The Influence of Light of Different Spectral Qualities on the Photosynthetic Characteristics of C-Phycocyanine-Containing Cyanobacteria Synechococcus sp. WH5701

Abstract

It has been found that cell volumes of the Synechococcus sp. WH5701 strain of cyanobacteria, as well as the intracellular contents of chlorophyll a and C-phycocyanin, did not depend of the spectral qualities of light. Chlorophyll a specific light absorption coefficients by pigments at wavelengths of 438 and 678 nm in cells adapted to blue light were higher than in cells adapted to white light by 20 and 50%, respectively. It was found that the quantum yield and the cell growth rate of Synechococcus sp. WH5701 depended on the spectral composition of the light. The value of the maximum quantum yield was at a minimum under blue light adaptation and at a maximum under adaptation to red light. An inverse relationship was revealed between the chlorophyll a specific light absorption coefficients and the quantum yield of growth, because in cyanobacteria, unlike eukaryotic microalgae, photosynthesis and growth depend on quanta absorbed only by phycobilin pigments, but not by all pigments. This peculiarity depends on the specific structure and function of the photosynthetic apparatus of cyanobacteria.