Abstract
Ice algal species could grow under the sea ice and maintain the photosynthetic rates at the temperature just above the freezing point of seawater. Isolated strain of ice algae Detonula Confervacea (Cleve) Gran could grow at -5oC in the supercooled seawater, although it could not at -7.5oC without freezing. Temperature conditions under the sea ice would be the lowest for the photosynthesis, as most of the reactions in the photosynthetic system need the liquid water for their activities. The activity of the key enzyme of photosynthesis, RuBisCO, was also essential for the photosynthesis at low temperature. Primary structures of RuBisCO were determined with many ice algal species and common structures indispensable for the activity at low temperature were estimated.
