Oxygen sensitivity of algal H2- production

  • Maria L. Ghirardi
  • Robert K. Togasaki
  • Michael Seibert
Session 2 Biological Research

Abstract

Photoproduction of H2 by green algae utilizes electrons originating from the photosynthetic oxidation of water and does not require metabolic intermediates. However, algal hydrogenases are extremely sensitive to O2, which limits their usefulness in future commercial H2-production systems. We designed an experimental technique for the selection of O2-tolerant, H2-producing variants ofChlamydomonas reinhardtii based on the ability of wild-type cells to survive a short (20 min) exposure to metronidazole in the presence of controlled concentrations of O2. The number of survivors depends on the metronidazole concentration, light intensity, preinduction of the hydrogenase, and the presence or absence of O2. Finally, we demonstrate that some of the selected survivors in fact exhibit H2-production capacity that is less sensitive to O2 than the original wild-type population.

Index Entries

Hydrogen green algae Chlamydomonas oxygen metronidazole 

Abbreviations

ATP

adenosine triphosphate

cwl5

cell wall-less strain ofChlamydomonas reinhardtii

DCMU

3-(3,4-dichlorophenyl)-l,l-dimethylurea

Fd

ferredoxin

I50

inhibitor concentration that decreases the rate of an enzymatic reaction to 50% of the rate measured in the absence of the inhibitor

MNZ metronidazole

[l-(2-hydroxyethyl)-2-methyl-5-nitroimidazole]

NADP

nicotinamide adenine dinucleotide phosphate

NADPH

reduced form of NADP

Vo

initial rate of an enzymatic reaction

WT

wild-type

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Copyright information

© Humana Press Inc. 1997

Authors and Affiliations

  • Maria L. Ghirardi
    • 1
  • Robert K. Togasaki
    • 2
  • Michael Seibert
    • 1
  1. 1.Notional Renewable Energy LaboratoryGolden
  2. 2.Department of BiologyIndiana UniversityBloomington

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