Comparison of the activities of the lantibiotics nisin and lacticin 3147 against clinically significant mycobacteria

The aim of this study was to use the microtitre alamarBlue assay to investigate and compare the antimycobacterial potential of the lantibiotics nisin and lacticin 3147 against a representative cohort of clinically significant mycobacteria, i.e. Mycobacterium tuberculosis H37Ra, Mycobacterium avium subsp. paratuberculosis (MAP) ATCC 19698 and Mycobacterium kansasii CIT11/06. Lacticin 3147 displayed potent activity against all strains of mycobacteria, with MIC₉₀ values (lowest concentration of lantibiotic that prevented growth of >90% of the bacterial population) of 60mg/L and 15mg/L for M. kansasii and MAP, respectively. Lacticin 3147 was particularly effective against M. tuberculosis H37Ra, with a MIC₉₀ value of 7.5mg/L. Nisin, although inhibitory, was generally less potent against all strains of mycobacteria, with MIC₉₀ values of 60mg/L for M. kansasii and >60mg/L for MAP and M. tuberculosis H37Ra. Thus, lacticin 3147 is a potent antimycobacterial peptide that shows superior activity compared with nisin at physiological pH.