Tant of E. coli growing under ammonium-limited conditions accumulated glutamine (12 mM) relative to the wild type (2 mM) (135). Induction of AmtB from a plasmid by IPTG (in order to increase the intracellular ammonium concentration so that GDH would be active) did not have the anticipated positive effect on growth of the gltB mutant, however (281). (v) The glnHPQ operon. E. coli can use glutamine