Photosynthetic response to salt of aquatic-living colonies of the terrestrial cyanobacterium Nostocflagelliforme

Aquatic-living colonial filaments of the terrestrial cyanobacterium Nostoc flagelliforme, developed from single cells in laboratory under aquatic conditions, were cultured at different salt concentrations (0–400 mM), and their photosynthetic responses were investigated to see their physiological tolerance. Light-saturated photosynthesis, photosynthetic efficiency and dark respiration showed the highest values in treatments at 20 mM NaCl for 24 or 48 h incubation. Changes in salt level exerted little influence on light saturation point and light compensation point. Patterns of photosynthetic performance as a function of salt were the same after 48 h as those after 24 h treatment, with the largest values at 20 mM NaCl, though photochemical efficiency increased with increased NaCl concentrations in the colonies treated for 48 h. From an applied point of view, the laboratory-generated aquatic living colonies are able to tolerate salt stress when transferred from aquatic to terrestrial environments.