| Abstract: | Methanobacterium thermoautotrophicum can utilize glutamine and urea as well as ammonia as the sole nitrogen source during growth on H2 and CO2. High-field 15N-NMR has been used to compare the assimilation of these different nitrogen sources by this organism. The 15N-NMR spectra of extracts of cells grown in media containing delta-15N]glutamine as the nitrogen source show that the glutamine amide nitrogen is rapidly converted to glutamate. The 15N-NMR spectra of cell extracts from cells grown on 15N]urea show a marked increase in the labeling of the alpha-NH2 of glutamate concurrent with a decrease in the urea resonance. These two nitrogen sources do not show the metabolic shift to alanine as the major resonance in stationary phase as is seen with 15NH4Cl. This behavior is discussed in terms of the enzymes of nitrogen metabolism. |
