Publicação
In vitro assessment of the ability of selected lactic acid bacteria to counteract foodborn pathogenic infections
| Resumo: | Listeria monocytogenes, Salmonella enterica and Escherichia coli O157:H7 are among the most important foodborne pathogens worldwide due to the considerable human rates of illness reported. The role of two selected Lactobacillus spp. strains (LABs), isolated from spontaneously fermenting olive brines, and two probiotic strains, L. casei Shirota and L. rhamnosus GG, in the attenuation of the virulence potential of these foodborne pathogenic bacteria were investigated in this work. The ability of LABs in adhering to the intestinal mucosa and counteracting bacterial infections in the gut was evaluated. Different in vitro tests of virulence, based on animal cells, were used. For the competitive exclusion assays, intestinal human cells (HT-29) were used with L. monocytogenes and Salmonella, in adhesion and invasion assays. With L. monocytogenes, plaque-forming assays (PFAs) were further performed. The cytotoxicity of E. coli O157:H7 Shiga toxins was evaluated by using a cytotoxicity assay based on lactate dehydrogenase release from Vero cells. In the present study, LAB strains showed strong inhibitory effects, with significative reduction (P<0.05) on the virulence potential of Salmonella and L. monocytogenes in adhesion and invasion of HT-29 cells. At the same time, it have been gathered initial evidences which indicating that cell free supernatants from LAB strains significantly reduced (P<0.05) the cytotoxicity produced by one E. coli O157:H7 strain. In conclusion, the results obtained suggest that the Lactobacillus strains tested in this study, L. plantarum and L. paraplantarum, are able to prevent infections by pathogens and can be considered as potential strains for probiotic use with interesting potential in preventing enteric infections in humans. |
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| Autores principais: | Dutra, Virna de Santiago, 1984- |
| Assunto: | Microbiologia alimentar Listeria monocytogenes Escherichia coli Salmonella enterica Teses de mestrado - 2013 |
| Ano: | 2013 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Listeria monocytogenes, Salmonella enterica and Escherichia coli O157:H7 are among the most important foodborne pathogens worldwide due to the considerable human rates of illness reported. The role of two selected Lactobacillus spp. strains (LABs), isolated from spontaneously fermenting olive brines, and two probiotic strains, L. casei Shirota and L. rhamnosus GG, in the attenuation of the virulence potential of these foodborne pathogenic bacteria were investigated in this work. The ability of LABs in adhering to the intestinal mucosa and counteracting bacterial infections in the gut was evaluated. Different in vitro tests of virulence, based on animal cells, were used. For the competitive exclusion assays, intestinal human cells (HT-29) were used with L. monocytogenes and Salmonella, in adhesion and invasion assays. With L. monocytogenes, plaque-forming assays (PFAs) were further performed. The cytotoxicity of E. coli O157:H7 Shiga toxins was evaluated by using a cytotoxicity assay based on lactate dehydrogenase release from Vero cells. In the present study, LAB strains showed strong inhibitory effects, with significative reduction (P<0.05) on the virulence potential of Salmonella and L. monocytogenes in adhesion and invasion of HT-29 cells. At the same time, it have been gathered initial evidences which indicating that cell free supernatants from LAB strains significantly reduced (P<0.05) the cytotoxicity produced by one E. coli O157:H7 strain. In conclusion, the results obtained suggest that the Lactobacillus strains tested in this study, L. plantarum and L. paraplantarum, are able to prevent infections by pathogens and can be considered as potential strains for probiotic use with interesting potential in preventing enteric infections in humans. |
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