In order to investigate factors influencing the production of the bacteriocin, sakacin P, Lactobacillus sakei CCUG 42687 was grown in a completely defined medium (DML-B) with 33 components. Although the maximum sakacin P concentration obtained was higher on a complex medium due to higher cell mass, the production per cell mass was higher in DML-B. Sakacin P was produced at 4-30 degrees C, with the highest specific production at low temperatures. More sakacin P was produced at uncontrolled pH compared with cultivation at pH 6.3. Tween-80 had a positive effect on sakacin P production, while addition of sodium chloride and trace metals had negative effects. The decrease in sakacin P concentration during the late growth and stationary phases was shown to be cell-independent and promoted at high temperature and pH. Some differences in production levels of sakacin P were found among six strains of Lactobacillus sakei tested.