Description of two Enterococcus strains isolated from traditional Peruvian artisanal-produced cheeses with a bacteriocin-like inhibitory activity

• Published in: Biotechnologie, agronomie, société et environnement Vol. 13; no. 3; pp. 349 - 356
• Main Authors: Galvez, A A, Dubois-Dauphin, R, Ghalfi, H, Campos, D, Thonart, P
• Format: Journal Article
• Language: French
• Published: 01.01.2009
• Subjects: Bacteria; Enterococcus; Enterococcus faecium; Enterococcus mundtii; Listeria monocytogenes
• ISSN: 1370-6233

The aim of this work was to isolate and to characterize strains of lactic acid bacteria (LAB) with bacteriocin-like inhibitory activity from 27 traditional cheeses artisanal-produced obtained from different Peruvian regions. Twenty Gram super(+) and catalase-negative strains among 2,277 isolates exhibited bacteriocin-like inhibitory activity against Listeria monocytogenes CWBI-B2232 as target strain. No change in inhibitory activity was observed after organic acid neutralization and treatment with catalase of the cell-free supernatant (CFS). The proteinic nature of the antimicrobial activity was confirmed for the twenty LAB strains by proteolytic digestion of the CFS. Two strains, CWBI-B1431 and CWBI-B1430, with the best antimicrobial activity were selected for further researches. These strains were taxonomically identified by phenotypic and genotypic analyses as Enterococcus mundtii (CWBI-B1431) and Enterococcus faecium (CWBI-B1430). The two strains were sensitive to vancomycin (MIC < 2 kg; ml super(-1)) and showed absence of haemolysis.Original Abstract: L'objectif de ce travail a ete d'isoler et de caracteriser des bacteries lactiques aux proprietes antimicrobiennes issues de 27 echantillons de fromages artisanaux d'origine peruvienne. Un total de 20 souches de bacteries Gram super(+) et catalase negative avec activite du type bacteriocine contre Listeria monocytogenes CWBI-B2232 ont ete isolees a partir d'une collection de 2277 isolats. L'activite antimicrobienne est maintenue apres neutralisation des acides organiques (acide lactique et acetique) et du peroxyde d'hydrogene. La nature proteique des composes inhibiteurs a ete confirmee pour les 20 souches selectionnees, par digestion proteolytique des surnageants de culture. Les souches referencees CWBI-B1431 et CWBI-B1430 sont celles qui presentent les activites antibacteriennes les plus importantes. Elles ont fait l'objet une caracterisation polyphasique (genotypique et phenotypique). Sur cette base, CWBI-B1431 et CWBI-B1430 ont ete identifiees, respectivement, comme Enterococcus mundtii et Enterococcus faecium. Ces deux souches sont sensibles a l'antibiotique vancomycine (CMI < 2 kg; ml super(-1)) et ont montre l'absence d'activite hemolytique.