Production of Cell‐Bound Proteinase by Lactobacillus bulgaricus and its Location in the Bacterial Cell

Lactobacillus bulgaricus NCDO 1489 produced a single, cell‐bound proteinase during growth on nutrient medium at 45°C. Proteinase activity was optimal at 45–50°C and pH 5.2–5.8. and was inhibited by chelating agents. The enzyme was mainly associated with the cell envelope but could be liberated from cells under conditions favouring autolysis or by treatment of the cells with lysozyme. Its relation to the growth of the organism in milk and possible role in formation of fermented milk products are discussed.