EXTRACELLULAR RIBONUCLEASE FORMATION IN BACILLUS SUBTILIS AND ITS STIMULATION BY ACTINOMYCIN D

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Abstract
Extracellular ribonuclease is produced linearly for at least 3 hr. by washed post-logarithmic-phase cells of B. subtilis suspended in a medium containing maltose (1%) and casein hydrolysate (0.5%). Low concentrations of actinomycin-D (less than 2 [mu]g/ml) stimulate ribonuclease formation, the maximum effect with a concentration of 1 [mu]g/ml. Concentrations greater than 2 [mu]g/ml are inhibitory. There is no parallel stimulation of a -amylase formed under the same conditions, and [C14] uracil incorporation into a perchloric acid-insoluble form is inhibited. The actino-mycin-D-induced stimulation is not due to the presence of an activator, and the inhibition is not due to the release of an inhibitor by the cells. The amount of ribonuclease produced in the medium is affected. Extracellular ribonuclease formation is partially inhibited by anaerobiosis, 2,4-dinitrophenol, sodium azide chloramphenicol and puromycin. High concentrations of antibiotic do not completely inhibit ribonuclease formation, but a basal amount of enzyme representing 20min. synthesis in an uninhibited system is always produced. This "antibiotic-insensitive" enzyme may represent performed enzyme before secretion. The stimulated appearance of ribonuclease in the presence of 1 [mu]g of actinomycin-D/ml depends on enzyme synthesis. The mechanism is discussed.