Biochemical and genetic characterization of propionicin T1, a new bacteriocin from Propionibacterium thoenii

A collection of propionibacteria was screened for bacteriocin production. A new bacteriocin named propionicin T1 was isolated from two strains of Prop ionibacterium thoenii, This bacteriocin shows no sequence similarity to oth er bacteriocins, Propionicin T1 was active against all strains of Propionib acterium acidipropionici, Propionibacterium thoenii, and Propionibacterium jensenii tested and also against Lactobacillus sake NCDO 2714 but showed no activity against Propionibacterium freudenreichii, The baeteriocin was pur ified, and the N-terminal part of the peptide was determined with amino aci d sequencing, The corresponding gene pctA was sequenced, and this revealed that propionicin T1 is produced as a prebacteriocin of 96 amino acids with a typical sec leader, which is processed to give a mature bacteriocin of 65 amino acids. An open reading frame encoding a protein of 424 amino acids w as found 68 nucleotides downstream the stop codon of pctA, The N-terminal p art of this putative protein shows strong similarity with the ATP-binding c assette of prokaryotic and eukaryotic ABC transporters, and this protein ma y be involved in self-protection against propionicin TL, Propionicin T1 is the first bacteriocin from propionibacteria that has been isolated and furt her characterized at the molecular level.