FIG. 2.

Three-dimensional graph illustrating the effects of arginine and ammonium sulfate on cyanophycin accumulation. Cells of A. calcoaceticus strain ADP1 were cultivated for 44 h at 30°C in 250-ml Erlenmeyer flasks without baffles containing 100 ml of unbuffered MSM containing no sodium glutamate but different concentrations of ammonium sulfate (10 to 50 mM) as the nitrogen source. In addition, arginine was added at concentrations of 30 to 75 mM. All other medium constituents used were as described for the basic medium in Materials and Method. At the end of the experiment the cells were harvested by centrifugation, and the cyanophycin content was analyzed.