Lethal action of ribonuclease for thermophilic bacilli

Thompson, T. L. (University of Nebraska, Lincoln), and J. M. Shively. Lethal action of ribonuclease for thermophilic bacilli. J. Bacteriol 91:673-676. 1966.-Exposure of a thermophilic bacillus, NU 47, to 0.2 mug/ml of pancreatic ribonuclease resulted in a drastic reduction of viable cells. The observed lethality is thought to be associated specifically with the ribonuclease, since heat treatment did not diminish activity and the addition of ribonucleic acid to the cells completely eliminated the action of the enzyme. Cells from 2-hr cultures, buffered between pH 6.0 and 7.0, were most sensitive. The lethal action was most pronounced when cells were exposed to the enzyme at temperatures between 25 and 45 C. A greater proportion of cells survived at higher temperatures. The release of ultraviolet-absorbing materials into the medium after exposure to enzyme could not be detected.