Studies on the biosynthesis of gramicidin S in whole cells of Bacillus brevis

Abstract

1. 1. When dl-[1- 14C]phenylalanine and dl-[5- 14C]ornithine respectively, were used, it was found that the synthesis of gramicidin S that occurred in whole cells of Bacillus brevis in the presence of chloramphenicol, and that was sufficient to prevent protein synthesis, represented synthesis de novo. 2. 2. The specific activity of gramicidin S in different cell fractions after brief labelling with dl-[1- 14C]phenylalanine was determined. Gramicidin S in the 105 000 × g fraction had by far the highest specific activity. 3. 3. Synthesis of gramicidin S de novo in the presence of chloramphenicol suggests a route of synthesis which differs from that of bacterial proteins. However, the high specific activity of gramicidin S in the 105 000 × g fractions suggests some relationship between the ribosomes and the synthesis of gramicidin S. 4. 4. Addition of mitomycin C (1 μg/ml) to a growing culture of B. brevis inhibited protein synthesis whereas gramicidin S synthesis continued with unchanged rate for another 2 h and therefore represents another instance in which the synthesis of gramicidin S continues in the absence of protein synthesis.