FIG. 2.

Parameter profiles in a photobioreactor culture of C. tepidum with sodium sulfide (2.5 mM) added as the sole electron source at the start and no gas flow through the vessel until 80 h of culture age. Medium 1 without thiosulfate was used for this culture. Before inoculation, the sterilized anaerobic medium was placed under a headspace of N₂-CO₂ (80:20; 3 × 10⁴ Pa), the vessel exhaust was closed, and sodium sulfide was added to the medium. At 80 h of culture age, the vessel exhaust was opened and N₂-CO₂ flow at a rate of 750 ml min⁻¹ (as an overlay) was initiated. Except for the first few hours, in the period until 80 h of culture age, the culture was brown in color. The culture pH was not controlled. See the legend to Fig. 1 for other details.