Studies on the Role of Calcium Ions in Acetylene Reduction (Nitrogen Fixation) by <i>Gloeocapsa</i> sp. 1430/3

Hamadi, Ahmad; Gallon, John

doi:10.1042/bst0071266

Cited by 4 publications

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“…In the dark, the catabolism of storage glucan is the only potential source of ATP and/or reductant for N, fixation, or, indeed, for any other metabolic process. Gloeocapsa reduces acetylene in the dark anaerobically at a rate which is comparabie to that found aerobically (Hamadi & Gallon, 1979). This suggests that substrate level phosphorylation might play an important role in N, fixation by Gloeocapsa in the dark.…”

Section: Results a N D Discussionmentioning

confidence: 58%

Effects of a Light to Dark Transition on Carbon Reserves, Nitrogen Fixation and ATP Concentrations in Cultures of Gloeocapsa (Gloeothece) sp. 1430/3

1980

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Between 30 s and 5 min after transfer from light to darkness, the rate of acetylene reduction by cultures of the unicellular cyanobacterium Gfoeocapsa sp. 1430/3 decreased rapidly. During the same period, there was a rapid disappearance of storage glucan. There was also a sharp fall in the intracellular concentration of ATP followed by a slower recovery. It is concluded that, in the dark, the catabolism of storage glucan is the only potential source of ATP and/or reductant and that the low rate of Nz fixation in the dark is not due to limitations in the supply of ATP. METHODS Growth of cultures. Clueocupsa sp. CCAP 1430/3 (Culture Centre of Algae and Protozoa, Cambridge) was grown in 15 I of sterile medium free of combined nitrogen (Gallon et ul., 1978) or in the same medium with NaCl replaced by 2 mM-NH,CI. The latter cultures were maintained at pH 7.6 during growth by the addition of sterile NaOH solution. Six days after inoculation, the cells were allowed to settle under gravity for approximately 4 h, and the

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Section: Results a N D Discussionmentioning

confidence: 58%