[Promoting effect of blue light on the production of carotenoids in a yellow chlorella mutant]

In growing as well as in resting cells of a chlorophyll-free yellow mutant of Chlorella vulgaris (211-11h/20) synthesis of carotenoids is enhanced by blue light. Permanent irradiation is necessary to maintain the effect (Fig. 2). At wavelengths around 454 nm the additional carotenoid production is half-saturated at about 1000 erg cm(-2)s(-1) and saturated at about 4000 erg cm(-2)s(-1) (Fig. 3). An action spectrum exhibits highest efficiency of wavelengths around 465 and 370 nm, a minimum near 400 nm and inefficacy of yellow, red and far-red light (Fig. 4). This wavelength dependence resembles those of light enhanced O2-uptake, carbohydrate consumption and gain of organically bound nitrogen by the organism.