Relationship between exoprotease secretion and the synthesis of ribonucleic acid and protein in Bacillus amyloliquefaciens.

Studies with washed bacteria suspended in fresh medium, in which bacterial densities were altered by a factor of four so as to cause accelerated entry of exponential bacteria into the postexponential phase and to re-establish growth in postexponential bacteria, have been performed. Under all the conditions examined rifampin, at a concentration of 0.5 mug/ml, inhibited [(14)C]uracil incorporation into total ribonucleic acid (RNA) by 90 to 95%. The percentage of inhibition of incorporation of (14)C-labeled amino acids into total protein achieved in parallel experiments was less, being not more than 80%. These results suggested that non-translatable RNA synthesis was inhibited more than messenger RNA (mRNA) by the antibiotic. It was found that on slowing the growth of exponential-phase bacteria exoprotease was formed at a high rate without a lag. It was further observed that when postexponential bacteria were induced to grow, by resuspending them at a lower density, exoprotease mRNA synthesis was switched off. The only synthesis of exoprotease which occurred in this case was accountable to pre-existing mRNA during its decay. Exoenzyme formation was found to be less susceptible to rifampin than total protein synthesis.