Acid-adapted Listeria monocytogenes displays enhanced tolerance against the lantibiotics nisin and lacticin 3147.
Log-phase Listeria monocytogenes cells become tolerant to a variety of environmental stresses following acid adaptation at pH 5.5. We demonstrated that adapted cells also exhibit increased tolerance to nisin and, to a lesser extent, lacticin 3147. At nisin concentrations of 100 and 200 IU/ml the survival of acid-adapted cells was approximately 10-fold greater than nonadapted cells. However, acid adaptation had only a moderate effect on the tolerance of L. monocytogenes to lacticin 3147, a phenomenon that possibly reflects the distinct mode of action of this bacteriocin. Analysis of the fatty acid composition of the bacterial membrane indicated that straight-chain fatty acids C14:0 and C16:0 were significantly increased in acid-adapted cells while levels of C18:0 decreased. The results indicate that stress mechanisms that are induced in mildly acidic conditions provide protection against the antimicrobial action of bacteriocins. This increased resistance of acid-adapted L. monocytogenes could cause increased survival of this pathogen in food products in which nisin or other bacteriocins are used as preservatives.
van Schaik
W
W
Department of Microbiology and National Food Biotechnology Centre, University College, Cork, Ireland.
Gahan
C G
CG
Hill
C
C
D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000494:pharmacology; D001430:Bacteriocins; D015169:Colony Count, Microbial; D004352:Drug Resistance, Microbial; D005227:Fatty Acids / Q000032:analysis; D005520:Food Preservatives / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D009561:Nisin / Q000494:pharmacology*
D001426:Bacterial Proteins; D001430:Bacteriocins; D005227:Fatty Acids; D005520:Food Preservatives; C082508:lacticin 481; D009561:Nisin