Antagonism between basic compounds (spermine, streptomycin) and basic bactericidal substances

THE following bactericidal substances—trypaflavine (5 × 10-4 M), methylene blue (1 × 10-3 M), protamine sulphate (2.5 × 10-4 M), chinine (2·5 × 10-3 M) and crystal violet (1 × 10-4 M)—cause a strong and progressive inhibition of the respiration of bakers' yeast, suspended in glucose phosphate at 28° C. (cf. also ref. 1). Spermine and streptomycin, though also basic substances, even at high concentrations (1 × 10-2 M and 1 × 10-2 M respectively) do not affect the respiration of yeast and thus have no direct bactericidal activity. It can be shown that all these substances, the inhibitors as well as spermine and streptomycine, compete for the same negative components of the yeast cell, when brought in contact with a yeast suspension2.