[Enzymes of ammonia assimilation in bacteria with different C1-metabolic pathways]

The object of this work was to study enzymes involved in ammonium assimilation by 15 bacterial strains of different taxonomy. The bacteria utilizing methanol and methylated amines as the sources of carbon and energy have one of the three cyclic pathways of C1-metabolism: the serine pathway, the hexulose phosphate pathway or the ribulose diphosphate pathway. The bacteria were found to differ in the enzymes for ammonium assimilation according to the pathways of primary C1-metabolism. The bacteria with the serine cycle were characterized by the reductive amination of pyruvate and the operation of the glutamate cycle (glutamine synthetases and glutamate synthases). The reductive amination of alpha-ketoglutarate is the principal pathway of ammonium nitrogen assimilation in the bacteria with the hexulose phosphate cycle. The bacteria using reduced C1-substrates autotrophically, i.e. via the ribulose diphosphate pathway, have the enzymes of the glutamate cycle, but are characterized by low activities, if any, of amino acid dehydrogenases.