title: Enterococci from artisanal dairy products show high levels of adaptability.
abstract: 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.
authors.affiliation: Universidade de Lisboa, Faculdade de Ciências, Centro para a Biodiversidade, Genómica Integrativa e Funcional (BioFIG), Instituto de Ciência Aplicada e Tecnologia, 1749-016 Lisboa, Portugal.
authors.forename: Ana Rita
authors.initials: AR
authors.lastname: Carlos
authors.forename: Jorge
authors.initials: J
authors.lastname: Santos
authors.forename: Teresa
authors.initials: T
authors.lastname: Semedo-Lemsaddek
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Barreto-Crespo
authors.forename: Rogério
authors.initials: R
authors.lastname: Tenreiro
mesh_terms: D000818:Animals; D002611:Cheese / Q000382:microbiology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D003611:Dairy Products / Q000382:microbiology; D016983:Enterococcus / Q000254:growth & development*; D013293:Enterococcus faecalis / Q000254:growth & development / Q000472:pathogenicity; D016984:Enterococcus faecium / Q000254:growth & development / Q000472:pathogenicity; D005260:Female; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005516:Food Microbiology; D006801:Humans; D007700:Kinetics; D008892:Milk / Q000382:microbiology*; D019936:Probiotics; D012756:Sheep; D013045:Species Specificity