Browsing by Author "Leite, Daniela"
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- Campylobacter spp. as a foodborne pathogen: a reviewPublication . Silva, Joana; Leite, Daniela; Fernandes, Mariana; Mena, Cristina; Gibbs, Paul Anthony; Teixeira, PaulaCampylobacter is well recognized as the leading cause of bacterial foodborne diarrheal disease worldwide. Symptoms can range from mild to serious infections of the children and the elderly and permanent neurological symptoms. The organism is a cytochrome oxidase positive, microaerophilic, curved Gram-negative rod exhibiting corkscrew motility and is carried in the intestine of many wild and domestic animals, particularly avian species including poultry. Intestinal colonization results in healthy animals as carriers. In contrast with the most recent published reviews that cover specific aspects of Campylobacter/campylobacteriosis, this broad review aims at elucidating and discussing the (i) genus Campylobacter, growth and survival characteristics; (ii) detection, isolation and confirmation of Campylobacter; (iii) campylobacteriosis and presence of virulence factors; and (iv) colonization of poultry and control strategies.
- Evaluation of a bacteriocin-producing strain of pediococcus acidilactici as a biopreservative for "alheira", a fermented meat sausagePublication . Albano, Helena; Pinho, Catarina; Leite, Daniela; Barbosa, Joana; Silva, Joana; Carneiro, Luísa; Magalhães, Rui; Hogg, Tim; Teixeira, PaulaThis study was conducted to evaluate the ability of Pediococcus acidilactici HA-6111-2, a PA-1 bacteriocinproducing lactic acid bacterium (LAB), isolated from ‘‘Alheira” to inhibit a cocktail of Listeria innocua strains during production and shelf-life of these products. The bacteriocinogenic culture reduced the Listeria population below the detection limit (1.5log CFU/g) and had no effect on the growth of the natural LAB flora or on the pH. Pathogenic organisms were not detected in any sample. The presence of some virulence factors and antibiotic resistances of the strain to be used as a bioprotective culture were investigated. P. acidilactici HA-6111-2 did not produce any of the biogenic amines tested; no formation of biofilms was observed; more L(+)lactic acid was produced than its isomer D(-); no gelatinase, DNase or lipase activity was recorded; no structural genes for the haemolysin, enterococcal surface protein, hydrolytic compounds, aggregation protein and cell-wall adhesins were detected, no significant antibiotic resistances were found. P. acidilactici HA-6111-2 appears to have potential as a bioprotective culture during ‘‘Alheira” fermentation. Moreover, a trained panel considered the protected product to be sensorially acceptable.
- Evaluation of the effect of freeze-drying on potential probiotic properties of different lactic acid bacteriaPublication . Leite, Daniela; Ramalheira, Rosário; Silva, Joana; Gibbs, P.; Teixeira, PaulaThe potential probiotic properties of different strains of lactic acid bacteria previously isolated from commercial yo- gurts and from "alheira”, a traditional Portuguese fermented dry sausage, have been evaluated during this study. Sus- ceptibility to different antibiotics and the survival under the simulated gastrointestinal conditions, were examined before and after freeze-drying in the presence and in the absence of skim milk 11 % (wiv). Lactobacillus plantarum and Pedic- coccus aciclilactici were the most resistant to the adverse conditions of the gastrointestinal tract and to the antibiotics tested. All the isolates were demonstrated to be vancomycin resistant. ln general, antibiotic resistance decreased after freezedrying. Resistance to gastrointestinal conditions decreased afterfreeze-drying in the absence of skim milk, which might be explained by the protective effect of the drying medium. Only P. acidilactici isolates were demonstrated to have antimicrobial activity against the tested Listeria monocytogenes strains, which was also retained after freeze-drying.