NADPH fluorescence as an indicator of hydrogen production in the green algae Chlamydomonas reinhardtii

This study investigated cellular Nicotinamide Adenine Dinucleotide Phosphate (NADPH) fluorescence as a potential indicator of biohydrogen production in Chlamydomonas reinhardtii and a β-NADPH standard. NADPH fluorescence profiles of cultures grown in TAP-S (Tris-acetate phosphate minus sulphur) media, TAP (Tris-acetate phosphate) media and TAP + 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) were subsequently compared. Hydrogen production induced from sulphur depletion was found to correlate directly (r = 0.941) with NADPH over the ten day period. The addition of leachate was used to increase hydrogen yields, and subsequently increased the NADPH concentration by 50%-70%. A direct correlation was observed (r = 0.929) between NADPH and hydrogen when the leachate supplemented media was used. As NADPH is the terminal electron acceptor in the photosynthetic chain, results show that NADPH has a pivotal role in hydrogen production as a carrier molecule. Under sulphur depletion, cellular NADPH fluorescence can be used as an indicator of hydrogen production.