Spontaneous resistance in Lactococcus lactis IL1403 to the lantibiotic lacticin 3147

Abstract

The ability and frequency at which target organisms can develop resistance to bacteriocins is a crucial consideration in designing and implementing bacteriocin-based biocontrol strategies. Lactococcus lactis ssp. lactis IL1403 was used as a target strain in an attempt to determine the frequency at which spontaneously resistant mutants are likely to emerge to the lantibiotic lacticin 3147. Following a single exposure to lacticin 3147, resistant mutants only emerged at a low frequency (10-8-10-9) and were only able to withstand low levels of the bacteriocin (100 AU mL-1). However, exposure to increasing concentrations, in a stepwise manner, resulted in the isolation of eight mutants that were resistant to moderately higher levels of lacticin 3147 (up to 600 AU mL-1). Interestingly, in a number of cases cross-resistance to other lantibiotics such as nisin and lacticin 481 was observed, as was cross-resistance to environmental stresses such as salt. Finally, reduced adsorption of the bacteriocin in to the cell was documented for all resistant mutants. © 2006 Federation of European Microbiological Societies Published by Blackwell Publishing Ltd. All rights reserved.