Abstract
The ability of L. monocytogenes cells to adapt to a variety of stressors contributes to its growth in a wide range of foods. The present study examines the effect of acid and of the acid tolerance response (ATR) on membrane fluidity and on the organism's resistance to acid and to the bacteriocin nisin. When ATR was induced in wild-type cells, these cells also became resistant to nisin. ATR(+) cells also had lower membrane rigidities than control ATR(-) cells that had not been subjected to the acid tolerance response. However, cells that were genetically resistant to nisin did not show any significant (P < 0.05) change in rigidity when grown in the presence of nisin. These studies suggest that the use of acid and nisin for L. monocytogenes control in ready-to-eat foods may be compromised if cross-resistance emerges.