Utilization of amino acids by Bacillus subtilis during growth and antibiotic production

Abstract

Studies on the utilization of fifteen amino acids from a casein hydrolyzate-beef extract-dextrose medium indicate that all these amino acids, which disappear either partially or completely during the production of an antifungal antibiotic by Bacillus subtilis, appear as free or combined amino acids of the cells. The combined amino acid composition of these cells remains partially constant over the entire period while their accumulated free amino acids record a rapid fall in concentration between 72–96 h, when rapid antibiotic formation, but practically no cell synthesis, occurs. The disappearance of these free amino acids without the consequent cell synthesis or reappearance in the broth indicates that these free acids, particularly glutamic acid, leucine, alanine, threonine, serine, aspartic acid, tyrosine, valine and leucines may be involved in the biosynthesis of the antibiotic molecule.