Effect of Nutrients Upon Growth of Streptomycin-Sensitive,-Resistant-and -Dependent Strains of Escherichia coli. ∗ †

Abstract

Summary

1. Growth of a streptomycin-dependent strain of E. coli in nutrient broth was favored by the presence of sodium chloride.

2. Glucose, pyruvate, and fumarate, when added to nutrient broth minus sodium chloride, caused greater growth of the streptomycin-dependent strain. With nutrient broth alone and nutrient broth plus glucose, the greatest initial growth took place in the presence of 5 μg streptomycin/ml. Nutrient broth plus the sodium salts of pyruvate and fumarate, however, favored a greater initial growth in higher concentrations of streptomycin (25 μxg/ml).

3. In a synthetic medium containing glucose, pyruvate and fumarate as carbon sources, the growth of the sensitive parent E. coli strain was inhibited by 5 μg/ml; the dependent strain grew in all concentrations of streptomycin from 5 to 1000 μ/ml, but not in media without streptomycin. One resistant strain grew in all concentrations of streptomycin as well as in media without streptomycin, while a second resistant strain grew only in a streptomycin concentration of 500 μg/ml with pyruvate and fumarate as carbon sources.

4. This second streptomycin resistant strain was transformed into a streptomycin-dependent strain under the above conditions. The dependent strain so obtained remained dependent after several transfers on nutrient agar containing streptomycin, and in turn gave rise to streptomycin-sensitive cells when a large inoculum was placed in streptomycinfree nutrient broth.