Sulfur or nitrogen (N) deprivation promoted H2 production by C. pyrenoidosa 689S and 707Sincubated in ASW, while phosphorous (P) deprivation did not improve H2 production effectively. Changes of culture medium from ASW-S to TAP′S induced an increase of ~14% and 200% in H2 yield in C. pyrenoidosa 689S and 707S respectively