Enterococci from artisanal dairy products show high levels of adaptability.
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.
Carlos
Ana Rita
AR
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.
Santos
Jorge
J
Semedo-Lemsaddek
Teresa
T
Barreto-Crespo
Maria Teresa
MT
Tenreiro
Rogério
R
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