Metabolic Responses of Cyanobacteria in Increasing Salinity Levels

By: Irene Leyendecker

Figure 1. This figure shows the response of two acclimated strains of M. aeruginosa to higher salinity concentrations between a period of 30 days. As you can see in the figure at the lowest salinity of 0.6 the growth of both strains reached a stationary phase after the exponential growth phase which was between the 4-28 days. During the exponential growth phase that occurred  the cell concentration increased slowly with higher salinities for both strains.


Microcystis is a toxic cyanobacteria that is found in freshwater ecosystems. A study was done to compare physiological responses of two strains of M. aeruginosa that were isolated from contrasting environments with increasing salinities. With higher salinity conditions there is a result of cell lysis which leads to the release of soluble microcystin into the water. When this toxin is released into the water it then affects marine organisms which then become food-borne and impact human health. It was found that higher salinity reduced the growth rate and the production rate of microcystin by M. aeruginosa. This salinity tolerance of cyanobacteria is due to the ability of cells to regulate their internal osmosis through the regulation of intracellular ionic balance. This is an important finding because freshwater ecosystems are expected to experience increased salinity due to climate change and environmental pollution from human activity.  Due to this study we know that these strains of M. aeruginosa can acclimate to higher salt concentrations and better assess salinity tolerance. With higher salinity there is a decrease in microcystin cellular quota, which is caused by cell lysis, therefore there is less of this toxin being released into the water.


Article Citation:
Georges des Aulnois M., Roux P., Caruana A., Reveillon D., Briand E., Herve F.,et al. (2019) Physiological and Metabolic Responses of Freshwater and Brackish-Water Strains of Microcystis aeruginosa Acclimated to a Salinity Gradient: insight into Salt Tolerance. Applied and Enviornmental Microbiology 85.