Water-splitting-based, sustainable and efficient H2 production in green algae as achieved by substrate limitation of the Calvin–Benson–Bassham cycle

Table 1 Light-to-H₂ energy conversion efficiency in Chlamydomonas reinhardtii in HS medium under various conditions

Conditions of H₂ production	Time of illumination following dark anaerobic incubation (h)
Conditions of H₂ production	0.25	1	3	5	24
Control (HS)
H₂ produced (µl/ml)	3.46	3.86	8.41	10.80	27.47
Efficiency (%)	1.43	0.40	0.29	0.22	0.11
+ Glc + GO + Asc
H₂ produced (µl/ml)	n.d.	38.57	85.33	92.68	117.04
Efficiency (%)	n.d.	4.00	2.95	1.92	0.51
+ O₂ absorbent
H₂ produced (µl/ml)	3.85	6.73	13.09	19.20	62.10
Efficiency (%)	1.60	0.70	0.45	0.40	0.27

Algal cultures containing 50 µg chl (a + b)/ml and dark-incubated for 4 h were illuminated using cool white fluorescent tubes, at an intensity of 52 W/m², corresponding to approx. 320 µmol photons/m²/s. See “Materials and methods” for the calculations on the incident light-to-H₂ conversion efficiency. The experiments were carried out in HS medium (control) and the effects of a combined glucose (Glc, 2 mM), glucose oxidase (GO, 0.2 mg/ml) and ascorbate (Asc, 1 mM) treatment and the effects of an iron-salt O₂ absorbent were also assessed
nd non-determined

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