
Full text loading...
SUMMARY: When Aerobacter aerogenes was harvested from citrate + mineral salt media in which the concentration of carbon source limited the crop, citridesmolase activity of cells was high but was absent when growth ceased with citrate in excess. These differences were abolished by disintegration of the cells. The ability of Escherichia coli to dissimilate citrate was measurable only after growth in a medium containing peptone, citrate and glucose: when the latter was consumed activity fell and was revived by further glucose additions. Differences in activity of such cells were not abolished by their disintegration. Cells lost their activity when incubated for 30 min. with phosphate buffer or with the citrate + mineral salt medium that supports growth of A. aerogenes. E. coli grown at the expense of glucose in a mineral salt medium + citrate, did not utilize citrate for growth during the first day and no citridesmolase activity could be detected, but when subsequently tested in a medium which permitted development of activity, higher activities were reached by cells that had grown in presence of citrate. E. coli grown in peptone + citrate + glucose medium possessed little oxaloacetate decarboxylase; by the action of disintegrated cells, citrate gave rise to equimolar quantities of keto-acid, chiefly oxaloacetic acid.