Metabolic pathways for photobiological hydrogen production by nitrogenase- and hydrogenase-containing unicellular cyanobacteria Cyanothece
| Autor: | Gennady Ananyev, Nicholas J. Skizim, G. Charles Dismukes, Anagha Krishnan |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Cyanobacteria
Hydrogenase food.ingredient Cyanothece Plastoquinone Bioenergetics Biochemistry chemistry.chemical_compound food Bacterial Proteins Nitrogenase Molecular Biology Hydrogen production biology Photosystem I Protein Complex Photosystem II Protein Complex Cell Biology biology.organism_classification Metabolic pathway chemistry Flux (metabolism) Hydrogen |
| Zdroj: | The Journal of biological chemistry. 287(4) |
| ISSN: | 1083-351X |
| Popis: | Current biotechnological interest in nitrogen-fixing cyanobacteria stems from their robust respiration and capacity to produce hydrogen. Here we quantify both dark- and light-induced H(2) effluxes by Cyanothece sp. Miami BG 043511 and establish their respective origins. Dark, anoxic H(2) production occurs via hydrogenase utilizing reductant from glycolytic catabolism of carbohydrates (autofermentation). Photo-H(2) is shown to occur via nitrogenase and requires illumination of PSI, whereas production of O(2) by co-illumination of PSII is inhibitory to nitrogenase above a threshold pO(2). Carbohydrate also serves as the major source of reductant for the PSI pathway mediated via nonphotochemical reduction of the plastoquinone pool by NADH dehydrogenases type-1 and type-2 (NDH-1 and NDH-2). Redirection of this reductant flux exclusively through the proton-coupled NDH-1 by inhibition of NDH-2 with flavone increases the photo-H(2) production rate by 2-fold (at the expense of the dark-H(2) rate), due to production of additional ATP (via the proton gradient). Comparison of photobiological hydrogen rates, yields, and energy conversion efficiencies reveals opportunities for improvement. |
| Databáze: | OpenAIRE |
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