1887

Abstract

The effects of dilution rate and glucose, nitrogen or oxygen limitation on the intracellular and extracellular concentrations of adenine nucleotides, on the adenylate energy charge and on the specific activities of four enzymes of adenylate metabolism, have been investigated with chemostat cultures of . Under glucose limitation both ATP and ADP contents and the total adenylate pool increased with an increase in dilution rate while the energy charge remained constant at 0.85; the concentrations of extracellular ADP and AMP rose. With nitrogen limitation all the intracellular adenylates decreased with an increase in dilution rate while the concentration of extracellular ADP and AMP decreased markedly; the energy charge rose from 0.72 to 0.79. Under oxygen limitation the ATP content and total adenylate pool increased at higher dilution rates and the energy charge increased from 0.71 at = 0.1 h to 0.81 at = 0.15 h and then remained fairly constant; the concentration of extracellular adenylates decreased.

The specific activity of adenylate kinase was relatively unaffected by dilution rate under nitrogen or oxygen limitation but was inversely related to it in organisms grown under glucose limitation. AMP nucleosidase activity was inversely related to dilution rate under glucose-, nitrogen- and oxygen-limited conditions, while adenosine deaminase was relatively unaffected by dilution rate except for a decrease in organisms from oxygen-limited cultures at lower growth rates. The specific activity of adenine deaminase was inversely related to dilution rate in organisms grown under glucose and nitrogen limitation but showed little change under oxygen limitation. The principal route of AMP degradation in is mediated by AMP nucleosidase and adenine deaminase.

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/content/journal/micro/10.1099/00221287-125-2-375
1981-08-01
2019-12-08
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