Microbiological Studies of Coli-aerogenes Bacteria

Part IX. On the Mechanism of Assimilation of Ammonia

Abstract

1) The activity of aspartase, a combined re-saction of aspartase and aspartic-glutamic trans-aminase, and a coupling reaction between isocitric dehydrogenase and glutamic dehydro-genase were investigated with the bacterial cells or cell extracts of coli-aerogenes obtained under various conditions. The growth-media tested were such as bouillon-, citrat- bouillon-and glucose-ammonium nitrogen-media.
2) In all of the cases tested aspartase activity was observed to be extremely high.
3) It was ascertained that the combined re-action of aspartase and aspartic-glutamic trans-aminase by the cell extracts of the bacteria proceeded at an exceedingly high rate, whereas, a coupling reaction between isocitric dehy-drogenase and glutamic dehydrogenase by the disrupted cells or the fresh cell extracts occurred at an exceedingly low rate.
4) It was found that isocitritase was operative even under such the conditions that the fresh cell extracts were incubated in the presence of addition of citrate and ammonium ion.
5) The addition of coenzyme triphosphopy-ridine nucleotide to a mixture containing the fresh cell extract brought about an increase in the yield of glutamate or α-ketoglutarate.
6) The mechanism of assimilation of ammonia in the bacteria was discussed.