A Study of Adaptation in Azotobacter
1954
Harris, John O.
The age of cells was shown to be an important factor in the rate at which Azotobacter chroococcum adapts its respiratory mechanism to the utilization of different substrates. These organisms are able to utilize dilute (M/400) solutions of glucose or mannitol for respiration. Experiments measuring oxygen uptake and dehydrogenase activity of intact cells indicated that simultaneous oxidation of two substrates is possible by partially adapted cells. Studies of enzymatically active cell-free extracts showed that the Kreb's cycle of terminal oxidation probably occurs in Azotobacter chroococcum. Glucose and mannitol dehydrogenases appeared to be formed only when these compounds were present. This was interpreted as evidence that at least part of the adaptation process is due to formation of new enzyme systems.
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