Mechanism of Action of an Antibacterial Factor Derived from Bacillus subtilis FHC 402 on Salmonella typhimurium

The effects of Bacillus antibacterial factor (BAF) on oxygen uptake, transport systems, and macromolecular synthesis were studied in S. typhimurium. BAF had essentially no effect on oxygen uptake when glucose, succinate, lactate, α-ketoglutarate, pyruvate, and NADH served as substrates, suggesting that the respiration chain is not a target for BAF. The incorporation of [¹⁴C]leucine, [¹⁴C]acetate, and [¹⁴C]glucose into the washed cells was not inhibited by BAF, suggesting that BAF dose not affect these transport systems. The incorporation of [¹⁴C]leucine, [³H]uridine, and [³H]thymidine into the unwashed cells showed that BAF strongly inhibited protein synthesis, but not RNA and DNA synthesis. BAF also inhibited protein synthesis in a cell-free system from S. typhimurium. These results suggest that the primary site of antibacterial action of BAF is in the process of protein synthesis.