Indigenous lactic acid bacteria-producing bacteriocins could enhance the microbiological safety of traditional cheeses. This study aimed to detect bacteriocinogenic strains among 35 Lactobacillus plantarum isolated from artisanal, raw sheep-milk cheeses. The isolates were identified by API 50 CHL and species-specific PCR. As displayed by agar well-diffusion assay, the cell-free supernatant of L. plantarum LpU4 showed the highest antimicrobial activity against Enterococcus faecalis JH2-2. The activity was not detected after treatment with proteinase K, pepsine and pronase. An active peptide band was shown by tricine–sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis and subsequent bioassay. MALDI-TOF analysis revealed a protein of 4,866.7 Da, having no homology with other known bacteriocins. The novel bacteriocin (named plantaricin LpU4) was heat stable (121 °C for 15 min), unaffected by chemicals as Tween 20, SDS, Triton ×100, EDTA, NaCl and exposure to a wide range of pH. The synthetic machinery encoding for the plantaricin was plasmid-located, as deduced by plasmids curing. Activity spectrum included several lactic acid bacteria and Staphylococcus aureus strains having antibiotic resistance phenotype. Plantaricin LpU4 showed a bacteriostatic mode of action and an enhanced activity at acidic pHs. Maximal production (3,200 AU.mL−1) was reached during the late exponential phase of growth of L. plantarum LpU4. Relatively low temperature (15–25 °C) and initial pH between 5.5 and 6.2 increased the production. Since L. plantarum LpU4 produced the bacteriocin under experimental conditions mimicking the cheese environment, it could be considered a promising candidate for use as biopreservative in traditional cheese.

A novel bacteriocin produced by Lactobacillus plantarum LpU4 as a valuable candidate for biopreservation in artisanal raw milk cheese

MILIONI, CARLA;TURCHI, BARBARA;FRATINI, FILIPPO;CERRI, DOMENICO;
2015-01-01

Abstract

Indigenous lactic acid bacteria-producing bacteriocins could enhance the microbiological safety of traditional cheeses. This study aimed to detect bacteriocinogenic strains among 35 Lactobacillus plantarum isolated from artisanal, raw sheep-milk cheeses. The isolates were identified by API 50 CHL and species-specific PCR. As displayed by agar well-diffusion assay, the cell-free supernatant of L. plantarum LpU4 showed the highest antimicrobial activity against Enterococcus faecalis JH2-2. The activity was not detected after treatment with proteinase K, pepsine and pronase. An active peptide band was shown by tricine–sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis and subsequent bioassay. MALDI-TOF analysis revealed a protein of 4,866.7 Da, having no homology with other known bacteriocins. The novel bacteriocin (named plantaricin LpU4) was heat stable (121 °C for 15 min), unaffected by chemicals as Tween 20, SDS, Triton ×100, EDTA, NaCl and exposure to a wide range of pH. The synthetic machinery encoding for the plantaricin was plasmid-located, as deduced by plasmids curing. Activity spectrum included several lactic acid bacteria and Staphylococcus aureus strains having antibiotic resistance phenotype. Plantaricin LpU4 showed a bacteriostatic mode of action and an enhanced activity at acidic pHs. Maximal production (3,200 AU.mL−1) was reached during the late exponential phase of growth of L. plantarum LpU4. Relatively low temperature (15–25 °C) and initial pH between 5.5 and 6.2 increased the production. Since L. plantarum LpU4 produced the bacteriocin under experimental conditions mimicking the cheese environment, it could be considered a promising candidate for use as biopreservative in traditional cheese.
2015
Milioni, Carla; Martínez, B.; Degl’Innocenti, S.; Turchi, Barbara; Fratini, Filippo; Cerri, Domenico; Fischetti, R.
File in questo prodotto:
File Dimensione Formato  
2015 Milioni et al Bacteriocin.pdf

solo utenti autorizzati

Tipologia: Versione finale editoriale
Licenza: NON PUBBLICO - Accesso privato/ristretto
Dimensione 1.07 MB
Formato Adobe PDF
1.07 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/749867
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 25
  • ???jsp.display-item.citation.isi??? 24
social impact