PHOTOSYNTHETIC ACTIVITY OF 2 DEVELOPMENTAL STAGES OF A NOSTOC STRAIN (CYANOBACTERIA) ISOLATED FROM GEOSIPHON-PYRIFORME (MYCOTA)

Sessile colonies and motile hormogonia, the two main developmental sta ges in the life cycle of a Nostoc strain isolated from the endocytobio sis with Geosiphon pyriforme (Kutzing) F. v. Wettstein, were investiga ted for their photosynthetic competence. Large-scale fractionation of the two stages is presented. Photosynthetic parameters were assessed b y measurement of chlorophyll fluorescence and oxygen evolution. Hormog onia were as photosynthetically competent as the colonial stage. In ad dition, hormogonia showed an enhanced capability for nonradiative diss ipation of absorbed light energy, a feature that might be important fo r their function as propagula. Data for the quantum yield of photosyst em II of the isolated Nostoc strain were compared to the values determ ined in situ in G. pyriforme and indicated the possibility of a higher photosynthetic capacity of the endosymbiotic as compared to the isola ted cyanobacterium.