Accumulation of phycobiliproteins in cells of ancient cyanobacteria from arctic permafrost as dependent on the nitrogen source for growth

Analysis of the absorption spectra of cells and phycobilisomes of ancient v iable heterocystous cyanobacteria Nostoc sp. and Anabaena sp. isolated from frozen sediments of a Holocene lake and grown on various nitrogen sources revealed that the amount of C-phycoerythrin in relation to chlorophyll was the greatest when cells were grown on nitrogen-free medium; in the presence of nitrate salts or organic nitrogen sources such as asparagine and glutam ine, the content of C-phycoerythrin decreased. Conversely, the content of p hycocyanin increased in the presence of organic nitrogen sources. Glycine i nhibited the growth of cyanobacteria and reduced the content of C-phycoeryt hrin and phycocyanin. Ammonium salts completely inhibited growth. Accumulat ion of C-phycoerythrin was accompanied by a decrease in the content of caro tenoids. These results suggest that the ancient cyanobacteria studied are s imilar to modern nitrogen-fixing cyanobacteria in their capacity to fix mol ecular nitrogen and store it in the form of C-phycoerythrin molecules.