Difference in nitrate reduction in “light” and “dark” stages of synchronously grown Chlorella pyrenoidosa and resultant metabolic changes¹

Using synchronized cells of Chlorella pyrenoidosa, the incorporation patterns of 14C into various metabolites with and without nitrogen sources were studied under steady-state and non steady-state conditions. From the patterns it was found that the smallest cells which are divided in the dark utilize nitrate and nitrite very little, if at all. The importance of ammonia for regulation of secondary flow for Chlorella is discussed and the suggested regulatory points are described.