Studies on bacterial cell wall inhibitors. VIII. Mode of action of a new antibiotic, azureomycin B, in Bacillus cereus T.

Azureomycin B, a new antibiotic which contains sugar, amino acid and phenol moieties and inhibits Gram-positive bacteria, was found to be a specific inhibitor of peptidoglycan synthesis in bacteria. The antibiotic lysed growing cells of Bacillus cereus T at a concentration of 10 micrograms/ml but did not affect resting cells. Microscopical observation revealed swelling and lysis of the bacterial rods when treated with azureomycin B. The incorporation of [3H]diaminopimelic acid or [14C]glucosamine into acid-insoluble fraction of growing cells of Bacillus cereus T was strongly inhibited in the presence of azureomycin B, but that of [14C]leucine, [3H]thymidine or [3H]uridine were not, at least until 5 minutes after the beginning of the incubation. The antibiotic caused accumulation of a nucleotide precursor in the cells which was identified as UDP-MurNAc-L-Ala-D-Glu-meso-Dpm-D-Ala-D-Ala. Thus the site of action was suggested to lie between this nucleotide and peptidoglycan in the pathway of peptidoglycan synthesis.