“…Different approaches have been proposed to increase the hydrogen production capacity in green algae (recently reviewed in Esquível et al 2011;Eroglu and Melis 2011;Antal et al 2011;Torzillo et al 2014;Dubini and Ghirardi 2014;Ghirardi 2015). In S-deprived C. reinhardtii, advances have been achieved by 1. optimization of cultivation parameters, such as Chl concentration, medium composition and pH, light intensity, CO 2 supply, and synchronization of cell division (Tsygankov et al 2002;Kosourov et al 2003;Laurinavichene et al 2004;Kim et al 2006;Giannelli et al 2009); 2. construction of photobioreactors and elaboration of special protocols for continuous and semi-continuous regimes of cultivation, including outdoor and largescale cultivations (Fedorov et al 2005;Oncel and Vardar-Sukan 2009;Scoma et al 2012); 3. immobilization/encapsulation of algal cells in alginate, agar, or other materials (Laurinavichene et al 2008;Kosourov and Seibert 2009;Rashid et al 2013;Antal et al 2014;Stojkovica et al 2015); 4. design of high hydrogen-producing mutants characterized by an elevated respiration rate, low CET, low trans-thylakoid proton gradient, modified starch metabolism, truncated light-harvesting antennae, more oxygen-tolerant H 2 ase, and screening of natural species (reviewed in Torzillo et al 2014;Dubini and Ghirardi 2014).…”