Enterococci are common constituents of dairy products such as raw milk cheeses, in which it is believed that they contribute to the development of some of their organoleptic properties. A total of 434 enterococci, isolated from dairy products were screened for the production of antimicrobial peptides against L. monocytogenes and S. aureus. Enterocins production was detected in 43 strains (10%), belonging to the species E. durans, E. faecalis and E. faecium. Investigation of enterocin genes by PCR amplification revealed the presence of entP and bac31 genes among E. durans isolates, whereas a high incidence of entP and entA genes was detected in E. faecium strains. The structural genes of enterocin AS-48 was widely distributed among E. faecalis isolates. In addition, a strain belonging to E. faecalis species harboured the entQ gene, whose presence was no previously reported in enterococci isolated from dairy products.
Gli enterococchi sono microrganismi comunemente presenti nei prodotti caseari a latte crudo e contribuiscono positivamente alla definizione delle loro caratteristiche organolettiche. Lo scopo principale di questo lavoro é stato quello di valutare l'attività inibente di enterococchi provenienti da prodotti lattiero- caseari del nord Italia nei confronti di Listeria monocytogenes e Staphylococcus aureus. Quarantatre ceppi su 434 (10%), appartenenti alle specie Enterococcus durans, E. faecalis ed E. faecium, sono risultati in grado di inibire L. monocytogenes e/o S. aureus. Le reazione di PCR hanno evidenziato che fra i ceppi appartenenti alla specie E. durans sono ampiamente diffusi i geni codificanti per enterocina P e batteriocina 31, mentre in E. faecium prevalgono i geni entP ed entA. Nella specie E. faecalis, la quasi totalità dei ceppi ha evidenziato la presenza del gene entAS-48. In un ceppo di E. faecalis si é riscontrata la presenza dell'enterocina Q, mai rilevata prima in isolati provenienti dal comparto lattiero-caseario.
Evaluation of antimicrobial activity and enterocins genes in enterococci isolated from north italian dairy products
Morandi Stefano;Brasca Milena;Silvetti Tiziana;Lodi Roberta
2010
Abstract
Enterococci are common constituents of dairy products such as raw milk cheeses, in which it is believed that they contribute to the development of some of their organoleptic properties. A total of 434 enterococci, isolated from dairy products were screened for the production of antimicrobial peptides against L. monocytogenes and S. aureus. Enterocins production was detected in 43 strains (10%), belonging to the species E. durans, E. faecalis and E. faecium. Investigation of enterocin genes by PCR amplification revealed the presence of entP and bac31 genes among E. durans isolates, whereas a high incidence of entP and entA genes was detected in E. faecium strains. The structural genes of enterocin AS-48 was widely distributed among E. faecalis isolates. In addition, a strain belonging to E. faecalis species harboured the entQ gene, whose presence was no previously reported in enterococci isolated from dairy products.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
