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The growth of Synechococcus at different intensities of white and red light caused changes in the pigment composition. The ratio of chlorophyll a to phycocyanin varied from 1:8,2 in LWLI-grown cells to 1:1,4 in cells grown at HWLI and to 1:15,7 in cultures exposed to HRLI. Acyl lipids were quantitatively determ ined and fatty acids of the individual lipid classes analysed by GLC. Phycocyanin-free photosynthetic lam ellae were obtained by fractional centrifugation. No variation was found in the acyl lipid composition of the m em brane preparations. These all contained MGDG, DGDG, SQDG and PG as components. In all the lipids investigated, palmitic, hexadecenoic and octadecenoic acids m ade up to more than 90% of total fatty acids. The pattern of these major components w ithin the lipids from the different cultures depended on the light used. No large differences were detected between zones obtained from LWLI and HRLI isolated membranes, whereas density gradient centrifugation of those from HWLI-grown cells resulted in a completely different pattern of bands. The variations in lipid and fatty acid composition are discussed with respect to changes observed in lipid composition of whole cells and the results reported on tem perature dependent shifts in lipid fluidity in cyanobacteria.
The cyanobacterium Synechococcus leopoliensis (Anacystis nidulans, strain L 1402-1) grown at 39 °C and 2 vol. % CO : could be synchronized by a light/dark regime of 3:5 h (white light intensity 1.5 × 104 erg cm-2 sec-1). Content of pigments (chlorophyll a. phycocyanin and carotenoids), R N A and proteins increased linearly up to 100% at the end of the light period while DNA synthesis was lower. Chlorophyll a synthesis was correlated to the photosystem I activity of the isolated thylakoids and to the formation of MGD G . Galacto lipids were synthesized in the light period, only. A lag phase of 2h was observed in the biosynthesis of SQDG and PG. No significant differences were found between the cell and thylakoid fractions. Palmitic (C16:0), hexadecenoic (C16:1) and octadecenoic (C18:1) acid as major com ponents accounted for more than 90% of total fatty acids in MGD G , DGDG and SQDG . PG contains a small amount of stearic (C18:0) and heptadecenoic (C17:1) acid. No significant variations in the fatty acid distribution of all lipids could be detected in the cell fraction during the division cycle. Changes in the ratio of saturated to unsaturated fatty acids were found in isolated thylakoids. only. In experiments with [14C]bicarbonate main radioactivity was measured in galacto lipids while using [14C]acetate SQDG and PG were markedly [14C]labelled. Results were discussed with reference to the findings of eucaryotic algae and the formation of photosynthetic membranes.
The cyanobacterium Synechococcus (Anacystis nidulans, strain L 1401-1) grown under different light conditions showed variations in pigmentation. Ratios of photosynthetic pigments and the effect on quantum requirement and oxygen evolution were studied. An increase in the ratio of chlorophyll a forms with absorption maxima in the far red regime to total chlorophyll a forms was observed in cells grown in strong white light. The quantum efficiency of orange light (637 nm) - absorbed by phycocyanin - was higher after growth of Synechococcus in white than in red light. The quantum efficiency at 677 nm increased when cells were grown in red light and decreased strongly after transfering red light grown cells to conditions of strong white light. The results show an adaptation of pigment composition to light regimes during growth and its effect on photosynthesis.
Synechococcus (Anacystis nidulans, strain L 1402-1) were grown at + 37 °C in an atmosphere of 0.04 vol.% CO2 using different light conditions. Changing the culture conditions caused alterations in pigment ratios and ultrastructure of Synechococcus. In comparison to the low white and red light grown cells under strong white light the number of thylakoids decreased and an accumulation of storage carbohydrates could be observed. The number of the polyhedral bodies also varied with culture conditions. The results are discussed with reference to the pigment composition and the function of the polyhedral bodies.