Previous work from our laboratory demonstrated the feasibility of using sulfur-deprived algal cultures to photoproduce H2 continuously for 3-4 days (Melis et al., 2000; Ghirardi et al., 2000a). The production of H2 depends mostly on the photosynthetic H2O-oxidation activity of the cultures (Ghirardi et al., 2000 a and b; Kosourov et al., 2002), and requires concomitant operation of O2-consumpti...
