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How close we are to achieving commercially viable large-scale photobiological hydrogen production by cyanobacteria: a review of the biological aspects.

Sakurai H, Masukawa H, Kitashima M, Inoue K - Life (Basel) (2015)

Bottom Line: The products of photobiological systems are H2 and O2; the H2 can be used as the energy source of fuel cells, etc., which generate electricity at high efficiencies and minimal pollution, as the waste product is H2O.Overall, production of commercially viable algal fuels in any form, including biomass and biodiesel, is challenging, and the very few systems that are operational have yet to be evaluated.In this paper we will: briefly review some of the necessary conditions for economical production, summarize the reports of photobiological H2 production by cyanobacteria, present our schemes for future production, and discuss the necessity for further progress in the research needed to achieve commercially viable large-scale H2 production.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Photobiological Hydrogen Production, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan. sakurai@waseda.jp.

ABSTRACT
Photobiological production of H2 by cyanobacteria is considered to be an ideal source of renewable energy because the inputs, water and sunlight, are abundant. The products of photobiological systems are H2 and O2; the H2 can be used as the energy source of fuel cells, etc., which generate electricity at high efficiencies and minimal pollution, as the waste product is H2O. Overall, production of commercially viable algal fuels in any form, including biomass and biodiesel, is challenging, and the very few systems that are operational have yet to be evaluated. In this paper we will: briefly review some of the necessary conditions for economical production, summarize the reports of photobiological H2 production by cyanobacteria, present our schemes for future production, and discuss the necessity for further progress in the research needed to achieve commercially viable large-scale H2 production.

No MeSH data available.


Outline of H2-related metabolic routes in heterocyst-forming cyanobacteria. Vegetative cells synthesize saccharides (CH2O) by ordinary photosynthesis with accompanying evolution of O2 and uptake of CO2. Heterocysts receive the saccharides, and use them (accompanied by CO2 evolution) as the sources of e− for N2ase reaction. For efficient net production of H2, H2ase(s) (uptake H2ase Hup and bidirectional H2ase Hox) have been inactivated. C6P: hexose phosphate, Fdox and Fdred: ferredoxin oxidized and reduced respectively, OPPP: oxidative pentose phosphate pathway, PSI and PSII: photosystem I and II, respectively (adapted from [21] with modification).
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life-05-00997-f002: Outline of H2-related metabolic routes in heterocyst-forming cyanobacteria. Vegetative cells synthesize saccharides (CH2O) by ordinary photosynthesis with accompanying evolution of O2 and uptake of CO2. Heterocysts receive the saccharides, and use them (accompanied by CO2 evolution) as the sources of e− for N2ase reaction. For efficient net production of H2, H2ase(s) (uptake H2ase Hup and bidirectional H2ase Hox) have been inactivated. C6P: hexose phosphate, Fdox and Fdred: ferredoxin oxidized and reduced respectively, OPPP: oxidative pentose phosphate pathway, PSI and PSII: photosystem I and II, respectively (adapted from [21] with modification).

Mentions: In this review, we will discuss mainly Group 1 cyanobacteria, as these strains are the focus of our research and because they are the most extensively studied among the three groups with respect to physiology, molecular biology, etc. [24,25,26]. The cells are organized as filaments, with the majority of the cells (called vegetative cells) synthesizing organic compounds by ordinary photosynthesis. Under combined-nitrogen deficiency a few of the cells develop into heterocysts, cells specialized for nitrogen fixation. Heterocysts lacking photosystem II activity, have increased respiration and are surrounded by a thick cell envelope that impedes the entry of O2, thus providing a micro-oxic environment to protect the N2ase from inactivation by O2. They receive saccharides from neighboring vegetative cells and the saccharides are then used as the electron donors for the N2ase reaction (Figure 2). Within heterocysts, photosystem I reduces low-potential ferredoxin and/or flavodoxin and contributes to the generation of ATP through photophosphorylation. The fixed nitrogen is converted to glutamine, which is transported to vegetative cells. In this manner, heterocystous cyanobacteria are able to simultaneously perform O2-evolving photosynthesis and the O2-labile N2ase reaction.


How close we are to achieving commercially viable large-scale photobiological hydrogen production by cyanobacteria: a review of the biological aspects.

Sakurai H, Masukawa H, Kitashima M, Inoue K - Life (Basel) (2015)

Outline of H2-related metabolic routes in heterocyst-forming cyanobacteria. Vegetative cells synthesize saccharides (CH2O) by ordinary photosynthesis with accompanying evolution of O2 and uptake of CO2. Heterocysts receive the saccharides, and use them (accompanied by CO2 evolution) as the sources of e− for N2ase reaction. For efficient net production of H2, H2ase(s) (uptake H2ase Hup and bidirectional H2ase Hox) have been inactivated. C6P: hexose phosphate, Fdox and Fdred: ferredoxin oxidized and reduced respectively, OPPP: oxidative pentose phosphate pathway, PSI and PSII: photosystem I and II, respectively (adapted from [21] with modification).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390889&req=5

life-05-00997-f002: Outline of H2-related metabolic routes in heterocyst-forming cyanobacteria. Vegetative cells synthesize saccharides (CH2O) by ordinary photosynthesis with accompanying evolution of O2 and uptake of CO2. Heterocysts receive the saccharides, and use them (accompanied by CO2 evolution) as the sources of e− for N2ase reaction. For efficient net production of H2, H2ase(s) (uptake H2ase Hup and bidirectional H2ase Hox) have been inactivated. C6P: hexose phosphate, Fdox and Fdred: ferredoxin oxidized and reduced respectively, OPPP: oxidative pentose phosphate pathway, PSI and PSII: photosystem I and II, respectively (adapted from [21] with modification).
Mentions: In this review, we will discuss mainly Group 1 cyanobacteria, as these strains are the focus of our research and because they are the most extensively studied among the three groups with respect to physiology, molecular biology, etc. [24,25,26]. The cells are organized as filaments, with the majority of the cells (called vegetative cells) synthesizing organic compounds by ordinary photosynthesis. Under combined-nitrogen deficiency a few of the cells develop into heterocysts, cells specialized for nitrogen fixation. Heterocysts lacking photosystem II activity, have increased respiration and are surrounded by a thick cell envelope that impedes the entry of O2, thus providing a micro-oxic environment to protect the N2ase from inactivation by O2. They receive saccharides from neighboring vegetative cells and the saccharides are then used as the electron donors for the N2ase reaction (Figure 2). Within heterocysts, photosystem I reduces low-potential ferredoxin and/or flavodoxin and contributes to the generation of ATP through photophosphorylation. The fixed nitrogen is converted to glutamine, which is transported to vegetative cells. In this manner, heterocystous cyanobacteria are able to simultaneously perform O2-evolving photosynthesis and the O2-labile N2ase reaction.

Bottom Line: The products of photobiological systems are H2 and O2; the H2 can be used as the energy source of fuel cells, etc., which generate electricity at high efficiencies and minimal pollution, as the waste product is H2O.Overall, production of commercially viable algal fuels in any form, including biomass and biodiesel, is challenging, and the very few systems that are operational have yet to be evaluated.In this paper we will: briefly review some of the necessary conditions for economical production, summarize the reports of photobiological H2 production by cyanobacteria, present our schemes for future production, and discuss the necessity for further progress in the research needed to achieve commercially viable large-scale H2 production.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Photobiological Hydrogen Production, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan. sakurai@waseda.jp.

ABSTRACT
Photobiological production of H2 by cyanobacteria is considered to be an ideal source of renewable energy because the inputs, water and sunlight, are abundant. The products of photobiological systems are H2 and O2; the H2 can be used as the energy source of fuel cells, etc., which generate electricity at high efficiencies and minimal pollution, as the waste product is H2O. Overall, production of commercially viable algal fuels in any form, including biomass and biodiesel, is challenging, and the very few systems that are operational have yet to be evaluated. In this paper we will: briefly review some of the necessary conditions for economical production, summarize the reports of photobiological H2 production by cyanobacteria, present our schemes for future production, and discuss the necessity for further progress in the research needed to achieve commercially viable large-scale H2 production.

No MeSH data available.