Dried exhibits nitrogen-fixing activity using glucose under dark conditions after rehydration.

is an edible cyanobacterium that produces a massive gelatinous polysaccharide matrix around the filamentous cells. The polysaccharides, more than 70% of which comprise glucose, are essential for resistance to environmental stresses. In the present study, we collected naturally growing colonies, dried them for preservation, rehydrated them, and then examined their nitrogen-fixing activity using the acetylene reduction method. As expected, the rehydrated performed nitrogen fixation after illumination with white light. Notably, under dark, aerobic conditions, the rehydrated exhibited nitrogen fixation in the presence of glucose. In contrast, under dark, anaerobic conditions, nitrogen fixation was low. Because the natural habitats of are aerobic but lack carbohydrates, cells may exhibit glucose utilization activity constitutively.