• Production of multiple bacteriocins from a single locus by gastrointestinal strains of Lactobacillus salivarius

      O'Shea, Eileen F.; O'Connor, Paula M.; Raftis, Emma J.; O'Toole, Paul W.; Stanton, Catherine; Cotter, Paul D.; Ross, R Paul; Hill, Colin (American Society for Microbiology, 2011-10-07)
      Bacteriocins produced by Lactobacillus salivarius isolates derived from gastrointestinal origin have previously demonstrated efficacy for in vivo protection against Listeria monocytogenes infection. In this study, comparative genomic analysis was employed to investigate the intraspecies diversity of seven L. salivarius isolates of human and porcine intestinal origin, based on the genome of the well characterised bacteriocin-producing strain L. salivarius UCC118. This revealed a highly conserved megaplasmid-encoded gene cluster in these strains involved in the regulation and secretion of two-component class IIb bacteriocins. However, considerable intraspecific variation was observed in the structural genes encoding the bacteriocin peptides. These ranged from close relatives of abp118 such as salivaricin P, which differs by 2 amino acids, to completely novel bacteriocins such as salivaricin T, which is characterized in this study. Salivaricin T inhibits closely related lactobacilli and bears little homology to previously characterized salivaricins. Interestingly, the two peptides responsible for salivaricin T activity, SalTα and SalTβ, share considerable identity with the component peptides of thermophilin 13, a bacteriocin produced by Streptococcus thermophilus. Furthermore, the salivaricin locus of strain DPC6488 also encodes an additional novel one-component class IId anti-listerial bacteriocin, salivaricin L. These findings suggest a high level of redundancy in the bacteriocins that can be produced by intestinal L. salivarius isolates using the same enzymatic production and export machinery. Such diversity may contribute to their ability to dominate and compete within the complex microbiota of the mammalian gut.
    • Subspecies diversity in bacteriocin production by intestinal Lactobacillus salivarius strains

      O'Shea, Eileen F.; O'Connor, Paula M.; Raftis, Emma J.; O'Toole, Paul W.; Stanton, Catherine; Cotter, Paul D.; Ross, R Paul; Hill, Colin (Landes Bioscience, 2012-10)
      A recent comparative genomic hybridisation study in our laboratory revealed considerable plasticity within the bacteriocin locus of gastrointestinal strains of Lactobacillus salivarius. Most notably these analyses led to the identification of two novel unmodified bacteriocins salivaricin L and salivaricin T produced by the neonatal isolate L. salivarius DPC6488 with immunity, regulatory and export systems analogous to those of abp118, a two-component bacteriocin produced by the well characterized reference strain L. salivarius UCC118. In this addendum we discuss the intraspecific diversity of our seven bacteriocin-producing L. salivarius isolates on a genome-wide level, and more specifically, with respect to their salivaricin loci.