Glycogen synthesis prevents metabolic imbalance and disruption of photosynthetic electron transport from photosystem II during transition to photomixotrophy in Synechocystis sp. PCC 6803.

Some cyanobacteria can grow photoautotrophically or photomixotrophically by using simultaneously CO and glucose. The switch between these trophic modes and the role of glycogen, their main carbon storage macromolecule, was investigated. We analysed the effect of glucose addition on the physiology, metabolic and photosynthetic state of Synechocystis sp.

Stress response requires an efficient connection between glycogen and central carbon metabolism by phosphoglucomutases in cyanobacteria.

Glycogen and starch are the main storage polysaccharides, acting as a source of carbon and energy when necessary. Interconversion of glucose-1-phosphate and glucose-6-phosphate by phosphoglucomutases connects the metabolism of these polysaccharides with central carbon metabolism. However, knowledge about how this connection affects the ability of cells to cope with environmental stresses is still scarce.