In vitro production of bacitracin by proteolysis of vegetative Bacillus licheniformis cell protein

Abstract

The action of a sporulation-specific seryl protease on antibiotic-free extracts of B. licheniformis cells yields a peptide that is identified as bacitracin by its biological activity, its spectral properties, and its comigration with genuine bacitracin in both paper and thin-layer chromatography. During proteolysis, a chemical structure is generated with the spectral properties of a Δ-2 thiazoline ring. The yield in vitro, 4 μg of bacitracin per mg of protein, is less than the maximal yield from sporulating cells, 75 μg of bacitracin per ng of cell protein, but is a linear function of the amount of protein in the reaction system. Approximately 30% of the protein yielding the antibiotic is ribosomal associated, and only 25% of that amount can be removed by washing with 1 M NH4Cl. The substrate protein is a constant fraction of the cell protein throughout exponential growth and very early sporulation stages of culture development.