Bacterial antimicrobial peptides, also known as bacteriocins, are peptides produced by bacteria and display inhibitory activity against closely related bacteria. They make up a heterogeneous family in terms of heat stability, molecular mass, mode of release and action, microbial target, and mechanism conferring protection to the producing strain. Much research has been done to better characterize these compounds because of their potential biotechnological use either as food preservatives or therapeutic agents. Up to now, nisin and pediocin PA1/AcH have found widespread use as food preservatives.We collected 407 bacteriocins including newly reported sequences from literature and Uniprot, and accordingly established a new database. Detailed in-vitro and in-vivo antibacterial data of bacteriocins which are deficient in other antimicrobial peptide databases are included in our database. The database is aimed at promoting development of bacteriocins as therapeutic agents against animal and human pathogens.
Lactic acid bacteria (LAB) bacteriocins can be grouped on the basis of structure, but also on the basis of mode of action. Some members of the class I (or lantibiotic) bacteriocins, such as nisin, have been shown to have a dual mode of action. They can bind to lipid II, the main transporter of peptidoglycan subunits from the cytoplasm to the cell wall, and therefore prevent correct cell wall synthesis, leading to cell death. Furthermore, they can use lipid II as a docking molecule to initiate a process of membrane insertion and pore formation that leads to rapid cell death. A two-peptide lantibiotic, such as lacticin 3147, can have these dual activities distributed across two peptides, whereas mersacidin has only the lipid-II-binding activity, but does not form pores. In general, the class II peptides have an amphiphilic helical structure, which allows them to insert into the membrane of the target cell, leading to depolarisation and death. Large bacteriolytic proteins (here called bacteriolysins, formerly class III bacteriocins), such as lysostaphin, can function directly on the cell wall of Gram-positive targets, leading to death and lysis of the target cell.
Bacteriocins can also be used to promote quality, rather than simply to prevent spoilage or safety problems. For example, bacteriocins can be used to control adventitious non-starter flora such as non-starter lactic acid bacteria (NSLAB) in cheese and wine. The uncontrolled growth of NSLAB can cause major economic losses owing to calcium-d-lactate formation and slit defects in cheeses, and the production of detrimental compounds in wine. Bacteriocinproducing starters and adjuncts (one- or two-strain strategies) have been found to significantly reduce these problems. What's more, the non-toxicity of lantibiotics and their activity against Gram-positive human and animal pathogens has led to research investigating their potential clinical application.In particular, the elucidation of the precise mechanism of action of some lantibiotics and their activity against multidrugresistant pathogens by a novel mechanism makes them an attractive option as possible therapeutic agents.