Chlamydomonas mutant hpm91 lacking PGR5 is a scalable and valuable strain for algal hydrogen (H2) production

Clean and sustainable H2 production is essential toward a carbon-neutral world. H2 generation by Chlamydomonas reinhardtii is an attractive approach for solar-H2 from H2O. However, it is currently not scalable because of lacking ideal strains. Here, we explore hpm91 , a previously reported PGR5-deletion mutant with remarkable H2 production, that possesses numerous valuable attributes towards large-scale application and in-depth study issues. We show that hpm91 is at least 100-fold scalable (upto 10 liter) with H2 collection sustained for averagely 26 days and 7287 ml H2/10L-HPBR. Also, hpm91 is robust and active over the period of sulfur-deprived H2 production, most likely due to decreased intracellular ROS relative to wild type. Moreover, quantitative proteomic analysis revealed its features in photosynthetic antenna, primary metabolic pathways and anti-ROS responses. Together with success of new high-H2-production strains derived from hpm91 , we highlight that hpm91 is a potent strain toward basic and applied research of algal-H2 photoproduction. ### Competing Interest Statement The authors have declared no competing interest.