BACTERICIDAL EFFECT OF ADP AND ACETIC-ACID ON BACILLUS-SUBTILIS

Bacillus subtilis is a ubiquitous soil bacterium used for measuring th e beta-lysin activity and in other bioassays, We observed a complete b actericidal effect of ADP on B. subtilis at concentrations of 50-100 m u M at pH values <5.5, which disappeared at pH values above 6, The eff ect was also found for acetic acid at concentrations >17.4 mu M and si milar pH values, ATP, adenosine, and HCl were not bactericidal, We use d BCECF-AM, a pH-sensitive probe, and found that the killing of B. sub tilis was due to a change in the intracellular pH caused by the passag e across the cell membrane of these weak organic acids when incubated with B. subtilis at pH values near the pK. More experiments are needed to determine the biological meaning of these in vitro findings.