Adaptive variability of pigments in representatives of the genus Nostoc Vauch. (Cyanophyta) under different light conditions

Changes in the composition, content of pigments (chlorophyll a (Chl), carotenoids, phycobiliproteins: phycoerythrin (PE), phycocyanin (PC), allophycocyanin (APC) and accumulation of biomass in Nostoc muscorum Ag., St. 81 and Nostoc punctiforme (Kutz.) Hariot., st. 39 have been studied under conditions of different light intensity. Variations in the light intensity can provoke an adaptive response of algae by the feedback type between the level of photoactive radiation and the content of pigments. It has been established that under low illumination conditions the content of all phycobilin pigments essentially changed, that of chlorophyll a - to a lesser extent, and of carotenoids it was the least. The content of phycoerythrin changed to the greatest extent under intensive illumination conditions. Definite limits of variability were established for all types of pigments of each culture studied. The most variable values were in the PE/Chl ratios, more stable in the PE/PC and APC/Chl ratios, and also in carotenoids. The studied species of the genus Nostoc revealed different biochemical variability patterns in the pigment apparatus under influence of the illumination regime. It should be taken into account for comparative characterization of species.