Fig. 4. The open circuit potential (OCP) evolution of three used suspensions for microbial enrichment. (A) Synechocystis + BG-11 and Synechocystis + BG-11 + 40mM NH4Cl, (B)Synechocystis + BG-11 and Synechocystis + BG-11 + 50mM KCl.