The different roles of hcp1 and hcp2 of the type VI secretion system in Escherichia coli strain CE129
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Type VI secretion system (T6SS) is a secretory system found in Gram-negative bacteria. One of the main structures for T6SS is Hcp (hemolysin co-regulation protein) pipeline. To investigate the role of Hcp major sub-unit genes hcp1 and hcp2 , we deleted hcp1 and hcp2 genes for constructing the in-frame gene deletion mutants. The properties of biofilm formation and the adhesion to chicken embryo fibroblasts cells (DF1 cells) were reduced in the hcp2 mutant. The knockout of hcp1 and hcp2 genes reduced the ability of the avian pathogenic Escherichia coli (APEC) strain CE129 to infect developing chicken embryos. The expression of quorum sensing (QS)-associated genes luxS, lsrR, and pfs were down-regulated in the hcp1 mutant, and the expression of type 1 fimbriae gene fimA and the adhesion-related genes fimC and papC were decreased in the hcp2 mutant, as well as the expression of anti-serum survival factor genes ompA and iss were inhibited in both hcp1 and hcp2 mutants. These results described above from this study help to further elaborate the role of HCP in APEC.Keywords:
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Bacteriostatic experiment of twelve species of Chinese medicines and its compounds against escherichia coli K88 and hemoclatic escherichia coli had been made.The result showed that nine species of Chinese medicines had shown bacteriostasis against escherichia coli K88 and eleven species against hemoclastic escherichia coli. All compounds had shown bacteriostasis against escherichia coli Kgg and hemoclastic escherichia coli.The bacteriostatic effect of compuond 5 was superior to enrofloxacin's(1‰) against escherichia coli K88 (P0.05), and the bacteriostatic effect of compound 5 was superior to enrofloxacin's (1‰) against hemoclastic escherichia coli (P0.01 ).There was synergism between coptis root and enrofloxacin.
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Background: The level of pollution in Indonesia is still very high, consist of water pollution, air pollution and soil pollution. Mercury is one of the heavy metals that pollutes the waters of the sea, while Escherichia coli is exposed to mercury will try to defend itself by doing mercury detoxification so that it can live in an environment that contains mercury. Escherichia coli that tries to defend itself from mercury exposure in the environment will experience a change in its genes into mercury resistant Escherichia coli. In plasmids or transposons, it might also stimulate the formation of resistance genes for some antibiotics, include producing the ESBL enzyme, so that it can convert non ESBL Escherichia coli into ESBL Escherichia coli. Objective: This study aims to prove that the repeated exposure of mercury will change non ESBL-mercury sensitive Escherichia coli into ESBL- mercury resistant Escherichia coli. Method: This was an experimental study with 27 non-ESBL Escherichia coli isolates as identified from Phoenix. Non-ESBL Escherichia coli clinical isolates were tested by giving exposure to HgCl2 with concentrations of 0.02 ppm, 0.10 ppm, 0.20 ppm for 1-14 days until mercury resistant Escherichia coli was formed, and then ESBL screening was tested by giving Cefotaxime exposure to them. Results: On the first day of mercury exposure, there were 9 isolates of 0.02 ppm HgCl2 resistant Escherichia coli, 9 isolates of 0.10 ppm HgCl2 resistant Escherichia coli, 9 isolates of 0.20 ppm HgCl2 resistant Escherichia coli. Furthermore, this Escherichia coli isolate was exposed to Cefotaxim as ESBL screening. The final results of post-exposure HgCl2 0.02 ppm was obtained 3 (33.3%) isolates were still sensitive to Cefotaxime and 6 (66.7%) isolates that were resistant to Cefotaxime. The final results of post-exposure HgCl2 0.10 ppm was obtained all 9 (100%) isolates that were resistant to Cefotaxime. The final results of post-exposure HgCl2 0.20 ppm obtained 2 (22.2%) isolates were still sensitive to Cefotaxime and 7 (77.8%) isolate were resistant to Cefotaxime. Conclusion: Escherichia coli in urine had the phenotive change into mercury resistant Escherichia coli. Mercury exposure of 0.02 ppm, 0.10 ppm, 0.20 ppm for 1 day in vitro on isolates of non ESBL-mercury resistant Escherichia coli caused changes in 22 isolates of Escherichia coli in urine
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Актуальність. В Україні з кожним роком відзначається збільшення кількості жінок, вагітність яких перебігає на тлі хронічних інфекційних захворювань. Escherichia coli є частим збудником бактеріальних інфекцій у жінок. Метою дослідження було виявлення морфологічних особливостей нирок плодів і новонароджених від матерів з експериментальним абдомінальним підгострим інфекційно-запальним процесом, викликаним Escherichia coli. Матеріали та методи. Авторами проведено експеримент на щурах лінії WAG, в ході якого сформовано дві групи: група I — 7 плодів та 11 новонароджених від 3 здорових самок; група II — 10 плодів і 13 новонароджених від 4 самок, яким моделювали абдомінальний інфекційно-запальний процес, викликаний Escherichia coli. Матеріалом дослідження послужили нирки плодів та новонароджених. Використовували гістологічні, гістохімічні, морфометричні та статистичні методи досліджень. Результати. Абдомінальний підгострий інфекційно-запальний процес в організмі матері, викликаний Escherichia coli, призводить до структурних змін у паренхіматозному та стромальному компонентах нирок, які наростали від плода до новонародженого. Гломерулярний апарат нирок характеризується нерівномірним розташуванням у кірковому шарі, затримкою розвитку, зміною форми, гемодинамічними змінами, розширенням сечового простору, відсутністю судинних клубочків, зменшенням кількості і компактності розташування капілярних петель в деяких молодих і зрілих ниркових тільцях; тубулярний апарат — затримкою розвитку, зміною форми та вогнищевим потовщенням базальних мембран окремих канальців, вогнищевими дистрофічними, некротичними та десквамативними змінами епітеліальної вистилки; стромальний компонент — склеротичними змінами, гемодинамічними порушеннями, більш вираженими в мозковому шарі, клітинною інфільтрацією, яка характеризується наявністю клітин фібробластичного ряду та імунних клітин. Висновки. Гістологічні та морфометричні зміни, що розвинулися в нирках плодів і новонароджених, зумовлені наявністю у матері експериментального підгострого інфекційно-запального процесу в черевній порожнині, викликаного Escherichia coli, призведуть в майбутньому до зниження функціональних можливостей нирок як гомеостатичного органу і розвитку різної нефрологічної патології у таких дітей.
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To investigate the mechanism of drug resistance of biofilm escherichia coli.The model of escherichia coli biofilm was established with the flat-board method. And the biofilm was confirmed by scanning electron microscopy. The beta-lactamase activities were quantitated, in escherichia coli, biofilm escherichia coli, biofilm escherichia coli induced by impenem or cefoxitin.The beta-lactamase activity of biofilm escherichia coli was 2.16 times as much as that of escherichia coli planctonically, and the beta-lactamase activities of biofilm escherichia coli induceded by impenem or cefoxitin were 1.30 and 1.05 times as much as those of biofilm escherichia coli, respectively.The drug resistance to antibiotics of biofilm escherichia coli was related to the production of beta-lactamase.
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ve To explore the regularity of changes of density of three strains of Escherichia coli in un-dernourished water at different 4 levels of temperature. Methods The simulated water samples respectively prepared with standard strains of ATCC 25922, 8099 and wild strain of Escherichia coli seperated from human faeces were in-cubated in thermostat water bath at temperatures of 5℃ , 15℃, 25℃ and 35℃ respectively. The densities of Es-cherichia coli in water samples were determined by filter membrane fluorometry quantitatively. Results No prolif-eration of Escherichia coli was found in undernourished water samples. The densities of Escherichia coli variated with the incubation durations at different temperatures according to negative exponential function:y=ae-bt. The orders of speed of decrease of Escherichia coli density in water samples were ATCC 25922 wild strain of Escherichia coli 8099 at the same temperature, and at the different temperatures: 35℃ 25℃ 15℃ . Conclusion The changes of density of different strains of Escherichia coli in the undernourished water samples closely associated with the strain ' characteristics, environment temperatures and preserving time, showed significantly differences.
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Objective To investigate the mechanism of drug resistance of biofilm escherichia coli .Methods The model of escherichia coli biofilm was established with the flat board method And the biofilm was confirmed by scanning electron microscopy The β lactamase activities were quantitated in escherichia coli, biofilm escherichia coli , biofilm escherichia coli induced by impenem or cefoxitin. Results The β lactamase activity of biofilm escherichia coli was 2 16 times as much as that of escherichia coli planctonically, and the β lactamase activities of biofilm escherichia coli induceded by impenem or cefoxitin were 1 30 and 1 05 times as much as those of biofilm escherichia coli ,respectively.Conclusion The drug resistance to antibiotics of biofilm escherichia coli was related to the production of β lactamase.
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[Objective]The damage in the cell membrane of bacteria could be reflected on the leakiness of the material in bacteria and the absorption of dye in bacteria.Compared with pasteurization(63 °C,30 min),the damaging effect of pressurized CO2 on the cell membrane of Escherichia coli was studied.The aim of the study was to analyze the relationship between the death of Escherichia coli and the damage of cell membrane.[Methods]The change of cell membrane permeability and the leakiness of protein and nucleic acid in Escherichia coli were detected.The change of Escherichia coli morphology was observed by TEM.[Results]The results indicated that pressurized CO2 treatment induced the change of cell membrane permeability of Escherichia coli.Pressurized CO2 treatment induced the leakiness of protein in Escherichia coli,but the time of leakiness was lagged behind the time of 99% Escherichia coli death,so it was not the reason for death,it was only the secondary phenomenon of death.The death of Escherichia coli could be related to the leakiness of nucleic acid induced by the pressurized CO2 treatment.The death of Escherichia coli could be related to the ultrastructure change of Escherichia coli induced by the pressurized CO2 treatment.[Conclusion]There was direct relationship between the damaging effect of pressurized CO2 on cell membrane of Escherichia coli and the death of Escherichia coli.
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Host, vector, and culture conditions (including cultivation media) are considered among the three main elements contributing to a successful production of recombinant proteins. Accordingly, one of the most common hosts to produce recombinant therapeutic proteins is Escherichia coli.A comprehensive literature review was performed to identify important factors affecting production of recombinant proteins in Escherichia coli.Escherichia coli is taken into account as the easiest, quickest, and cheapest host with a fully known genome. Thus, numerous modifications have been carried out on Escherichia coli to optimize it as a good candidate for protein expression and; as a result, several engineered strains of Escherichia coli have been designed. In general; host strain, vector, and cultivation parameters are recognized as crucial ones determining success of recombinant protein expression in Escherichia coli. In this review, the role of host, vector, and culture conditions along with current pros and cons of different types of these factors leading to success of recombinant protein expression in Escherichia coli were discussed.Successful protein expression in Escherichia coli necessitates a broad knowledge about physicochemical properties of recombinant proteins, selection among common strains of Escherichia coli and vectors, as well as factors related to media including time, temperature, and inducer.
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A total of nine Escherichia coli O157:H7 isolates were originally isolated from imported Indian beef purchased from local retail markets. These nine Escherichia coli O157:H7 isolates were confirmed as Escherichia coli O157:H7 by their positive growth characteristics on Rainbow agar O157 and PCR assay for the detection of the presence of the H7 (fliC) gene unique to Escherichia coli O157:H7. Published specific primers FLICH (625 bp) of the fliC gene encoding the H7 antigen were utilized in the specific PCR assay. Three of the Escherichia coli O157:H7 isolates were selected for the amplification of their H7 (fliC) gene. The amplicon of the PCR assay were successfully cloned into pGEM-T vector and sequenced. The sequence of the Escherichia coli O157:H7 that was obtained from sequencing was analyzed. This sequence was identified using Basic Local Alignment Search Tools (Blast) program. Based on the sequence obtained, primer pairs were designed to detect the Escherichia coli O157:H7, but only Sk7 and Sk8 were found to be specific for detection of locally isolated Escherichia coli O157:H7. Sk7 and Sk8 produced an amplicon size of 520 bp and 603 bp respectively against all tested locally isolated Escherichia coli O157:H7. Both new primers were specific against Escherichia coli O157:H7, as they did not produce any amplicons from the 32 isolats representing 20 different bacterial species. DNA hybridization analysis of 10 other bacterial species, including E. coli, Salmonella and other isolates showed that the probe (SkP) reacted only with Escherichia coli O157:H7 isolates.
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A strain of Escherichia coli has been isolated which possesses minimum postirradiation degradation properties. Starting with E. coli ${\rm B}_{{\rm s}-1}$, mutational selection procedures were used to select for cells which do not degrade their DNA. Our strain (PHH1) does not degrade its DNA when exposed to 20 krad or less. It has a high survival capacity, even greater than E. coli B/r. This strain has an OER of about 3.0. The insensitivity of this cell to radiation-induced degradation suggests that it is a prime candidate for the study of relative sensitivities of the molecular apparatus of cells to ionizing radiation.
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