Ammonia rhythm in Microcystis firma studied by in vivo 15N and 31P NMR spectroscopy

Cultures of the cyanobacterium Microcystis firma show rhythmic uptake and release of ammonia under conditions of carbon limitation. The massive removal of ammonia from the medium during the first light phase has little impact on the intracellular pH: a pH shift of less than 0.2 U towards the alkalin...

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Bibliographic Details
Published in:Archives of microbiology 1991-11, Vol.156 (6), p.471-476
Main Authors: Altenburger, R, Abarzua, S, Callies, R, Grimme, L.H, Mayer, A, Leibfritz, D
Format: Article
Language:English
Subjects:
amino acid metabolism
ammonia
assimilation
Bacteriology
Biological and medical sciences
carbon
carbon limitation
cation exchange
cell culture
cell walls
culture media
free amino acids
Fundamental and applied biological sciences. Psychology
mechanism of action
Metabolism. Enzymes
Microbiology
Microcystis
nitrates
nutrient sources
photoperiod
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Summary:Cultures of the cyanobacterium Microcystis firma show rhythmic uptake and release of ammonia under conditions of carbon limitation. The massive removal of ammonia from the medium during the first light phase has little impact on the intracellular pH: a pH shift of less than 0.2 U towards the alkaline can be measured by in vivo 31P NMR. Furthermore, the energy status of the cells remains regulated. In vivo 15N NMR of M. firma, cultivated either with labelled nitrate or ammonia as the sole nitrogen source, reveals only gradual differences in the pool of free amino acids. Additionally both cultivation types show gamma-aminobutyric acid, acid amides and yet unassigned secondary metabolites as nitrogen storing compounds. Investigating the incorporation of nitrogen under carbon limitation, however, only the amide nitrogen of glutamine is found permanently labelled in situ. While transamination reactions are blocked, nitrate reduction to ammonia can still proceed. Cation exchange processes in the cell wall are considered regarding the ammonia disappearance in the first phase, and the control of ammonia uptake is discussed with respect to the avoidance of intracellular toxification.
ISSN:0302-8933
1432-072X
DOI:10.1007/BF00245394