Photobiological hydrogen production by marine green alga Platymonas subcordiformis under carbonylcyanide-m-chlorophenylhydrazone

The marine green alga Platymonas subcordiformis can produce a significant amount of hydrogen under anaerobic condition and the addition of a proton gradient uncoupler, carbonylcyanide-m-chlorophenylhydrazone (CCCP). About 7.54 ml H₂ was produced at 3×10⁶ cells · ml^-1 for 12 h in a 760 ml photobioreactor when 15 μmol·L^-1 CCCP was added at the beginning of light illumination. During the stage of hydrogen evolution, the extracellular pH and the photochemical activity of PS II reduced from 7.62 to 7.49 and from 0.342 to 0.002, respectively. The system held at a very low oxygen level. These results indicate that the proton gradient uncoupler CCCP can facilitate the proton transfer across the thylakoid membrane, thus enhance the accessibility of H⁺ to hydrogenase, and keet anaerobic condition during hydrogen production through markedly inhibition of the PS II activity.