CERELA   05438
CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Characterization of mundticin CRL1656, a bacteriocin produced by Enterococcus mundtii CRL 1656 isolated from a healthy cow stripping milk sample
Autor/es:
ESPECHE, MARÍA CAROLINA; SAAVEDRA, LUCILA; NADER-MACÍAS, MARÍA ELENA; SESMA, FERNADO
Lugar:
Saint Malo, Francia
Reunión:
Simposio; Second International Symposium on Antimicrobial Peptides; 2009
Institución organizadora:
INRA
Resumen:
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M. Carolina Espeche, Lucila Saavedra, M. Elena Nader-Macías and Fernando Sesma, CERELA-CONICET, Chacabuco 145, 4000, San Miguel de Tucumán, Argentina. Email: fnader@cerela.org.ar, fsesma@cerela.org.ar Bacteriocins are antimicrobial compounds of proteinaceus nature that are produced by almost all bacterial genera analyzed up to date. Lactic Acid Bacteria (LAB) group is not the exception, and includes the genus Enterococcus, which has been shown to be very prolific with respect to bacteriocin production. Among the enterococcal species, E. faecalis, E. faecium and E. mundtii are the predominant bacteriocinogenic species. Enterococcus mundtii has exceptionally been isolated from human sources, and it is associated mainly with vegetables, artisanal cheeses and environment of some dairy farms. Due to the absence of pathogenicity factors, some strains are being assayed as microbial feed additives and also as human probiotic. In a recent work, we have isolated three bacteriocinogenic LAB strains from the udder and the teat canal of healthy adult cows.[1] One of these isolated strains, E. mundtii CRL 1656 was shown to produce a bacteriocin-like substance. The antimicrobial peptide produced by this strain inhibited E. mundtii CRL 35, which synthesizes a class IIa bacteriocin, enterocin CRL35 (also known as mundticin). This sensibility pattern induced us to think that the bacteriocin produced by E. mundtii CRL 1656 could be different than mundticin. Therefore, the objective of the present work was to characterize the antimicrobial peptide produced by this strain.  By using designed primers based on enterocin CRL35 sequence and a primer walking strategy, we have identified the mundticin CRL1656 biosynthesis cluster. Although the genetic organization is similar to that of enterocin CRL35 and mundticin KS, the analysis of the structural gene and its coding sequence revealed that the mature peptide possess two conservative amino acid changes in the C- terminus region of the antibacterial peptide. Besides, the leader peptide presents some modification when compared with enterocin CRL35, and also shows the typical double Gly, which is the processing site for the ABC exportation.  Regarding enterocin CRL1656 antimicrobial spectrum, preliminary studies demonstrated that it is similar to that of enterocin CRL35 but with an increased size of inhibition halos. Cross-testing these two strains against each other showed that mundticin CRL1656 is active against E. mundtii CRL 35, although enterocin CRL35 is not active against this strain. At present, more studies are being performed to complete the characterization of the antimicrobial peptide mundticin CRL1656. References [1] Espeche MC, Otero MC, Sesma F, Nader-Macías ME. (2009) Screening of surface properties and antagonistic substances production by lactic acid bacteria isolated from the mammary gland of healthy and mastitic cows. Vet Microbiol 135: 346-357.