Tesi sul tema "Escherichia-Shigella"
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Blanchard, Geneviève. "Versatilité nutritionnelle de l'espèce génomique "Escherichia Coli-Shigella"". Paris 5, 1990. http://www.theses.fr/1990PA05P055.
Albuquerque, José Antonio Tavares de. "Análise comparativa da transcrição de genes envolvidos na invasão e escape de \'Escherichia coli\' enteroinvasora e \'Shigella flexneri\' em macrófagos J774". Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-17102006-094359/.
Enteroinvasive Escherichia coli (EIEC) serotypes described so far share antigenic, biochemical, genetic and pathogenetic properties with Shigella sp. However, in order for an infectious process to occur, an inoculum of 102 Shigella cells is needed in contrast to as much as 106 EIEC cells. The characteristic ability of S. flexneri and EIEC to enter epithelial cells, multiply intracellularly and spread from cell to cell is uniquely encoded by their 220-kb virulence plasmid. Previous studies realized in our laboratory showed that the genes ipaA, ipaB, ipaC and ipaD do not possess molecular alterations in the nucleotides sequences that can explain the difference in the pathogenicity between EIEC and Shigella spp. In the present work, the transcription levels of the bacterial genes involved in the invasion and escape from host cells were evaluated. Through reverse transcription-polymerase chain reaction (RT-PCR) analysis, differences in the transcription levels for the majority selected virulence genes could be observed when bacteria were in contact with the macrophages. However, without the contact with those cells, the transcription levels of the genes were the same between both bacteria species, with the exception of ipaD. When the bacteria is in contact with macrophages, the transcription of ipaD is the same in both species whereas in the absence of macrophages, the transcription level is lower in EIEC than Shigella, when compared in the same period of time. Those results provided the selection of the genes for the real time PCR analysis. In general, the EIEC transcription levels genes are lower than Shigella. More still, the icsB showed a distinct kinetic of transcription from the others genes in the same operon. All results suggest that the lower pathogenicity due to EIEC can partially have to the differences of the virulence genes transcription. Still more, the genes-encoded by operon icsB-ipaCB seem to be regulated of a distinct form. Therefore, transcription of the ipaD in EIEC probably depends on distinct signaling way of S. flexneri. New studies shows to be necessary for the better understanding of the pathogenic mechanism of EIEC.
Pehrson, Moysés Estevão de Souza Freitas. "Avaliação da atividade antimicrobiana de substâncias sintetizadas por cepas de Lactobacillus sp. que apresentam propriedades probióticas". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/97/97132/tde-14092016-163724/.
Infectious diseases caused by gram-negative pathogens are important sources of losses in livestock, especially bovine, ovine and poultry. In many cases, subclinical administration of broad-spectrum antibiotics is chosen as an approach for the prevention of these infections, consequently decreasing these losses. However, this practice presents an important risk to human health, as well as it contributes to the selection of bacterial strains which are resistant to antibiotics usually employed in clinical practice. Therefore, special attention has been given to finding alternative procedures to decrease those losses while eliminating that risk. One of these alternatives consists of using microorganism species which present probiotic properties such as synthesis of inhibitory compounds that act on intestinal pathogen species. This alternative virtually eliminates the risk of developing resistance to broad-spectrum antibiotics, as well as avoids the presence of antibiotic residues in animal products. The term \"probiotic\" is currently used to define microorganism species which promote several benefits to the host, once they are administered frequently and in adequate amounts. In the last few years, several works have been carried out using four Lactobacillus strains (L.acidophilus ATCC 4356, L.casei ATCC 7469, L. fermentum ATCC 9338 and L. plantarum ATCC 8014), and the results have been satisfactory regarding to their probiotic characteristics. Therefore, the aim of this study was to evaluate the ability of these strains to produce inhibitory compounds which are active on gram-negative intestinal pathogen species, specifically Escherichia coli 0112, Escherichia coli 0124, Escherichia coli 0127, Shigella sonnei ATCC 25931, Shigella dysenteriae ATCC 13313 and Salmonella enteritidis ATCC 13076. So, antimicrobial activity of the cell-free supernatant of each strain was evaluated. Additionally, presumptive characterization of these compounds was undertaken by submitting the supernatants to different treatments (catalase, proteolytic enzymes, thermic treatments, pH neutralizing). The strategy consisted of evaluating the growth, estimated by turbidimetry, of the mentioned pathogenic strains in the presence of the original supernatants, as well as in the presence of treated supernatants. Aborbance values were statistically analyzed by means of ANOVA and Tukey\'s test. The results showed that the original supernatants of L. acidophilus ATCC 4356 L. casei ATCC 7469 and L. plantarum ATCC 8014 were capable of inhibiting five of six strains of enteric pathogens at levels varying from 23% to 53%. S. dysenteriae ATCC 13313 was not inhibited by the Lactobacillus strains evaluated. It was also demonstrated that only the original supernatant of L. fermentum ATCC 9338 showed inhibitory activity upon this strain varing from 15% to 32%, and between 36% and 65% regarding to the other strains. Growth evaluation of the pathogenic strains in the presence of the treated and original supernatants revealed that the inhibition effect observed occurred due to the presence of organic acids, which lowered the pH of the supernatants. It was also demonstrated the absence of hydrogen peroxide, peptidic and thermolabile compounds in the supernatants.
Santos, Hadassa Cristhina de Azevedo Soares dos. "Caracterização molecular e fenotípica da disseminação de diferentes sorotipos de Escherichia coli enteroinvasora em células epiteliais intestinais da linhagem Caco-2". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-16042013-101737/.
Enteroinvasive Escherichia coli (EIEC) and Shigella spp cause bacillary dysentery in humans by invading and multiplying within epithelial cells of the colonic mucosa. Although EIEC and Shigella spp share many genetic and biochemical similarities, the illness caused by EIEC is less severe. The effector proteins IcsA and IcsB are important in the physiopathology of the disease triggered by EIEC and Shigella spp. IcsA is required for intracellular actin-based motility, and the role of IcsB is to camouflage IcsA from the autophagic host defense system. Previous studies showed that EIEC O124:H- showed a significantly less efficient cell-to-cell Caco-2 dissemination when compared with S. flexneri. Due to these results the following question arose: Are molecular and phenotypic differences restricted to serotype O124:H- or is it common to EIEC pathotype? Thus, this study evaluated the phenotypic and molecular characteristics of eleven different serotypes of EIEC and compares them to samples of S. flexneri. All EIEC serotypes presented lower cell-to-cell Caco-2 dissemination compared to Shigella M90T, and the differences between this two species expanded to the icsA and icsB gene sequences, in which it was possible to observe a polymorphism of the genes. The smallest spread presented by EIEC E. coli pathotype could be associated with the connection process and/or recruitment of N-WASP, as well as to other important host proteins.
Izabel, Hugo de Alencar. "Estudo da proteína OppA em amostras diarreiogênicas de Escherichia coli, Shigella e Salmonella". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-28012008-134840/.
The oligopeptide uptake system (Opp), involved with the uptake of peptides formed by 3 or more amino acid residues, represent important nutrient uptake mechanism. The Opp operon is usually represented by 5 structural genes, including OppD and OppF encoding proteins involved generation of energy , OppB and OppC, encoding membrane proteins delimiting a pore and OppA encoding the protein responsible both for specificity and affinity of the transport system toward different peptide substrates. In this study, we demonstrated that the OppA proteins expressed by different E. coli strains,4 Shigella species (99%) and different serovars of Salmonella enterica (85%) were quite conserved but the occurrence of inter-species polymorphism was demonstrated. The OppA gene was detected in 58 diarrheogenic E. coli, Shigella and Salmonella strains. Using a recombinant OppA protein produced in E. coli, specific polyclonal sera were generated and successfully applied in the immunological detection of the proteins expressed by the tested strains. Thus, we conclude that the OppA protein is present and conserved among species and strains of the three test Enterobacteriaceae genera.
Moreno, Ana Carolina Ramos. "Diferença de patogenicidade entre Escherichia coli enteroinvasora e Shigella flexneri em modelo experimental de infecção intestinal". Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-25112016-142513/.
In this study, we clarify topics of pathogenicity from EIEC that support its lower level of virulence when it is compared to S. flexneri, and we have shown the importance of dendritic cells (DC) in this process. We studied the conduct of EIEC and S. flexneri when they were in contact with Caco-2 cells and we analyzed the kinetics of the genes expression that was involved in the spread and invasion of the bacteria. In general, all genes were expressed less in EIEC, as demonstrated by the phenotype of the bacterial spread, where EIEC was less efficient than Shigella. We also analyzed the modulation of the inflammatory response by the murine intestinal dendritic cells by the production of cytokine, expression of co-stimulators molecules and antigens presentation, after the interaction of the cells with the bacteria. The results showed that EIEC induces a response that protects the host while Shigella manipulate the host intestinal innate and adaptive immune system and it probably over-stimulates the adaptive immune system which could let the disease worse. The integrated actions of Caco-2 cells, dendritic cells and bacterial stimulus, were studied in a co-culture cell. We observed that EIEC and its secreted proteins induce the migration of the DCs to the apical compartment of the co-culture; nothing was observed related to Shigella. We also evaluated the concentrations of the inflammatory cytokines at the infective micro environment that was formed. The cytokine TNF-α, as CCL20 and MCP-1 were more prominent after been stimulated with EIEC, a fact that could partially explain the migration of DCs to the apical side of the co-culture after the stimulus with EIEC and its secreted proteins. Our experimental evidence shows that the disease triggered by the EIEC is more restricted at a definite infection place, which means that it is not capable of disseminating beyond a certain point to extend the tissue\'s injury and let it worsen, as Shigella do. This phenomenon can be associated with the lower level of expression of its virulence factors and to the immune response induced in the infection site, what could finally lead to the eradication of the disease.
Li, Yong. "Simultaneous detection of Escherichia coli O157:H7, Salmonella and Shigella by polymerase chain reaction-based methods /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcitt?p3144436.
Silva, Gracie Luiza da. "Estudo da ação inibitória da quitosana sobre os enteropatógenos: Salmonella enterica, Shigella sonnei e Escherichia coli EPEC". Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/82/82131/tde-10052006-095954/.
The aim of this study was to evaluate the inhibitory action of chitosan solutions derived from shrimp (Fluka commercial type, MW 600.000 g/mol, acetylation degree of 76%) and squid (MW '10 POT.7' g/mol, acetylation degree of 83%) through determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against enteropathogens: Salmonella enterica, Shigella sonnei and Escherichia coli EPEC. Those solutions were set to pH 5,0 and a 0,5% concentration in a 1% acetic acid solution. The best antimicrobial activity of chitosan occurs in pH less than or equal to 5,0 and it shows precipitation in pH greater than 6,5. Those features were decisive to choose the pH used in the MIC test. In order to confirm that the growth inhibition of enteropathogens occurred by the action of chitosan and not for the acid pH of the environments, growth evaluation tests of enteropathogens were accomplished in MacConkey agar, pH 5,0 (excellent for chitosan) and pH 7,4 (excellent for culture of used bacteria). The inoculum of each bacterium was prepared comparing with the 0,5 tube of McFarland (positive control) and the evaluation was repeated using the inoculum diluted in a salt solution 1:1000 to count the number of colonies, which did not show significant differences. The reaction evaluation of precipitation of chitosan was done in Müeller Hinton broth with pH ranging 4,0 - 8,0 for both solutions of chitosan (v/v), which were incubated at 37°C and read for 72 hours. The MIC evaluation for both solutions of chitosan for the enteropathogens was done by serial dilution and the inocula were compared to the 0,5 tube of McFarland, adding 10 'mü'L of bacterial suspension to each tube, which were incubated at 37°C for 24 hours. The MIC was distinguished by the absence of visible turbidity. Each tube that did not show visible turbidity was spread on MacConkey agar plates in pH 7,4, and incubated at 37°C for 24 hours to find the MBC, which was determined by the smallest concentration able to cause total death to the enteropathogen population. In both cases, the solutions of chitosan presented a high antimicrobial activity against the enteropathogens Salmonella enterica and Escherichia coli EPEC. However, the higher antimicrobial activity was observed in the enteropathogen Shigella sonnei
Pilonieta, Maria Carolina. "Transcriptional Regulation of Virulence Genes in Enterotoxigenic Escherichia coli and Shigella flexneri by Members of the AraC/XylS Family". Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/111.
Silva, Renée de Nazaré Oliveira da. "Caracterização molecular dos genes ospC1, ospG e ospF em diferentes sorotipos de Escherichia coli enteroinvasora". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-26042013-093005/.
Enteroinvasive E. coli (EIEC) is one of the etiological agents of bacillary dysentery, it is characterized by the destruction of the colonic epithelium caused by the inflammatory response induced upon invasion of the mucosa by bacteria. Strains of EIEC are biochemical, genetic and pathogenic similar to Shigella spp. The pathogenecity of EIEC and Shigella depend on the presence of the plasmid pInv, which contains the genes necessary for bacterial colonization in the intestinal mucosa. Recently, it was demonstrated that the plasmid genes ospC1, ospG and ospF of S. flexneri are involved in inhibition of the inflammatory response in intestinal epithelial cells, an important factor in the initiation of bacterial colonization and production of disease. As EIEC has showed less severe disease, we evaluated the transcription of these plasmid genes and inflammatory response modulated by this microorganism in the intestinal epithelial cell Caco-2. The Caco-2 cells were infected in different times with 11 serotypes of EIEC and S. flexneri M90T strain. The data about sequences of amino acids, invasiveness and survival of bacteria, bacterial genes expression, and chemokine IL-8 were obtained by CFU, RT-PCR, and ELISA, respectively. The statistical significance was evaluated by two-way ANOVA. All EIEC serotypes studied showed 100% similarity with S.flexneri to OspC1 and OSPF, however, were different in the homology of OspG. Compared the amino acid sequences of the 11 serotypes observed 100% similarity between them to OspG, suggesting the involvement of them in modulating of the immune response induced by these microorganisms. There were no differences in the invasion the enterocytes among EIEC serotypes. However, some significant differences were observed in the transcription of those genes and production of IL-8. The EIEC serotypes O29:H- and O167:H- showed a low transcription of genes ospC1 and ospF, and a significant increase in production of IL-8 when compared with other serotypes. Furthermore, it was shown that the high transcription of ospF and ospC1 by some EIEC serotypes are related to low induction of IL-8. These data suggested that the proteins OspC1 and OspF play a role in the inflammatory response. However, we did not observed association between ospG transcription to the production of IL-8. These results lead us to believe that the effector proteins OspF and OspC1 are involved in inhibition of the inflammatory response in intestinal epithelial cells favoring the EIEC invasion.
Wang, Luxin. "Simultaneous quantitation of Escherichia coli O157:H7, salmonella and shigella in ground beef by multiplex real-time PCR and immunomagnetic separation". Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4598.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (Feb. 23, 2007). Includes bibliographical references.
Mirza, Zainulabedeen Reda. "Control of Shigella sonnei and adhesive invasive Escherichia coli infections with a natural product which inhibits the bacterial oxidoreductase DsbA". Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28637.
Ferreira, Lucas Gonçalves. "Caracterização da resposta inflamatória induzida por Escherichia coli enteroinvasora (EIEC) e Shigella flexneri em células epiteliais intestinais da linhagem Caco-2". Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-20092017-173828/.
Escherichia coli enteroinvasive (EIEC) and Shigella sp cause bacillary dysentery which is characterized by the invasion and destruction of the human colon mucosa. Samples of EIEC have characteristics biochemical, genetic and pathogenic similar to those of Shigella species, however the disease caused by EIEC is more lenient. The cells of the intestinal epithelium actively participate in the mucosal immunity by expression and production of several inflammatory mediators such as cytokines, chemokines, adhesion molecules and nitric oxide. For better understanding of the EIEC pathogenesis, we studied the inflammatory response modulated by this microorganism in intestinal epithelial cells Caco-2, comparing it with Shigella flexneri. Caco-2 cells were infected with EIEC or S. flexneri during different intervals of time and analyzed the invasiveness and spread bacteria capacity (CFU, PLAQUE ASSAY), induction of cell death (FACS), analysis of genes involved in the recognition of bacterial and inflammatory response (RT-PCR, RPA), production of pro-inflammatory cytokines and chemokines (ELISA) and nitric oxide (NO) (GRIESS). In this work was possible to observe that: (i) the ability to spread and (ii) the induction of cell death in Caco-2 cells was significantly higher in S. flexneri infection than EIEC, (iii) there are differences regarding the relative expression of genes of Caco-2 cells involved in the recognition of two bacterial strains. It was highlighted the essential role of intracellular receptors in recognition of bacterial by Caco-2 cells, and the expression of mRNA of the intracellular receptor Nod 1 was higher for EIEC when compared with S. flexneri, (iv) there are significant differences in the kinetics of NO production by Caco-2 infected cells, EIEC induced a early NO production when compared with S. flexneri. These data indicate that the intestinal epithelial cells recognize and respond in a different way to these bacterial species and induce an inflammatory response more efficient in control of the infection induced by EIEC.
Pinchaud, Katleen. "Impact d'un apport alimentaire en acide arachidonique sur le microbiote intestinal et l'axe intestin-cerveau. Conséquences pour une prévention de la maladie d'Alzheimer par les probiotiques". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0190.
Alzheimer's disease (AD) is a neurodegenerative disease associated with aging, consisting of a major public health problem worldwide. There is currently no effective treatment or established preventions for this disease, highlighting the importance of the design of preventive strategies in the fight against this disease. Western diets are particularly rich in ω-6 fatty acids, especially arachidonic acid (ARA), which are converted into many inflammation mediators in the organism. Previous laboratory results have shown that dietary intake of ARA sensitizes mice to the neurotoxicity of Aβ peptide oligomers, the main agent of AD. In this thesis work, we studied the impact of this dietary intake of ARA on the fecal microbiota and the microbiota-gut-brain axis. For 9 to 12 weeks, three groups of 15 mice have consumed one of these 3 diets : a conventional murine diet (“Sdt-ARA” of 5% lipids), a moderately high-fat diet of 15% lipids including 31.9% of linoleic acid ("HL-ARA"), and a diet of 15% lipids including 25.3% linoleic acid and 6.6% ARA ("HL+ARA").Analysis of the fecal microbiota revealed that the "HL-ARA" diet promotes proliferation of the Bifidobacterium pseudolongum strain, which has been show to possess anti-inflammatory activities. Furthermore, the supply of ARA suppresses this proliferation by favouring Escherichia-Shigella multiplication (with potentiating effects on inflammation). A 3-to-11-fold increase in mRNA levels of the pro-inflammatory cytokines IL-1β and TNFα has been observed in the colon of mice fed with the "HL+ARA" diet. Enrichment of ARA led to an increase of the expression of other mediators of colon inflammation such as CD40, adiponectin, and ICAM-1, as well as the claudin 1 and occludin markers which are components of cellular tight junctions. Therefore, these changes in expression suggest that the integrity of the intestinal barrier has been compromised. Moreover, dietary intake of ARA led to a 10 fold increase in TNFα mRNA levels in mesenteric adipose tissue, while the impact on the liver was found to be much more moderate. At the cerebral level, a 9 weeks food intake of ARA led to a 1.5-1.8-fold increase in the protein level of GFAP in the hippocampus and the cortex, while no changes of the microglial marker Iba1 has not been reported. We also found decreased levels of IL-6 and TNFα mRNA in the global brain tissue.These results indicate that dietary intake of ARA induces low-grade systemic inflammation which may promote the expansion of an Alzheimer's-like process in the brain if an inducing signal occurs. As such, we also evaluated the impact of an innovative oral administration model of D-galactose, which has been described as an aging accelerator compound , leading to impairment of cognitive capacities, and the appearance of amyloid plaques in the mouse brains through elevated oxidative stress. We also studied the survival in the digestive tract of two strains of Streptococcus thermophilus with anti-inflammatory activity in vitro as reported by previous laboratory work, and of a strain of Lactobacillus plantarum capable of metabolizing ω-6 polyunsaturated fatty acids in conjugated fatty acids. This thesis work aims to assess the ability of these probiotic strains to fight against low-grade inflammation induced by dietary intake of ARAs and oxidative stress induced by D-galactose. New work is underway in the laboratory to investigate in more details all the biological processes at work in the different models and to determine the impact of probiotics on a combined administration of D-galactose and an ARA-enriched diet
Freyburger, Ludovic. "Etude de la réponse immunitaire cellulaire systémique et humorale muqueuse suite à la vaccination par la sous-unité B de la toxine de Shigella Dysenteriae comme vecteur d'antigène". Paris 5, 2007. http://www.theses.fr/2007PA05T028.
The Shiga toxin subunit B (STxB) is a vaccinal vector targeting dendritic cells. CD4+ and CD8+ T cells responses as well as antibody production were observed after vaccination of mice with chimeric proteins composed of STxB coupled with different antigens. STxB doesn't favour maturation of dendritic cells, thus we assessed the STxB efficiency as vector in combination with different adjuvants. STxB coupled with different antigens and mixed with aGalCer, a glycolipide activating NKT cells, resulted in an increase CD8+ T cells frequency and it also allowed the dramaticaly reduction of antigen doses. This vaccine also permitted to break tolerance to self-antigens and to protect against the development of viral infection. In addition, we have showed that the route of immunization had an influence on the type of immune response (mucosal humoral response jind cellular^ systemic response) observed after the use of STxB
Ma, Li doctor of cellular and molecular biology. "Cellular iron metabolism and reductase systems in Escherichia coli and Shigella flexneri". Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6160.
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Desai, Stuti. "Aromatic Beta-Glucoside Utilization In Shigella Sonnei : Comparison With The Escherichia Coli Paradigm". Thesis, 2009. https://etd.iisc.ac.in/handle/2005/946.
Desai, Stuti. "Aromatic Beta-Glucoside Utilization In Shigella Sonnei : Comparison With The Escherichia Coli Paradigm". Thesis, 2009. http://hdl.handle.net/2005/946.
"Estudo da ação inibitória da quitosana sobre os enteropatógenos: Salmonella enterica, Shigella sonnei e Escherichia coli EPEC". Tese, Biblioteca Digital de Teses e Dissertações da USP, 2006. http://www.teses.usp.br/teses/disponiveis/82/82131/tde-10052006-095954/.
Walters, Laura Lesley. "StcE of Escherichia coli O157:H7 : characterization of substrate recognition and identification of a homolog in Shigella boydii /". 2007. http://www.library.wisc.edu/databases/connect/dissertations.html.
"Análise comparativa da transcrição de genes envolvidos na invasão e escape de \'Escherichia coli\' enteroinvasora e \'Shigella flexneri\' em macrófagos J774". Tese, Biblioteca Digital de Teses e Dissertações da USP, 2006. http://www.teses.usp.br/teses/disponiveis/9/9136/tde-17102006-094359/.
Shu-Chen, Hsu, e 許淑真. "Comparison of the partial sequence of mdh genes and designing of PCR primers for the detection of Escherichia coli and Shigella spp". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/34217888630246861540.
國立中興大學
食品科學系
87
The presence of Escherichia coli has traditionally been considered an indicator microorganism of fecal contamination in food and in environmental water, and few of them are pathogenic to cause serious disease and food poisoning. So E. coli is therefore a widely used measure of sanitary quality. The common method for detecting and quantifying E. coli requires a minimum of 5 to 7 days to obtain results after initiation of sample analysis. Incorporated MUG to culture broth (i.e MUG-LST) were developed, but it could yield false-positive and false-negative results. The time and accuracy limitation suggested the need for more rapid methods for detecting E. coli. The first purpose of the study is to design PCR primers for the specific detection of the mdh gene of E. coli strains. Positively amplified DNA bands generated for all tested E. coli and Shigella spp. cells collected in our laboratory, and non-E. coli strains would not produce the specific PCR product. The detection sensitivity of Emdh1/ Emdh2 primers (25 pmole each) was 100 CFU per assay. In detection of E. coli cells in milk samples, tap water, underground water and lake water, the detection sensitivity would be 100 CFU if a pre-enrichment step using MacConkey broth was performed prior to the PCR. Owing the DNA relationship of E. coli and Shigella are homologous (about 70%~ 100%) in molecular level was reported. So the second work were sequencing Emdh1/ Emdh2 PCR products and structural gene in mdh gene of Shigella spp. for understanding the similarity. The results showed that the homology of E. coli and Shigella spp. was up to 98%. On the third part of the work, we have tried to develop PCR methods for the differentiation of viable and non-viable cells. By short term culture of the target cells followed by suitable dilution and PCR assay, non-viable cells could be differentiated from the viable cells since non-viable cells could not grow and its DNA would not give any PCR product due to dilution out of the cells. The detection sensitivity of viable cells were 100 CFU per assay, but the detection sensitivity of non-viable cells treated with autoclave sterilized, boiled-killing, Presterization and 70% EtOH were 102 CFU per assay. If a 8 hours pre-enrichment step was performed prior to PCR, could not generate target PCR products even the original non-viable cells number were 105 cells. Finally, mdh gene specific PCR primers Emdh1/ Emdh2 and MDH31/ MDH2 were combined into a multiplex PCR system and used for the simultaneous detection of E. coli and Salmonella typhimurium. On detection of E. coli and S. typhimurium cells in whole milk and drinking water, if a 8 hours pre-enrichment step was performed prior to PCR, the detection sensitivity for target cells in samples would be reach to 100/ 100 CFU per assay. When two target strains were different numbers mixed to the food samples, however, it was found that the ratio of original cell numbers should be within 102 so that the target strains with lower cell numbers could be detectable.
Joseph, Asha Mary. "Exploring the Evolution of Cellobiose Utilization in Shigella Sonnei And the Conservation of ChbG Orthologs in Eukaryotes". Thesis, 2016. http://etd.iisc.ac.in/handle/2005/2710.
Joseph, Asha Mary. "Exploring the Evolution of Cellobiose Utilization in Shigella Sonnei And the Conservation of ChbG Orthologs in Eukaryotes". Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2710.
Chigayo, K. "A study of the chemical components of extracts from kirkia wilmsii and an investigation into their properties". Diss., 2015. http://hdl.handle.net/11602/272.
Ledwaba, Solanka Ellen. "Prevalence of selected bacterial and viral entero-pathogens in children less than 5 years of age in Limpopo Province, South Africa". Diss., 2016. http://hdl.handle.net/11602/779.
Phuti, Moukangoe Getrude. "Synthesis, characterization and antimicrobial activity of cobalt and cobalt sulphide nanoparticles against selected microbes that are found in wastewater". Thesis, 2018. http://hdl.handle.net/10352/447.
Water shortages, water pollution and climate changes are highly interrelated global issues. These have raised immense concerns about serious adverse effects on the quality, treatment and re-use of wastewater. A major role of water is for vitality of life on earth. Water is recognized as source of evolution from origin to degree of civilization, since it is an essential resource its treatment becomes a necessity for day to day for life. Nanoparticles and their application in treatment of wastewater is becoming a major area of research. It is mainly applicable to the removal of major contaminants like microorganisms. This study was carried out with an objective to investigate the antibacterial and antifungal potentials of nanoparticles. Cobalt and cobalt complexes of urea and thiourea were synthesized and characterized using UV-Vs, PL, FTIR, TEM, SEM, XRD and TGA techniques. The Co particles are in a mixture of rod, agglomerates with irregular shape around 50 – 100 nm in diameter. The Co/Thiourea particles appear to be around 10 – 30nm in size. The Co complexed with urea images showed spherical to hexagonal shape with 50 nm size in diameter. The antimicrobial activity was determined using Minimum Inhibitory and bactericidal concentration and the well diffusion method. The antibacterial and antifungal activities of ratios (1:1, 1:2, 1:3, 2:1 μg/mL) of doped cobalt nanoparticles were tested against a panel of five Gramnegative bacteria - (Escherichia coli, Pseudomonas aeruginosa, Shigella enterica, Salmonella typhi and Salmonella sonnei) human pathogenic bacteria; and two fungal strains - Aspergillus niger and Candida albicans. Zones of inhibition as a consequence of nanoparticles were compared with that of different standards like Neomycin for antibacterial activity and Amphotericin B for antifungal activity. The results showed a remarkable inhibition of the bacterial growth against the tested organisms. The most striking feature of this study is that Cobalt, Urea and Thiourea nanoparticles have antifungal activity comparable or more effective (as in case of Thiourea on A. niger) than Amphotericin B and nearly promising antibacterial activity although not comparable to Neomycin.