Mykhailenko N. Lipid composition of Cyanophyta (Cyanobacteria) and fluorescence characteristics of their photosynthetic machinery under alternative conditions of carbon nutrition

The dissertation covers the analysis of lipid composition and efficiency of photochemical reactions in Cyanophyta (Cyanobacteria) under alternative modes of nutrition. The cultivation of Cyanophyta in the presence of exogenous glucose results in the redistribution of the ratio between polar lipids in favour of phosphatidylglycerol at the expense of monogalactosyldiacylglycerol; in the increase in relative content of oleate in lipids; in the derangement of chlorophyll biosynthesis; and in the inhibition of photosynthetic activity, namely in the lowering in the maximal quantum yield of photosystem II, reduced efficiency of photochemical charge separation in photosystem II reaction centres and impaired electron efflux from them. The results obtained in the work allow to draw a conclusion that glucose performs the signalling role in the cells of Cyanophyta, besides the metabolic function. This is proved by the changes in lipid composition, similar to those induced by glucose, that provokes mannose, the non-metabolizable structural analogue of glucose. The inhibitory effect of glucose analogues on photosystem II activity is restricted to the partial blocking of electron transfer from the reaction centres to plastoquinone pool.