Abstract
The terrestrial cyanobacterium Nostoc commune is highly desiccation-tolerant and has a cosmopolitan distribution. The desiccation tolerance of photosynthesis and the role of extracellular polysaccharides for that tolerance in N. commune were studied. The activity of oxygen evolution was not detected from a desiccated sample, and was rapidly recovered with rehydration. The air-dried N. commune was treated with dry oven at 80C and approximately 10% of water was removed from the air-dried N. commune. The oxygen evolving activity was still remained approximately 60% after the desiccation treatment. N. commune colonies were homogenized and filtered with a coarse paper filter to separate the cells from extracellular polysaccharides. This treatment did not ruin the oxygen evolving activity, but the activity was severely damaged after desiccation in the cells. This result suggests that extracellular polysaccharides have an important role for the desiccation tolerance in N. commune.
