Synergistic enhancement of pulsed light-induced H2 photoproduction in Chlamydomonas cells by optimal sulfite concentration and light waveform

Pulsed light illumination stands out as a noteworthy technique for photosynthetic H₂ production, playing a crucial role in eliminating O₂ and activating hydrogenase enzymes. However, further improvements are essential to make H₂ photoproduction suitable for future commercial applications. In our study, we observed a distinct enhancement in pulsed light-induced H₂ photoproduction in the unicellular green alga Chlamydomonas reinhardtii when treated with the optimal concentration of the mild O₂ scavenger Na₂SO₃. This improvement was a result of reduced O₂ content, increased hydrogenase enzyme activity, and suppressed H₂-uptake activity. Furthermore, our findings indicate that exposing Na₂SO₃-treated C. reinhardtii to optimal light waveform continues to significantly boost pulsed light-induced H₂ photoproduction, attributed to the alleviation of impaired photosystem II activity. Altogether, the combined application of optimal sulfite concentration and light waveform effectively enhances pulsed light-induced photosynthetic H₂ production in the green alga C. reinhardtii.