidazole concentration gradient, respectively. All samples were taken on sodium dodecyl sulphate-polyacrylamide gel and the amount of purified protein was calculated by Micro-Bradford assay.
Findings: In the 20 and 25 cycles, a large part of the fusion protein led to protein solubilization. In the method of grinding with liquid nitrogen, proteins were more likely to enter the sediment part. The cell disruption was complete in a chemical method. The cell disruption under 50bar homogenization was more than that of 15bar. In chemical degradation and sonication, a large amount of fusion protein led to protein solubilization. In non-denaturing conditions, no recombinant fusion protein was removed from the column with the isolation buffer, but in the denaturing conditions, a large amount of proteins was purified.
Conclusion: The combined method of chemical degradation and sonication leads to approximately 97.7% of protein solubilization, and the purification in denaturing condition has also the suitable result in contrast to non-denaturing condition.
Z. Hajihassan, S.m. Sadat, P. Gholami Tilko ,
Volume 10, Issue 1 (3-2019)
Abstract
Aims: Nerve growth factor (β-NGF) is an important therapeutic agent for the treatment of neurodegenerative diseases such as Alzheimer’s disease; so, recombinant production of it in industrial scale is of high importance. The aim of this study is to optimize the effective factors in achieving the highest rate of β-NGF protein production in the bioreactor.
Materials & Methods: As E. coli is a suitable host for industrial production of recombinant proteins, E. coli DE3 strain was used for production of recombinant β-NGF. Also, fermentation was performed in a 5-L bioreactor and % dissolved oxygen (%DO) and post-induction temperature values were optimized by response surface methodology (RSM). At first, the effects of these two variables on the level of total protein were studied. So, in every experiment, bacterial proteins were isolated and total protein concentration was determined by Bradford assay.
Findings: The results indicated that %DO and post-induction temperature of 30% and 28.5ºC were the best values for increased production of total protein; in these circumstances, total protein concentration was 9.6±0.61 mg/ml. Finally, the effects of these variables on recombinant β-NGF production were surveyed by dot blot analysis, indicating the maximum β-NGF expression level on the optimized condition.
Conclusion: In conclusion, %DO and post-induction temperature not only affect cell growth of recombinant E. coli, but also have a direct impact on recombinant protein expression and production, such as β-NGF.
Saeedeh Ghiasvand, Akbar Vaseghi, Firoozeh Alavian,
Volume 11, Issue 1 (3-2020)
Abstract
Escherichia coli is a
Gram-negative bacterium, the second most common bacteria in the intestine and the main indicator of urban water pollution, is the most common cause of urinary tract infection and also is one of the main factors in food poisoning and diarrhea. Drug resistance of this bacterium to antibiotics is a global challenge. Horizontal gene transfer (HGT) is the movement of genetic material between
unicellular and other gene transfer pathways which is an important factor in the evolution of many organisms,
antibiotic resistance in bacteria, gene function. Antibiotic resistance in E. coli can be transferred to another species of bacteria through HGT mechanisms. Today, Bioinformatics methods have been used to understand of gene transfer from HGT mechanism. In this study, we used bioinformatics tools such as PredictBias, ACLAME, Mobil Genetic Elements (MGEs) PAI-ID, and Alien_Hunter in order to genes analysis that related from
antibiotic resistance in E. coli. Bioinformatics and MIC assays result show that from 26 to 30 genes have been identified in all safthwers. Most of genes that identified show over 50 percent of GC content.
put P gene with 178,
blaCMY with 62,
BlaTEM with 43, and
aac-6 with 66 homology in the PredictBias website identified. Also in the ACLAME website
, mob (A-C) and rep (A-C) gene family are highest number of horizontal gene transfer from infection bacteria strain. Those cluster genes are the highest resistant of laboratory tests which carries resistant genes such as blaSHV and blaCHV on the blaCMY plasmid.
Orod Ghavimi, Zahra Hajihassan, Fatemeh Armaghan,
Volume 12, Issue 2 (1-2022)
Abstract
Activin A, a member of the transforming growth factor-β (TGF-β) superfamily, plays a central role in numerous physiological processes such as cell differentiation, tissue repair, angiogenesis, differentiation of stem cells, cell adhesion and apoptosis. Because of its various clinical usages, recombinant production of it is beneficial. Since E. coli is one of the most popular hosts for recombinant protein production, in this study, cytoplasmic expression in this strain was used to produce high levels of Activin A. So, the cDNA of the Activin A mature region was amplified and then cloned in pET28a(+) vector. The resulting vector was transformed to BL21(DE3), BL21(DE3)plysS, and BL21(DE3)Rosetta-gami strains. After induction the promoter by using IPTG, Activin A production was confirmed by SDS-PAGE and Western blotting assays. The results showed that the expression of Activin A in the cytoplasm of all three strains was an efficient approach to obtain high levels of recombinant protein, but BL21(DE3) strain produced more protein. At the next step in order to achieve soluble form of Activin A, co-expression of cytoplasmic chaperones TF, GroEL/ES, and DnaK with pET28a (+) vector was used. The SDS-PAGE and Western blotting results showed that co-expression of Activin A with cytoplasmic plasmid pGro7 containing GroEL and GroES chaperones, in BL21(DE3) strain is an efficient approach for producing of soluble Activin A.
Mohadeseh Farnaghizad, Yasaman Issazadeh, Sarvenaz Falsafi, Ava Behrouzi,
Volume 14, Issue 3 (2-2024)
Abstract
Pseudomonas aeruginosa is one of the most important causes of infection in medicine, which in recent years is known as an antibiotic resistant bacterium. One of the antibiotic resistance strategies of this bacterium is algD and PpyR genes expression for biofilm formation.
In recent years, it has been shown that using microorganisms, such as probiotics, is a method of pathogen bacterium harnessing, hence, in this study, for preventing biofilm formation of P. aeruginosa, E.coli Nissle 1917(EcN) probiotic bacterium is used, as a new treatment choice.
Due to direct relationship between antibiotic resistance and biofilm formation, strains with the
highest antibiotic resistance was chosen by antibiogram test. Then, in order to determine the inhibition rate of EcN bacterium in the formation of biofilm caused by P. aeruginosa bacterium, a biofilm formation test was performed.
At the end, to evaluate algD and PpyR genes expression, which were key parts of biofilm formation, in the presence of probiotic EcN bacterium, Real- time PCR method was used.
Based on the results of the biofilm formation test, EcN bacterium showed a high inhibitory effect on the formation of biofilm caused by P. aeruginosa bacterium.
.Also, in assessment of algD and PpyR genes expression in presence of EcN probiotic, a significant reduction in PpyR gene expression has been seen, in comparison with control group. The results of this study showed that EcN probiotic can act as a suitable new treatment option, to reduce P. aeruginosa biofilm formation.
Volume 17, Issue 103 (8-2020)
Abstract
Various methods have been developed to detect the presence of contamination with Coliforms and E. coli in foods. The pour plate technique using VRBA medium is confirmed as a standard method in Iran. The biggest disadvantage of this method is the need to spend a lot of time, high volume of laboratory operations, multiple stages and ultimately long time to achieve the results. Today, due to the mass production of various foodstuffs, the need for faster methods with high sensitivity to control the quality of food is necessary for the responsible oversight centers. The use of chromogenic medias is also one of the fastest diagnostic methods that have been developed. According to this matter, a comparative study was considered from the results of application of three chromogenic media and reference method in food quality control. Totally 100 samples of foodstuffs were evaluated for contamination to Coliform and E.coli using standard method and three chromogenic medias. Based on the obtained results, 86, 79, 85 and 80 samples were contaminated to Coliform using the standard method, Coliform Agar ES, ChromAgar ECC and Rapid E.coli 2/Agar respectively. Also, using four mentioned methods, contamination to E.coli was reported at 66, 80, 84 and 80, respectively. Cochrane test showed that there was no significant difference between the four methods in Coliform diagnosis (p>0.05). However, four methods did not have the same function in the detection of E. coli so that the chromogenic methods showed significant difference with the standard method (p< 0/001). But there was no significant difference between these chromogenic methods in detecting E.coli (p>0.05). According to the statistical analysis of present study, three chromogenic medias can be used instead of the standard method for the detection of Coliform, but the use of these chromogenic medias is not recommended for the identification of E.coli.
Volume 23, Issue 1 (1-2020)
Abstract
Amis: In recent years, carbon nanotubes have attracted the attention of many researchers because of their unique properties. In the present study, carbon nanotubes were coated using PEI. Then, their ability to gene delivery to E. coli cells was examined.
Materials & Methods: Nanotube- PEI nanoparticles were synthesized by the reaction between amine groups of PEI and carboxyl groups of nanotubes. In order to prepare the appropriate DNA vector for delivering to E. coli cells, the Gus A gene was transferred from pBI121 to PUC18 vector (pUC-Gus). Nanotube-PEI/DNA complexes were prepared by combining different mass ratios of nanotube-PEI (0.5, 1, and 2 w/w%) with the fixed amount of DNA. To the transformation of E. coli, the appropriate amount of nanotube-PEI/DNA complexes was added to E. coli cells under stirring at 37°C for 7h. The transformation efficiency of E. coli was determined by colony counting on LB agar supplemented with Ampicillin. Moreover, Gus staining assay was used to confirm the function of the plasmid. Determination of cytotoxicity of nanotube-PEI was performed using MTT assay at 6, 24, and 72 hours intervals at different concentrations of nanotube-PEI (10, 100, and 500μg/ml).
Findings: The nanotube-PEI was synthesized successfully. Nanotube- PEI nanoparticles have a great ability to protect DNA from enzymatic digestion. The percentage of E. coli cells viability was decreased by increasing both the concentration of nanotube-PEI nanoparticles and also the duration of incubation. The results of the agarose gel electrophoresis of plasmid extracted from E. coli and digested using EcoRI enzyme showed that the pUC-Gus plasmid has been successfully transfected by nanotube-PEI nanoparticles to E. coli bacterial cells.
Conclusion: Cationic carbon nanotubes have a high ability to gene transfer to E. coli.
