Abstract
Increasing blue light intensity inhibits the growth of Chlorella pyrenoidosa in glucose culture in which photosynthesis is blocked by DCMU, whereas red light supports growth which is the same as or better than that in dark controls. The action spectrum of light induced protein synthesis from exogenous glucose (photosynthesis inhibited, blue light addition resulting in growth >90% of the dark control) shows only one broad maximum at 450–490 nm which resembles the absorption spectrum of carotenoids.