Biotechnology of Hydrogen Production with the Microalga Chlamydomonas reinhardtii

The increase in the cost of energy and the problem of global warming have fostered considerable international efforts to discover a sustainable way to produce energy with zero CO 2 emission. One eco-friendly way of producing energy is the photobiological production of H 2 using the microalga Chlamydomonas reinhardtii . In speci fi c conditions, this organism can direct electrons and protons obtained from water biophotolysis toward a speci fi c enzyme, an [Fe]-hydrogenase, so as to obtain molecular H 2 . The process was discovered by Gaffron and Rubin ( 1942 ), who observed a transient H 2 production with Scenedesmus . A way to prolong H 2 production by means of inorganic sulfur deprivation was discovered by Melis and coworkers (Melis et al., 2000 ) . In the past 10 years, considerable progress has been achieved in the photobiological production of hydrogen using Chlamydomonas under sulfur starvation conditions, and this has resulted in a number of papers being published on this subject (Melis et al., 2000 ; Kosourov et al., 2002, 2005, 2007 ; Tsygankov et al., 2002, 2006 ; Zhang et al., 2002 ) . This chapter will brie fl y summarize the advancements made and the current barriers that need to be overcome for the scale-up to outdoor conditions so as to improve the feasibility of the process.