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

Abstract

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.