CARBON AND NITROGEN BALANCE OF CHLORELLA DURING GROWTH

Open Access
Publisher Website
Google Scholar
Abstract
A continuous-culture apparatus was adapted to study of the C balance of C. pyrenoidosa during growth by glucose assimilation in the dark. About 49% of the glucose C was assimilated to cellular C and about 93% of the glucose C was recovered as CO2 and cellular C. A 2d method was devised for study of metabolism in mass algal cultures. The algal suspension occupied a small portion of a large bottle adapted to a roll culture. Gas exchange was measured by Haldane analysis. The method was applied to study of the C and N balance during photosynthetic growth. About 95% of the C taken up as CO2 and the N taken up as nitrate was recovered as cellular C and N. Recovery was about equally complete under light-limiting or light-saturating intensities for growth. A CO2/O2 exchange quotient of 0.7 at low light intensity (50 fc.) and with nitrate as N source confirms previous manometric measurements. The quotient of 0.76 observed at high light intensity (500 fc.) is significantly lower than the value 0.9 commonly reported from short-time manometric measurements. It is suggested that when Chlorella is first exposed to high light intensity its metabolism temporarily adjusts to an increased carbohydrate synthesis which permits the higher quotient of 0.9 observed in the usual short-time expts.