Enterococci from artisanal dairy products show high levels of adaptability
- Autores: Ana Rita Carlos, Jorge Santos, Teresa Semedo Lemsaddek, Maria Teresa Barreto Crespo, Rogério Tenreiro
- Localización: International journal of food microbiology, ISSN 0168-1605, Vol. 129, Nº. 2, 2009, págs. 194-199
- Idioma: inglés
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Resumen
Enterococci are ubiquitous organisms able to promote both health (fermented food/probiotics) and illness (human/animal infections). Disturbingly, several enterococcal species commonly found in artisanal cheeses, such as Enterococcus faecalis and E. faecium, are being increasingly established as causes of infection, posing a problem for food safety. In this study enterococci from ewe's milk and cheese were compared to clinical and reference strains by growth in media simulating environmental colonization and infection sites: 2YT, BHI, skim milk, urine and rabbit serum at different pHs, NaCl concentrations and temperatures. Growth curves were obtained with Microbiology Workstation Bioscreen C® and used to calculate relative indexes – RIs – (based on absorbance, lag phase and specific growth rate) for each strain and environmental condition. Similar or higher RIs were obtained for food strains growing in infection-related environments when compared to clinical ones, revealing their ability to adapt and grow in these conditions. A dendrogram built using Pearson's correlation coefficient and a PCA analysis clustered the strains regardless of their origin or species allocation, suggesting a strain-specific mode of growth and a high environmental adaptability of enterococcal strains. These evidences turn essential the evaluation of strains to be used as starters or probiotics.
