[Amination in E. coli strains effectively producing threonine]

The effect of the mutation of threonine and homoserine resistance (thrr) on the activity of the enzymes catalysing the biosynthesis of glutamic acid, glutamate synthase (EC 1.4.1.13) and glutamate dehydrogenase (EC 1.4.1.4), and on the productivity of a threonine-producing E. coli strain obtained by gene engineering was being studied. The resistance to threonine was found to correlate well with the increasing activities of the abovementioned enzymes and with a higher productivity of the E. coli strain.