Figure 5.26Ammonia incorporation in bacteria. To follow the flow of nitrogen, both free ammonia and the amino groups of all amino acids are shown in blue. Two major pathways for NH3 assimilation in bacteria are those catalyzed by the enzymes (a) glutamate dehydrogenase and (b) glutamine synthetase. (c) Transaminase reactions transfer an amino group from an amino acid to an organic acid. (d) The exzyme glutamate synthase froms two glutamates from one glutamine and one alpha-ketoglutarate