Uptake of 14C-streptomycin by some Micro-organisms and its Relation to their Streptomycin Sensitivity

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Abstract
The uptake of radioactivity from 14C -streptomycin in a form which cannot be displaced from the organisms by unlabelled streptomycin was determined in several species of bacteria and one yeast growing under standard conditions. This uptake showed a good correlation with the sensitivity of the organism to streptomycin and in streptomycin-resistant organisms was about 1% of that in a highly sensitive organism Bacillus megaterium. The quantity of streptomycin taken up when growth ceased represented an intracellular concentration 10- to 50-fold higher than that in the growth medium. Environmental factors such as anaero-biosis or presence of carbon monoxide which increased the resistance of Staphylococcus aureus to streptomycin also resulted in decreased rates of uptake of 14C-streptomycin. When Bacillus subtilis grew in medium containing the streptomycin antagonist 2-n-heptyl-4-hydroxy-quinoline N-oxide, the rate of uptake of radioactivity was reduced to about 30% of that in absence of the antagonist; the rate at which harvested organisms oxidized succinate and malate was reduced to a similar extent.