Growth of C. watsonii WH8501 batch cultures over a 6-day period under three CO2 treatments.

Shown are concentrations of PN (a), PC (b), and cells (c), molar C:N ratios (d), and pCO2 in µatm (e) within each treatment. For (a–c), the concentrations for each time point (Table S1) were first normalized to the concentration at the day 1 L6 time point, then ln-transformed. The derived slopes between day 1 L6 and day 3 L6 time points correspond to the exponential growth rates (µ) as shown in Table 2. The lines in (a) represent linear regressions through the day 1, day 2, and day 3 L6 time points for high-CO2 (dashed line) and low-CO2 (dotted line) treatments. The regression lines have been extended to the full time period (day 0–5) for visualization of exponential growth (day 0–3 L6 time points) transitioning to early stationary growth (L6 time points after day 3). The dotted line in (d) represents the 6.6 C:N ratio expected from Redfield stoichiometry. Shaded areas represent the dark periods. Error bars represent standard deviations from three replicates.