Effects of Flashes of Red or Blue Light on the Composition of Starved Chlorella pyrenoidosa

Autotrophically grown cells of Chlorella pyrenoidosa (211-8b) were starved 3 to 4 days in darkness, flashes of blue light, or flashes of red light. The blue flashes were sufficient to maintain the maximal rate of light-stimulated oxygen uptake during short term experiments. However, after 24 hours, the respiration rate in red flashes was equal to, or greater than, the rate in blue flashes. Starvation in darkness reduced the chlorophyll content by 11%, altered the blue absorbance of the nonsaponifiable material only 1 to 2%, and reduced the dry weight by 13%. Starvation in the presence of blue or red flashes reduced the dry weight by an additional 11 or 12% respectively. Protein per unit cell volume was not changed significantly during 3 to 4 days starvation in darkness or in blue flashes, even though dry weight per unit cell volume decreased 13% in darkness and 23% in blue flashes. In contrast, cells starved under red flashes showed a 20% decrease in protein per unit cell volume and a 24% decrease in dry weight per unit cell volume.