Partial characterization of enterocin MR99 from a corn silage isolate of Enterococcus faecalis

Abstract

Aims: To assess the inhibitory activity on Gram‐positive and Gram‐negative bacteria of several species of enterococci recovered from a natural corn silage. Methods and Results: The inhibitory activity of strains of Enterococcus faecalis (58), Enterococcus faecium (35), Enterococcus gallinarum (3) and Enterococcus casseliflavus (4) were studied employing indicator strains from various sources (clinical, food and ATCC). Enterococcus faecalis MR99, the only strain with inhibitory activity, inhibited other enterococci, Listeria spp., Staphylococcus aureus, Clostridium spp., Bacillus spp., Escherichia coli, Shigella sonnei and Shigella flexneri. The bacterium contained only one conjugative pheromone‐responsive plasmid. The partially chromatography‐purified MR99 enterocin (PPE) had a molecular weight of approx. 5000 Da and a pI of 6·2, was sensitive to proteolytic enzymes and could be extracted in benzene and butanol. It appeared stable to adjustment of pH 4·0, 5·0, 6·0, 7·0 and 8·0 and was resistant to heat. Inactivation was at 15 min at 121°C. Enterocin MR99 was bactericidal on strains of Listeria monocytogenes, Staph. aureus, and bovine mastitis agents, it was bacteriostatic on E. coli. Although enterocins MR99 and AS48 have inhibitory activity on Gram‐negative bacilli, PCR studies demonstrated a lack of relationship between them. Conclusions: The active component had a protein nature, was resistant to heat and presented a wide inhibitory spectrum. Significance and Impact of the Study: The biological properties of Ent. faecalis MR99 suggest that this strain merits further investigations so it can be applied in human and veterinary health programmes.

Purification and characterization of enterocin FH 99 produced by a faecal isolate Enterococcus faecium FH 99

“…Like the fi ndings of other authors [26], our fi ndings also suggested that bacteriocins of LAB are primarily active against Gram-positive organisms. A few reports, however, do indicate enterocins to be active against Gram-negative bacteria such as E. coli [27,28], Shigella sonnei, Shigella fl exneri [29] and Vibrio cholera [30]. But in the present investigation, bacteriocin of E. faecium FH 99 was not found to be effective against Gram-negative organisms.…”

In vitro and in vivo effects of Enterococcus faecalis CECT7121 on Toxocara canis

“…A decrease of this inhibitory effect was observed with the supernatant of Ef7121m (EIm) and with co-incubation with the mutant strain (EIIIm). The Ef7121 mutant strain lacks a plasmid that is present in the wild-type strain (Sparo et al 2006). Electrophoretic analysis of plasmid DNA demonstrated that Ef7121 contains only one plasmid, which is responsible for the production of antimicrobial peptide (AP, such as bacteriocin), a protein that possesses broad inhibitory activity against Gram-positive and Gram-negative bacteria (Sparo et al 2006).…”

“…The Ef7121 mutant strain lacks a plasmid that is present in the wild-type strain (Sparo et al 2006). Electrophoretic analysis of plasmid DNA demonstrated that Ef7121 contains only one plasmid, which is responsible for the production of antimicrobial peptide (AP, such as bacteriocin), a protein that possesses broad inhibitory activity against Gram-positive and Gram-negative bacteria (Sparo et al 2006). When the mutant strain was used, the effect on T. canis larval viability was reduced but a larvicidal property remained.…”

“…and mutant (lacking plasmid) E. faecalis CECT7121 (Ef7121m) strains were used (Sparo et al 2006). Both strains were cultured for 24 h at 35ºC in triptein soy agar (Laboratorios Britania, Buenos Aires).…”

“…However, they have been used successfully in animals for the treatment of parasitoses, such as cryptosporidiosis, giardiasis, trichinellosis and babesiosis (Alak et al 1999, Bautista-Garfias et al 2001, Humen et al 2005. In contrast, Dea-Ayuela et al (2008) (Sparo et al 2006). This strain can adhere and persist in the murine intestinal epithelium (Basualdo et al 2007).…”