Effect of Ammonia and Nitrate on Growth, Photosynthesis, and Ribulosediphosphate Carboxylase Content of Dunaliella tertiolecta



When the marine Chlorophycean flagellate Dunaliella tertiolecta Butcher was grown with short photoperiods of bright light, the use of ammonia rather than nitrate as a nitrogen source led to a 30 % reduction of the doubling time of cell matter. The cell cycle (onset of light to completion of cell division) was shortened by about 10% only. Ammonia-grown cells possessed a greater capacity for photosynthetic oxygen evolution at light saturation than did nitrate-grown cells; their content of ribulosediphosphate carboxylase was likewise greater. The faster growth of Dunaliella tertiolecta with ammonia may be partly a consequence of a general increase in net protein synthesis resulting in a greater content of photosynthetic enzymes.