Fig. 3.

Effects of carbon and nitrogen concentrations on the growth and pigmentation of Synechocystis. (A) Photograph of Synechocystis cell cultures harvested on day 11. Concentrations of NaHCO₃ and NaNO₃ are shown. Cell density (B), chlorophyll a (C) and phycocyanin (D) content, as estimated by absorption spectroscopy. The OD₇₃₀ value in (B) was measured with an integrating sphere and gave lower values of OD₇₃₀ compared with those measured with a conventional UV–Vis spectrometer. (B–D) The different concentrations of NaHCO₃ and NaNO₃ are shown as colored lines according to the legend.