Effects of the peptide antibiotics tyrocidine and the linear gramicidin on RNA synthesis and sporulation of Bacillus brevis

Abstract

Effects of the two peptide antibiotics tyrocidine and the linear gramicidin on exponential growing cultures of Bacillus brevis (ATCC 8185) were studied. Both antibiotics are produced by this bacterial strain. Our results demonstrate that the addition of tyrocidine leads to inhibition of RNA synthesis followed by a cessation of growth. In contrast, gramicidin does not affect net RNA synthesis and the cells continue to grow. However, sporulation is inhibited by gramicidin. The addition of a mixture of tyrocidine and gramicidin prevents partially the inhibitory effect of tyrocidine on RNA synthesis. The results presented are essentially in agreement with in vitro results described previously (8,9).