title: Control of tyramine and histamine accumulation by lactic acid bacteria using bacteriocin forming lactococci.
abstract: The aim of this study was to evaluate the competitive effects of three bacteriocin producing strains of Lactococcus lactis subsp. lactis against two aminobiogenic lactic acid bacteria, i.e. the tyramine producing strain Enterococcus faecalis EF37 and the histamine producing strain Streptococcus thermophilus PRI60, inoculated at different initial concentrations (from 2 to 6 log cfu/ml). The results showed that the three L. lactis subsp. lactis strains were able to produce bacteriocins: in particular, L. lactis subsp. lactis VR84 and EG46 produced, respectively, nisin Z and lacticin 481, while for the strains CG27 the bacteriocin has not been yet identified, even if its peptidic nature has been demonstrated. The co-culture of E. faecalis EF37 in combination with lactococci significantly reduced the growth potential of this aminobiogenic strain, both in terms of growth rate and maximum cell concentration, depending on the initial inoculum level of E. faecalis. Tyramine accumulation was strongly reduced when E. faecalis EF37 was inoculated at 2 log cfu/ml and, to a lesser extent, at 3 log cfu/ml, as a result of a lower cell load of the aminobiogenic strain. All the lactococci were more efficient in inhibiting streptococci in comparison with E. faecalis EF37; in particular, L. lactis subsp. lactis VR84 induced the death of S. thermophilus PRI60 and allowed the detection of histamine traces only at higher streptococci inoculum levels (5-6 log cfu/ml). The other two lactococcal strains did not show a lethal action against S. thermophilus PRI60, but were able to reduce its growth extent and histamine accumulation, even if L. lactis subsp. lactis EG46 was less effective when the initial streptococci concentration was 5 and 6 log cfu/ml. This preliminary study has clarified some aspects regarding the ratio between bacteriocinogenic strains and aminobiogenic strains with respect to the possibility to accumulate BA and has also showed that different bacteriocins can have different effects on BA production on the same strain. This knowledge is essentially aimed to use bacteriocinogenic lactococci as a predictable strategy against aminobiogenic bacteria present in cheese or other fermented foods.
authors.affiliation: Centro Interdipartimentale di Ricerca Industriale Agroalimentare, Università degli Studi di Bologna, Sede di Cesena, Piazza Goidanich 60, 47521, Cesena (FC), Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Tabanelli
authors.affiliation: Centro Interdipartimentale di Ricerca Industriale Agroalimentare, Università degli Studi di Bologna, Sede di Cesena, Piazza Goidanich 60, 47521, Cesena (FC), Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Montanari
authors.affiliation: Dipartimento di Scienze e Tecnologie Agro-alimentari, Università degli Studi di Bologna, Sede di Cesena, Piazza Goidanich 60, 47521, Cesena (FC), Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Bargossi
authors.affiliation: Centro Interdipartimentale di Ricerca Industriale Agroalimentare, Università degli Studi di Bologna, Sede di Cesena, Piazza Goidanich 60, 47521, Cesena (FC), Italy; Dipartimento di Scienze e Tecnologie Agro-alimentari, Università degli Studi di Bologna, Sede di Cesena, Piazza Goidanich 60, 47521, Cesena (FC), Italy.
authors.forename: Rosalba
authors.initials: R
authors.lastname: Lanciotti
authors.affiliation: Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 8, 37134, Verona (VR), Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Gatto
authors.affiliation: Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 8, 37134, Verona (VR), Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Felis
authors.affiliation: Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 8, 37134, Verona (VR), Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Torriani
authors.affiliation: Centro Interdipartimentale di Ricerca Industriale Agroalimentare, Università degli Studi di Bologna, Sede di Cesena, Piazza Goidanich 60, 47521, Cesena (FC), Italy; Dipartimento di Scienze e Tecnologie Agro-alimentari, Università degli Studi di Bologna, Sede di Cesena, Piazza Goidanich 60, 47521, Cesena (FC), Italy. Electronic address: fausto.gardini@unibo.it.
authors.forename: Fausto
authors.initials: F
authors.lastname: Gardini
mesh_terms: D000898:Antibiosis / Q000502:physiology*; D013293:Enterococcus faecalis / Q000254:growth & development / Q000502:physiology*; D005516:Food Microbiology; D006632:Histamine / Q000378:metabolism*; D013294:Lactococcus lactis / Q000502:physiology*; D048249:Streptococcus thermophilus / Q000254:growth & development / Q000502:physiology*
chemical_list: D006632:Histamine
keywords: Bacteriocins; Biogenic amines; Competition; Enterococcus faecalis; Lactococcus lactis; Streptococcus thermophilus