Hydrogen production by sulfur-deprived TiO2-encapsulated Chlamydomonas reinhardtii cells

• A method for TiO2-encapsulation of Chlamydomonas reinhardtii is described.
• We have pointed a crucial step to overcome the catalytic peptide toxicity.
• Hydrogen production of TiO2-encapsulated C. reinhardtii is analyzed.
• TiO2-encapsulated C. reinhardtii were able to produce more hydrogen compared to the non-modified counterparts.
• An estimate of the potential for the light-to-H2 conversion efficiency of modified cells is given.

Encapsulation of individual Chlamydomonas reinhardtii cells with TiO2 shells was found to affect their hydrogen production under sulfur-deprived conditions. We showed that a dark incubation of the cells before exposure to light is essential in order to overcome the toxic effects of the (RKK)4D8 catalytic peptide. The TiO2-encapsulated cells were able to produce H2 with about double efficiency during 5-day period compared to non-encapsulated cells. The light-to-H2 conversion efficiency of TiO2-encapsulated L159I–N230Y C. reinhardtii system was estimated to be more than 4% under optimized conditions.