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Title: The effect of environmental factors on nitrogen fixation by Gloeocapsa
Author: Mullineaux, P. M.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1982
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When illuminated cultures of Gloeocapsa CCAP sp. 1430/3 were transferred to darkness there was an initial fall in the rate of acetylene reduction (N₂ fixation), which may have been caused by a decrease in the rate of reduction of ferredoxin and/or a decrease in the rate of synthesis of carbon skeletons required for the assimilation of newly fixed N₂. Upon longer incubation in the dark, the synthesis and activity of nitrogenase continued for 4 h. After this period, there was a dramatic inhibition of nitrogenase synthesis, which when coupled with the irreversible inactivation of the enzyme by atmospheric oxygen caused a further dramatic decline in nitrogenase activity. The inhibition of nitrogenase synthesis in dark-incubated cultures may have been caused by an associated rise in the endogenous amino acids pools. Growth of cultures under a light-dark cycle resulted in most of the nitrogenase activity occurring during the dark phase, and may have been a means of temporally separating nitrogenase activity from photosynthesis. The pattern of dark nitrogenase activity in cultures grown under natural cycles of light and dark may have some ecological significance.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available