title: Diversity of Streptococcus thermophilus in bacteriocin production; inhibitory spectrum and occurrence of thermophilin genes.
abstract: The bacteriocin-producing Streptococcus thermophilus strains that can dominate in natural dairy ecosystems, may also enhance safety in products obtained from natural cultures. In this study, we sought to identify bacteriocin production and bacteriocin genes in 75 strains of dairy and plant origin. The strains were tested for antimicrobial activity against pathogens or pathogen models, spoiling bacteria, and lactic acid bacteria associated with dairy products. All strains moderately inhibited Staphylococcus aureus P310, none inhibited Listeria innocua LMG 11387(T) or Clostridium tyrobutyricum LMG 1285(T). In addition, 14 were active against one or more indicators in addition to S. aureus P310. Inhibition of other starter bacteria was more common than the inhibition of unwanted microorganisms. The involvement of a proteinaceous compound was ascertained in all cases. Results suggested that the selection of bacteriocinogenic S. thermophilus strains for use in biopreservation must take into account the effects exerted on other lactic acid bacteria. PCR detection of thermophilin genes proved unreliable in predicting antimicrobial activity. For S. thermophilus PRI36 and PRI45, with relevant inhibitory features, the identity of the bacteriocin genes present in the thermophilin 9 cluster was defined, thus revealing novel variants for this genome region.
authors.affiliation: Dipartimento di Biotecnologie, Università degli Studi di Verona, Strada le Grazie 15, Verona, Italy. franca.rossi@unimol.it
authors.forename: Franca
authors.initials: F
authors.lastname: Rossi
authors.forename: Marta
authors.initials: M
authors.lastname: Marzotto
authors.forename: Silvia
authors.initials: S
authors.lastname: Cremonese
authors.forename: Lucia
authors.initials: L
authors.lastname: Rizzotti
authors.forename: Sandra
authors.initials: S
authors.lastname: Torriani
mesh_terms: D001430:Bacteriocins / Q000096:biosynthesis / Q000235:genetics* / Q000494:pharmacology; D003013:Clostridium / Q000187:drug effects / Q000254:growth & development; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification*; D003611:Dairy Products / Q000382:microbiology; D005516:Food Microbiology; D005520:Food Preservatives / Q000494:pharmacology; D005798:Genes, Bacterial; D014644:Genetic Variation; D008087:Listeria / Q000187:drug effects / Q000254:growth & development; D005810:Multigene Family; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D048249:Streptococcus thermophilus / Q000235:genetics* / Q000378:metabolism
chemical_list: D001430:Bacteriocins; D004269:DNA, Bacterial; D005520:Food Preservatives