Fructose supports glycogen accumulation, heterocysts differentiation, N2fixation and growth of the isolated cyanobiontAnabaena azollae
✍ Scribed by Anat Rozen; Hanna Arad; Mordechay Schönfeld; Elisha Tel-Or
- Publisher
- Springer
- Year
- 1986
- Tongue
- English
- Weight
- 420 KB
- Volume
- 145
- Category
- Article
- ISSN
- 0302-8933
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✦ Synopsis
Cells of the cyanobiont Anabaena azollae isolated from the water fern Azollafiliculoides were found to take up and utilize fructose in the light for mixotrophic growth. Fructose was favored by the cyanobiont as a substrate over sucrose and glucose. Cell growth in the presence of 8 mM fructose led to glycogen accumulation in the cells which approached 20% of the cell dry weight within 2 to 3 days, followed by reduction of glycogen content during the fourth day. Glucose-6-phosphate dehydrogenase activity was increased 5-6-fold in the fructose grown cells from the third day of growth onwards. The frequency of heterocysts in fructose-grown cells increased from 6 to 18%, and acetylene reduction by nitrogenase was increased 3-fold in the presence of fructose as compared with control cells, with maximum values observed between the third and fifth day of mixotrophic growth. Fructose-supported growth yielded a 2-4-fold increase in cell dry weight over controls.
It is suggested that fructose-supported development and growth of the cyanobiont in batch cultures may resemble its mixotrophic growth and development in situ in the leaf cavity of the host fern Azolla.