Action spectrum for an enhancement of endogenous respiration by light in chlorella.

The oxygen consumption of a starved chlorophyll-free, yellow mutant of Chlorella vulgaris is enhanced by very small amounts of blue light (lambda 450 mmu); a saturation level is reached at about 500 ergs cm(-2) sec(-1). At that intensity the respiration is about 3 times greater than in the dark. An action spectrum for the enhancement of respiration shows 2 peaks around lambda 450 and 375 mmu. Flavins and cis-carotenoids are discussed as the pigments involved.