Peptide antibiotics and sporulation: induction of sporulation in asporogenous and peptide-negative mutants of Bacillus brevis.

Mutants of Bacillus brevis ATCC 8185 were isolated which were unable to produce detectable amounts of either tyrocidine or linear gramicidin, or both peptide antibiotics. Tyrocidine-negative mutants (BM5, BM21, BM44) sporulated normally. Gramicidin-negative mutants (BM2, BM24) were oligosporogenous, and mutants unable to produce both peptides (S18, S19) were asporogenous.

Induction of sporulation in Bacillus brevis. 2. Dependence on the presence of the peptide antibiotics tyrocidine and linear gramicidin.

This paper presents evidence that the two peptide antibiotics tyrocidine and linear gramicidin, produced by Bacillus brevis ATCC 8185, are required for the induction of sporulation in the producer organism. When tyrocidine synthesis was specifically blocked with 2-amino-3-hydroxy-3-phenylpropanoic acid [Mach, B., Reich, E.

Functions of the peptide antibiotics tyrocidine and gramicidin. Induction of conformational and structural changes of superhelical DNA.

The peptide antibiotic tyrocidine which is produced by Bacillus brevis and is probably involved in sporogenesis, unwinds superhelical plasmids in vitro at low peptide: DNA ratios, as found by gel electrophoresis. At higher peptide concentrations, the DNA is packed tightly leading to apparent nuclease stability of the complex and inhibition of RNA synthesis. The addition of the linear gramicidin, another peptide antibiotic synthesized by the same bacterial strain, partially restores transcription by breaking down the tightly packed DNA X peptide complex.