FORMATION AND RELEASE OF LECITHINASE ACTIVITY BY GROWING CULTURES OF BACILLUS CEREUS

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Abstract
Bacillus cereus growing in complex media (nutrient broth, "S" broth, and enzymically hydrolyzed casein) formed lecithinase only after the logarithmic growth phase. About one-third of this activity was cell-bound. In a synthetic amino acid mixture, lecithinase was formed during the logarithmic growth phase. The later appearance of activity in complex media does not appear due to enzyme instability, to the absence of amino acids, nor to the presence of an inhibitor; it may be related to the higher growth rate. The addition of egg yolk (but not purified lecithin) to growth media increased lecithinase formation fourfold.Although cells in a bacterial culture had lecithinase activity, cells removed from the culture were inactive. Following growth, the culture medium contained dialyzable material essential for the activity of the cell-bound, though probably not of the cell-free, lecithinase. A delay in activator production may have caused the delay in lecithinase appearance in complex media. The inhibitory effect of alcohols on the formation of lecithinase activity seems primarily due to their effect on activator production. It is suggested that activating material may be involved in the transition of the enzyme from the cell-bound to the cell-free state.