Strategies for the Isolation and Characterization of Antibacterial Lantibiotics

Lantibiotics are biologically active peptides produced by several strains from the phyla Firmicutes and Actinobacteria . They are ribosomally synthesized and undergo posttranslational modifications that endow them with the characteristic (methyl)-lanthionine residues. As a result, lantibiotics contain a variable number of rings, each carrying one thioether link. Many lantibiotics inhibit growth of Gram-positive bacterial strains by interfering with peptidoglycan formation. Because they bind to the key intermediate lipid II at a site not affected by clinically used antibiotics, they are effective against multidrug-resistant strains. We describe a bioassay-based method suitable for finding antibacterial lantibiotics from actinomycete strains and provide selected procedures for characterizing newly discovered lantibiotics for their antibacterial properties.