Here after referred to the standard growth condition: cells were grown in 100 ml of the standard BG-11 medium using 250-ml Erlenmeyer flask (Rippka, Deruelles et al. 1979), maintaining pH by 10 mM HEPES (4-(2- hydroxyethyl)-1-piperazineethanesulfonic acid) pH 7.5, and under the continuous white light of 50 μmol photons m-2s-1 and shaking at 130 round per min at 28 oC.