Membranes of class IIa bacteriocin-resistant Listeria monocytogenes cells contain increased levels of desaturated and short-acyl-chain phosphatidylglycerols
Date
2002
Authors
Vadyvaloo, Viveka
Hastings J.W.
Van der Merwe M.J.
Rautenbach, Marina
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Abstract
A major concern in the use of class IIa bacteriocins as food preservatives is the well-documented resistance development in target Listeria strains. We studied the relationship between leucocin A, a class IIa bacteriocin, and the composition of the major phospholipid, phosphatidylglycerol (PG), in membranes of both sensitive and resistant L. monocytogenes strains. Two wild-type strains, L. monocytogenes B73 and 412, two spontaneous mutants of L. monocytogenes B73 with intermediate resistance to leucocin A (±2.4 and ±4 times the 50% inhibitory concentrations [IC50] for sensitive strains), and two highly resistant mutants of each of the wild-type strains (<500 times the IC50 for sensitive strains) were analyzed. Electrospray mass spectrometry analysis showed an increase in the ratios of unsaturated to saturated and short- to long-acyl-chain species of PG in all the resistant L. monocytogenes strains in our study, although their sensitivities to leucocin A were significantly different. This alteration in membrane phospholipids toward PGs containing shorter, unsaturated acyl chains suggests that resistant strains have cells with a more fluid membrane. The presence of this phenomenon in a strain (L. monocytogenes 412P) which is resistant to both leucocin A and pediocin PA-1 may indicate a link between membrane composition and class IIa bacteriocin resistance in some L. monocytogenes strains. Treatment of strains with sterculic acid methyl ester (SME), a desaturase inhibitor, resulted in significant changes in the leucocin A sensitivity of the intermediate-resistance strains but no changes in the sensitivity of highly resistant strains. There was, however, a decrease in the amount of unsaturated and short-acyl-chain PGs after treatment with SME in one of the intermediate and both of the highly resistant strains, but the opposite effect was observed for the sensitive strains. It appears, therefore, that membrane adaptation may be part of a resistance mechanism but that several resistance mechanisms may contribute to a resistance phenotype and that levels of resistance vary according to the type of mechanisms present.
Description
Keywords
Biological membranes, Cells, Esters, Fatty acids, Mass spectrometry, Mutagenesis, Phospholipids, Wild type strains, Bacteria, acyl coenzyme A desaturase, bacteriocin, fatty acid derivative, food preservative, leucocin a, membrane phospholipid, pediocin, pediocin pa 1, phosphatidylglycerol, sterculic acid methyl ester, unclassified drug, microbiology, adaptation, antibacterial activity, antibiotic resistance, article, bacterial membrane, controlled study, fatty acid desaturation, food preservation, lipid composition, Listeria monocytogenes, mass spectrometry, nonhuman, Bacteriocins, Cell Membrane, Drug Resistance, Bacterial, Fatty Acids, Monounsaturated, Inhibitory Concentration 50, Listeria monocytogenes, Microbial Sensitivity Tests, Phosphatidylglycerols, Phospholipids, Spectrometry, Mass, Electrospray Ionization, Bacteria (microorganisms), Listeria, Listeria monocytogenes, Posibacteria
Citation
Applied and Environmental Microbiology
68
11
68
11