Abstract
Minimal inhibitory concentrations of penicillin and of streptomycin sulphate have been determined for certain species of Lactobacillus, Streptococcus and Acetobacter. Lactobacilli and streptococci are in general sensitive to low concentrations of penicillin, but species of Acetobacter are more resistant to this. All lactic bacteria tested resisted streptomycin sulphate at 20 μg. per ml., a concentration which inhibited most of the species of Acetobacter tested; however, resistance by Acetobacter to streptomycin is greatest in cellulose-producing species.