Comparative Studies on the Metabolism of Lactose, Glucose and Galactose in Liquid Cultures of E. coli

Abstract

WE have carried out comparative investigations concerning the metabolism of lactose and its constituent monoses in liquid cultures of E. coli. Koser's synthetic medium was used. Samples were evaluated after incubation of 0, 6, 12, 24, 48, 72 and 96 hr. at 37° C, for increase of bacterial mass (nephelometrically), pH, and changes in the medium concerning the reducing compounds. In the chromatographic technique we used, as solvents, butanol–pyridine–water in the proportion of 45 : 25 : 40. To reveal the spots of reducing compounds, a modified silver nitrate test was used. The intensity and size of the spots developed were a measure of the concentration of the substrates in the medium.