Molecular characterization of aureocin 4181: a natural N-formylated aureocin A70 variant with a broad spectrum of activity.

Bacteriocins are ribosomally synthesized antimicrobial peptides produced by prokaryotes. Here, the molecular characterization of aureocin 4181, a bacteriocin produced by Staphylococcus aureus 4181, a strain involved in bovine mastitis, is presented. Aureocin 4181 gene cluster (aurRID1CBAT) was mined from scaffold 15 of the draft genome of its producer strain. Three (AurABC) out of the four structural peptides of aureocin 4181 are identical to those of aureocin A70, except for AurD1 of aureocin 4181, which showed a conservative substitution of Leu29 to Phe29 when compared to AurD of aureocin A70. According to molecular mass determination and peptide sequencing, combined with genome sequencing data, aureocin 4181 is an N-formylated variant of aureocin A70. The analysis of its antimicrobial spectrum was extended to include strains of the two major contagious pathogens involved in bovine mastitis, S. aureus and Streptococcus agalactiae. Aureocin 4181 exhibited a striking activity against S. aureus, inhibiting most strains tested. Besides having a broader spectrum of activity, aureocin 4181 exhibited a stronger bacteriolytic action against the target strains and proved to be from two- to fourfold more active than aureocin A70 against S. aureus. Aureocin 4181 has potential to become an alternative drug for prevention and control of mastitic staphylococci, a pathogen that imposes a huge economic burden to dairy industry worldwide. It also represents the third four-component bacteriocin described in the literature, the second in staphylococci.

Draft genome sequence of Enterococcus faecium E86, a strain producing broad-spectrum antimicrobial peptides: Description of a novel bacteriocin immunity protein and a novel sequence type.

OBJECTIVES: The aim of this study was to report the draft genome sequence of the bacteriocinogenic strain Enterococcus faecium E86. Bacteriocins are prokaryotic peptides or proteins with antimicrobial activity. The genome information may contribute to the identification of enterocins produced by this strain that exhibit inhibitory activity against the foodborne pathogen Listeria monocytogenes and vancomycin-resistant enterococci (VRE) involved in human infections, among other bacterial genera and species. METHODS: An Illumina MiSeq platform was used for genome sequencing. De novo assembly of 5 735 838 paired-end reads was done using the A5-miseq pipeline, yielding >300-fold average genome coverage. Genome annotation was performed by the RAST server, and mining of the bacteriocinogenic gene clusters was done using the BAGEL3 and antiSMASH v.4 platforms. RESULTS: The total scaffold size was determined to be 2 689 107 bp, approximately 2.7 Mbp, featuring a G + C content of 38.1%. The genome contains 2858 coding sequences and 74 RNA genes. Genome analyses revealed the presence of: 30 genes involved in drug resistance; 2 bacteriocinogenic gene clusters (for enterocin P and enterocin TW21); EntiTW21, a novel bacteriocin immunity protein and a novel multilocus sequence type (ST1500). CONCLUSION: This work highlights the potential biotechnological application of this strain for the production of enterocin P, a bacteriocin that can be employed in the food industry as a biopreservative against L. monocytogenes and as an alternative to classical antibiotics against VRE.