Alternative function of the electron transport system in Azotobacter vinelandii: removal of excess reductant by the cytochrome d pathway

The N2-fixing bacterium Azotobacter vinelandii was grown in an O2-regulated chemostat with glucose or galactose as substrate. Increasing the O2 partial pressure resulted in identical synthesis of the noncoupled cytochrome d terminal oxidase, which is consistent with the hypothesis that A. vinelandii...

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Bibliographic Details
Published in:Applied and Environmental Microbiology 1995-11, Vol.61 (11), p.3998-4003
Main Authors: Liu, J.K. (National Sun Yet-Sen University, Taiwan, ROC.), Lee, F.T, Lin, C.S, Yao, X.T, Davenport, J.W, Wong, T.Y
Format: Article
Language:English
Subjects:
ABSORCION DE SUSTANCIAS NUTRITIVAS
ABSORPTION DE SUBSTANCES NUTRITIVES
AZOTOBACTER VINELANDII
Biological and medical sciences
Biology of microorganisms of confirmed or potential industrial interest
Biotechnology
CADENA RESPIRATORIA
CHAINE RESPIRATOIRE
CITOCROMOS
CYTOCHROME
Fundamental and applied biological sciences. Psychology
GALACTOSA
GALACTOSE
GLICOLISIS
GLUCOSA
GLUCOSE
GLYCOLYSE
METABOLISME DES GLUCIDES
METABOLISMO DE CARBOHIDRATOS
Mission oriented research
OXIDORREDUCTASAS
OXIGENO
OXIRREDUCION
OXYDOREDUCTASE
OXYDOREDUCTION
OXYGENE
Physiology and metabolism
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Summary:The N2-fixing bacterium Azotobacter vinelandii was grown in an O2-regulated chemostat with glucose or galactose as substrate. Increasing the O2 partial pressure resulted in identical synthesis of the noncoupled cytochrome d terminal oxidase, which is consistent with the hypothesis that A. vinelandii uses high rates of respiration to protect the nitrogenase from oxygen. However, cell growth on glucose showed a lower yield of biomass, higher glycolytic rate, higher respiratory rate, and lower cytochrome o content than cell growth on galactose. Elemental analysis indicated no appreciable change in the C-to-N ratio of cell cultures, suggesting that the major composition of the cell was not influenced by the carbon source. A poor coordination of glucose and nitrogen metabolisms in A. vinelandii was suggested. The rapid hydrolysis of glucose resulted in carbonaceous accumulation in cells. Thus, Azotobacter species must induce a futile electron transport to protect cells from the high rates of glucose uptake and glycolysis
ISSN:0099-2240
1098-5336
DOI:10.1128/AEM.61.11.3998-4003.1995