Enterococci from artisanal dairy products show high levels of adaptability

Int J Food Microbiol. 2009 Feb 15;129(2):194-9. doi: 10.1016/j.ijfoodmicro.2008.11.003. Epub 2008 Nov 14.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cheese / microbiology*
  • Colony Count, Microbial
  • Consumer Product Safety*
  • Dairy Products / microbiology
  • Enterococcus / growth & development*
  • Enterococcus faecalis / growth & development
  • Enterococcus faecalis / pathogenicity
  • Enterococcus faecium / growth & development
  • Enterococcus faecium / pathogenicity
  • Female
  • Food Contamination / analysis
  • Food Contamination / prevention & control
  • Food Microbiology
  • Humans
  • Kinetics
  • Milk / microbiology*
  • Probiotics
  • Sheep
  • Species Specificity