Influence of lysozyme on selected bacteria associated with gouda cheese

Abstract

The germination of Clostridium tyrobutyricum spores; the growth of vegetative cells of C. tyrobutyricum; and the growth of four cultures each of lactobacilli, coliform bacteria, and cheese starter cultures were studied in culture media containing various levels of lysozyme. Lysozyme was found to inhibit vegetative growth of both isolates (BZ15 and C611) of C. tyrobutyricum at concentrations equal to and greater than 250 units/ml. Spore germination was stimulated by lysozyme with maximum stimulation at 250 units/ml. This effect was more evident with the slower germinating strain, C611. One Lactobacillus isolate was not affected by lysozyme while the other three isolates were inhibited by 500 to 1000 units/ml of lysozyme, but were not affected by lower concentrations. The activity of the four starter cultures was not affected by lysozyme concentrations of up to 2500 units/ml. Growth of three coliform isolates was inhibited by 1000 units/ml of lysozyme, but was not significantly affected by lower concentrations of the enzyme. Growth of the fourth coliform isolate was stimulated by lysozyme at all the concentrations used in the experiments.