Diversified transporters and pathways for bacteriocin secretion in gram-positive bacteria

Bacteriocins are ribosomally synthesised small antimicrobial peptides produced from a wide range of bacteria, and also rich sources for potential alternatives to traditional antibiotics. Many bacteriocins have highly specific antibacterial activity against target pathogens, even including drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. As the final and essential step during biosynthesis, the leader sequence removal and exportation of matured bacteriocin are lacking of research and therefore the last to be understood. In respect of production, bacteriocin precursor peptides are processed and exported by a group of membrane proteins from the ATP-binding cassette transporter family. The main aims of this article are to summarise knowledge till now on the leader signal and correlated transporters for bacteriocin secretion in gram-positive bacteria in a review for the first time, to introduce different strategies for higher production, and to offer new insights into many essential but still unanswered questions above for the purpose of more efficient bacteriocin utilisation.