文摘
A total of 424 Enterococcus spp. isolates from clinical samples (n = 398) and traditional Bulgarian artisanal cheeses (n = 26) were studied in order to evaluate the incidence and expression of bacteriocin genetic determinants. Structural genes coding for enterocin A (entA), enterocin P (entP), enterocin B (entB), enterocin AS-48 (as-48) and enterolysin A (entlA) were detected by polymerase chain reaction (PCR), while reverse transcription PCR was performed to establish the gene expression. Of the total isolates, 163 (38.4 %) were potentially bacteriocinogenic. The genes typical of Enterococcus faecium (entA, entB and entP) were found in 84.0, 8.4 and 15.1 % of the E. faecium isolates, respectively. Focusing on E. faecalis isolates, the frequencies of entlA and as-48 were 19.3 and 0.7 %, respectively. No significant differences in the gene presence between clinical and dairy isolates were ascertained. Bacteriocin genes were found to be expressed at transcriptional level in 83.4 % of the bacteriocinogenic Enterococcus spp. isolates: a single gene in 113 samples (69.3 %), two genes in 21 (12.9 %) and three genes in 2 isolates (1.2 %). The present investigation may serve as a basis for further studies for elucidating the spread of the bacteriocin genetic determinants in the two enterococcal populations (clinical and dairy). Keywords Enterococcus spp. Clinical isolates Isolates from artisanal cheeses Bacteriocin-encoding genes Incidence Gene expression