Combined effect of NaCl and low temperature on antilisterial bacteriocin production of Lactobacillus plantarum ST202Ch

The aim of our study was to examine the combined effect of NaCl and low temperature on antilisterial bacteriocin production of L. plantarum. Traditionally, the activity of the bacteriocin (arbitrary unit/ml) is determined as an adaptation of the critical dilution method. With that methodology, the value of AU/ml is a discrete variable, which may cause information loss. Therefore, redox potential measurement technique was applied. Bacteriocin producer L. plantarum and a bacteriocin sensitive L. monocytogenes strain were selected for this study. The measure of the inhibition activity of bacteriocin was expressed in ΔTTD terms which means the difference between the detection times of L. monocytogenes in inhibited and non-inhibited culture media. During the L. plantarum fermentations the antilisterial activity proved to be the highest in the transient section between the late linear and stationer phase of the logarithmic growth curves. Multiple regression model was established to describe the combined effect of temperature and NaCl concentration on the bacteriocin production of L. plantarum.