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Abstract
Summary: Anabaena variabilis (ATCC 29413) grown in batch cultures for 2 d exhibited rapid glycogen synthesis upon dilution of the cell suspension. The cellular polysaccharide concentration attained a maximum after 9-12 h growth in fresh medium and decreased thereafter. The growth rate, the rate of glycogen accumulation and the maximum amount of glycogen increased when light intensity was increased. Accumulation occurred with both N2 and ammonia as N-sources. In cultures grown in the presence of ammonia, the increase in the cellular C-fraction upon dilution caused neither induction of nitrogenase nor heterocyst formation. However, ammonia depletion during subsequent growth gave rise to a second accumulation of glycogen followed by differentiation. Thus, in this phototroph, glycogen is synthesized without subsequent differentiation following an increase in average irradiation as long as the N-supply is maintained. Glycogen synthesis following N-depletion, however, is accompanied by induction of nitrogenase.
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