Background: Producing bacteriocins is a common trait of Lactic Acid bacteria. Bacteriocins are small antimicrobial peptides produced by bacteria to inhibit the growth of competitors. Bacteriocin production of the opportunistic pathogen Streptococcus anginosus has so far not been systemically investigated. Here we identified a bacteriocin of S. anginosus, called Angicin and characterized its properties.
Methods: A strain collection of 95 clinical S. anginosus isolates was screened for bacteriocin production via a radial diffusion assay. By targeted genetic mutagenesis of bacteriocin producing strains the responsible bacteriocin gene was identified and the corresponding peptide was synthesized.
Results: S. anginosus BSU 1211 produces the class IId bacteriocin Angicin which is active against streptococci, listeria and Vancomycin-resistant Enterococcus faecium. The peptide remains active after exposure to high temperatures (90°C-1h). Located adjacent to the bacteriocin region is the streptococcal invasion locus (sil). This quorum sensing system regulates Angicin production in several S. anginosus isolates.
Conclusions: Angicin is a heat stable bacteriocin with an activity against clinically relevant bacteria like VRE and L. monocytogenes. Expression of Angicin is regulated via the quorum sensing system sil.