RESUMO
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 degrees 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.
Assuntos
Bacteriocinas/farmacologia , Enterococcus/fisiologia , Microbiologia de Alimentos , Silagem/microbiologia , Zea mays/microbiologia , Bacillus/efeitos dos fármacos , Hidrocarbonetos Aromáticos com Pontes/análise , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Clostridium/efeitos dos fármacos , Meios de Cultura , Eletroforese em Gel de Poliacrilamida/métodos , Enterococcus faecalis/fisiologia , Enterococcus faecium/fisiologia , Escherichia coli/efeitos dos fármacos , Focalização Isoelétrica/métodos , Listeria/efeitos dos fármacos , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/ultraestrutura , Microscopia Eletrônica/métodos , Plasmídeos/isolamento & purificação , Reação em Cadeia da Polimerase/métodos , Shigella/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/ultraestruturaRESUMO
A survey at a rural community in Oaxaca, Mexico revealed 30 (29%) out of 104 people tested are carriers of anti-Trypanosoma cruzi antibodies. This high prevalence of seropositivity signals an important parasite circulation. We did not studied people under 15 years of age, therefore we can not identify transmission in this area. A concomitant study of 12 lead showed that those who are seropositive had more EKG abnormalities as a group. Such findings could indicate the parasitic disease impact on community health.
