Technological and molecular characterisation of enterococci isolated from north-west Italian dairy products
2006
Morandi, S. | Brasca, M. | Andrighetto, C. | Lombardi, A. | Lodi, R.
In the present study, 68 enterococcal isolates collected from dairy products in north-west Italy were characterised by randomly amplified polymorphic DNA-PCR (RAPD-PCR) and by their technologically relevant biochemical properties. After the comparison of RAPD-PCR profiles with the profiles of the enterococcal type strains, isolates were assigned to the species Enterococcus faecalis (35 isolates), E. faecium (27 isolates) and E. durans (6 isolates). Phenotypic identification based on carbohydrate fermentation profile galleries gave different results from RAPD-PCR in 17.6% of the cases (10 E. faecium and 2 E. durans isolates). With respect to biochemical activities, the majority of the strains displayed weak acidification activity in milk. High values for redox activity were detected for 80% of E. faecalis isolates, while E. faecium provided the most lipolytic species. Proteolytic activity was generally low, except for 10 E. faecalis isolates that displayed values >or= 0.5 mg tyrosine 5mL⁻¹ of milk. None of the isolates carried vanA or vanB (vancomycin resistance) genetic determinants.
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