SUMMARY: The effect of dissolved oxygen concentration on glucose metabolism, poly-β-hydroxybutyr-ate (PHB) synthesis and respiration of nitrogen-fixing was investigated over a range of values spanning oxygen limitation and sufficiency (nitrogen limitation) in continuous culture. The activities of the Entner-Doudoroff enzymes decreased with increasing oxygen supply while glucose-6-phosphate dehydrogenase was unaffected; β-ketothiolase and acetoacetyl-CoA reductase decreased more markedly, reflecting the fall in PHB content. The metabolic quotients for O and CO increased rapidly with increasing oxygen supply, in keeping with the respiratory protection of nitrogenase. The specific activities of all these enzymes, and also of fructose-1,6-bisphosphate aldolase, increased with increasing dilution rate under either oxygen or nitrogen limitation, except that both β-ketothiolase and acetoacetyl-CoA reductase activities fell at the highest dilution rate (0·23 h) under oxygen limitation. It was concluded that the role of the Entner-Doudoroff sequence as the major route of glucose metabolism in was unaffected by oxygen concentration and growth rate.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error