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Production of enterocin A by Enterococcus faecium MMRA isolated from 'Rayeb', a traditional Tunisian dairy beverage

A Rehaiem1, B Martínez, M Manai

  • 1Faculté des Sciences de Tunis, Département de Biologie, Laboratoire de Biochimie et Biologie Moléculaire, Campus Universitaire, Tunis, Tunisie.

Journal of Applied Microbiology
|October 21, 2009
PubMed
Abstract

Insights

A wild Enterococcus faecium strain from Tunisian fermented milk produces enterocin A, a heat-stable bacteriocin with potential for food preservation. This protein exhibits strong anti-Listeria activity and bactericidal action.

Area of Science:

  • Food Microbiology
  • Bacteriology
  • Biochemistry

Background:

  • Traditional fermented dairy products, like Tunisian 'Rayeb', often harbor uncharacterized wild bacterial strains.
  • Enterococcus faecium is a common inhabitant of fermented foods, with some strains producing bacteriocins.
  • Bacteriocins are antimicrobial peptides with potential applications in food preservation.

Purpose of the Study:

  • To characterize and purify a bacteriocin from a wild Enterococcus faecium strain isolated from Tunisian fermented milk.
  • To identify the bacteriocin and assess its properties and potential applications.

Main Methods:

  • Isolation and selection of Enterococcus faecium MMRA based on anti-Listeria activity.
  • Assessing bacteriocin properties: sensitivity to proteases, heat stability, pH range, and stability to various treatments (lipase, amylase, solvents, detergents, lyophilization, storage).
  • Purification using SDS-PAGE and identification via MALDI-TOF mass spectrometry after tryptic digestion.

Main Results:

  • Enterococcus faecium MMRA demonstrated strong anti-Listeria activity.
  • The bacteriocin was proteinaceous, highly heat-stable, active across a wide pH range (2-12), and stable after various treatments.
  • Partial purification revealed a 4-kDa active peptide identified as enterocin A.
  • The bacteriocin exhibited bactericidal action and was produced during the logarithmic growth phase.

Conclusions:

  • The inhibitory activity of Enterococcus faecium MMRA is attributed to the production of enterocin A.
  • This study reports the first isolation of an enterocin A-producing Enterococcus faecium from 'Rayeb'.
  • Enterocin A or the producing strain shows promise for biopreservation in fermented dairy products to improve hygienic quality.

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