THE MODE OF ACTION OF NANAOMYCIN A IN GRAM-POSITIVE BACTERIA

The mode of action of nanaomycin A on Gram-positive bacteria such as Staphylococcus aureus, Bacillus cereus and Streptococcus faecalis was investigated. Nanaomycin A inhibited the biosyntheses of protein, DNA, RNA and cell-wall peptidoglycan to a similar extent. It increased the exogenous respiration of S. aureus cells at the minimal inhibitory concentration. The cells preincubated with nanaomycin A showed stimulation of proton influx after addition of N, N'-dicyclo-hexylcarbodiimide, an inhibitor of Ca++ Mg++-ATPase. Nanaomycin A seems to interfere with the cytoplasmic membrane or to inhibit coupling of oxidative phosphorylation, followed by secondary inhibitory effect on protein, nucleic acids and cell-wall peptidoglycan biosyntheses.