A high yield mutant of Chlamydomonas reinhardtii for photoproduction of hydrogen

To identify genes important for the photoproduction of H₂ of Chlamydomonas reinhardtii, random insertional mutants, by the ble gene encoding the enzyme with zeomycin resistant properties, were screened for clones with changed H₂ production. One of the mutants, denoted T1, with 7.8-fold of H₂ yield and about 23% of respiration rate increased compared with the parental strain cc849 was obtained among the zeomycin-resistant transformants. The photosynthetic rate and Fv/Fm, the efficiency of PSII primary photochemistry of T1 declined. Therefore, the photosynthesis/respiration capacity ratio (P/R ratio) of T1 was reduced compared with strain cc849. However, the growth of the mutant T1 was not inhibited, indicating that T1 was a good mutant for further studies of the genes improving H₂ yield by lowering the photosynthetic capacity and/or enhancing the respiration capacity in C. reinhardtii, and had potential to be used in further improvement of H₂ generation by further biotechnological approaches.