Influence of complex nutrients, temperature and pH on bacteriocin production by Lactobacillus sakei CCUG 42687

The effects of process conditions and growth kinetics on the production of the bacteriocin sakacin P by Lactobacillus sakei CCUG 42687 have been studied in pH-controlled fermentations. The fermentations could be divided into phases based on the growth kinetics, phase one being a short period of exponential growth, and three subsequent ones being phases of with decreasing specific growth rate. Sakacin P production was maximal at 20 °C. At higher temperatures (25–30 °C) the production ceased at lower cell masses, when less glucose was consumed, resulting in much lower sakacin P concentrations. With similar media and pH, the maximum sakacin P concentration at 20 °C was seven times higher than that at 30 °C. The growth rate increased with increasing concentrations of yeast extract, and the maximum concentration and specific production rate of sakacin P increased concomitantly. Increasing tryptone concentrations also had a positive influence upon sakacin P production, though the effect was significantly lower than that of yeast extract. The maximum sakacin P concentration obtained in this study was 20.5 mg l⁻¹. On the basis of the growth and production kinetics, possible metabolic regulation of bacteriocin synthesis is discussed, e.g. the effects of availability of essential amino acids, other nutrients, and energy. Received: 7 June 1999 / Received revision: 15 September 1999 / Accepted: 17 September 1999