FIG. 3.

Parameter profiles in a photobioreactor culture of C. tepidum with a regulated flow of H₂S as the sole electron source. Medium 1 without thiosulfate was used for this culture. Before inoculation, the redox potential of the medium was lowered to −320 mV by using manually controlled H₂S flow to the vessel. From then on, the H₂S flow was regulated by a control system set to maintain the culture redox potential at −300 ± 20 mV. For pH control, 2 M H₃PO₄ and 2 M NaOH were used. See the legend to Fig. 1 for other details.