Temperature- and surfactant-induced membrane modifications that alter Listeria monocytogenes nisin sensitivity by different mechanisms.
Nisin interacts with target membranes in four sequential steps: binding, insertion, aggregation, and pore formation. Alterations in membrane composition might influence any of these steps. We hypothesized that cold temperatures (10 degrees C) and surfactant (0.1% Tween 20) in the growth medium would influence Listeria monocytogenes membrane lipid composition, membrane fluidity, and, as a result, sensitivity to nisin. Compared to the membranes of cells grown at 30 degrees C, those of L. monocytogenes grown at 10 degrees C had increased amounts of shorter, branched-chain fatty acids, increased fluidity (as measured by fluorescence anisotropy), and increased nisin sensitivity. When 0.1% Tween 20 was included in the medium and the cells were cultured at 30 degrees C, there were complex changes in lipid composition. They did not influence membrane fluidity but nonetheless increased nisin sensitivity. Further investigation found that these cells had an increased ability to bind radioactively labeled nisin. This suggests that the modification of the surfactant-adapted cell membrane increased nisin sensitivity at the binding step and demonstrates that each of the four steps can contribute to nisin sensitivity.
Li
Jie
J
Department of Food Science, Cook College, The New Jersey Agricultural Experiment Station, Rutgers, The State University of New Jersey, New Brunswick 08901, USA.
Chikindas
Michael L
ML
Ludescher
Richard D
RD
Montville
Thomas J
TJ
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005227:Fatty Acids / Q000032:analysis; D008089:Listeria monocytogenes / Q000187:drug effects*; D008560:Membrane Fluidity / Q000187:drug effects; D009561:Nisin / Q000494:pharmacology*; D013501:Surface-Active Agents / Q000494:pharmacology*; D013696:Temperature
D000900:Anti-Bacterial Agents; D005227:Fatty Acids; D013501:Surface-Active Agents; D009561:Nisin