Partitioning of CO2 Fixation in the Colonial Cyanobacterium Microcystis aeruginosa: Mechanism Promoting Formation of Surface Scums

摘要: Constraints on inorganic carbon (C i ) availability stimulated buoyancy in natural, photosynthetically active populations of the colonial blue-green alga (cyanobacterium) Microcystis aeruginosa. In nonmixed eutrophic river water and cultures, O 2 evolution determinations indicated C limitation photosynthesis, which was overcome either by CO additions to aqueous phase or exposure buoyant colonies atmospheric . Microautoradiographs M. aeruginosa revealed partitioning 14 fixation photosynthate accumulation between peripheral internal cells, particularly large colonies. When illuminated were suspended phase, cells accounted for at least 90% assimilation, whereas remained unlabeled. However, when allowed diffuse into 15 min before illumination, a more uniform distribution labeling observed. Resultant differences patterns most likely due exclusively utilizing ambient concentrations low. Among located air-water interface, showed an increased share production supplied. This that transport restricted below surface, forcing maintain high degree buoyancy, thus promoting formation surface scums. At restrictions alleviated. Accordingly, scum appears have ecological function, allowing cyanobacteria access concentration is growth limiting column. Images