Photosynthetic hydrogen production

Physiologia Plantarum, 2021

Photosynthetic production of molecular hydrogen (H2) by cyanobacteria and green algae is a potential source of renewable energy. These organisms are capable of water biophotolysis by taking advantage of photosynthetic apparatus that links water oxidation at Photosystem II and reduction of protons to H2 downstream of Photosystem I. Although the process has a theoretical potential to displace fossil fuels, photosynthetic H2 production in its current state is not yet efficient enough for industrial applications due to a number of physiological, biochemical, and engineering barriers. This article presents a short overview of the metabolic pathways and enzymes involved in H2 photoproduction in cyanobacteria and green algae and our present understanding of the mechanisms of this process. We also summarize recent advances in engineering photosynthetic cell factories capable of overcoming the major barriers to efficient and sustainable H2 production.

Engineering in Life Sciences, 2014

Photochemical & Photobiological Sciences, 2009

Detection of the D 0 →D 1 transition of β-carotene radical cation photoinduced in photosystem II T. Okubo, T. Tomo and T. Noguchi, Photochem. Photobiol. Sci.

This study explores the molecular and genetic strategies for a clean, non-polluting and renewable photobiological hydrogen production technology. Photobiological production of H 2 gas, through split of water (e -donor) into molecular H 2 and O 2 using sunlight, is a property of two types of photosynthetic microorganisms: green algae and cyanobacteria. Interestingly, water splitting in each of these organisms is functionally linked to H 2 production by the activity of one of two major types of [FeFe] or [NiFe] hydrogenases. Both enzymes are phylogenetically distinct but perform the same catalytic reaction. The genetics, biosynthesis, structure, function, and O 2 sensitivity of these enzymes have been focus of extensive research in recent years. However, the hydrogen yield associated with these organisms remains far too low to compete with the existing chemical systems. This article summarizes the knowledge on the intrinsic incompatibility of photosynthetic microorganisms and strategi...

1979

This report was prepared as an account of work sponsored by an agency of t h e United States Government. Neither the United States nor any agency thereof, nor m y of their employees, makes any warranty, expressed a implied, or assumes any legal liability or respensibility fcr any third party's use a the results of such use of any information, apparatus, product, or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. ' neled d i r e c t l y t o t h e enzyme ' f o r &I v i v o hydrogen production. Rates exceeding 170 pmoles o f Hz-mg ~h l-1-have been observed.

Biomimetics Learning from Nature, 2010

I believe that water will one day be used as a fuel, because the hydrogen and oxygen which constitute it, used separately or together, will furnish an inexhaustible source of heat and light. I therefore believe that, when coal deposits are oxidized, we will heat ourselves be means of water. Water is the coal of the future" Jules Verne, 1875

Hydrogen gas with the highest gravimetric energy density of all known fuels produces energy without giving rise to the notorious carbon emissions that damage the environment. A promising next-generation non-conventional resource, hydrogen yields energy to the tune of about 122kJ/g. Biological processes for hydrogen production proffer distinct advantages such as clean and green energy that may be economically attractive. Among several known processes, two processes viz. direct and indirect biohydrogen production are reported in algae and cyanobacteria, respectively. In the direct process, photosystem II (PSII) dependent and PSII independent reaction cascades operate, out of which the PSII independent process appears to be more efficient and economical. Here, under anoxic conditions (induced by blockage of PSII) electrons derived from endogenous substrates such as proteins and carbohydrates are channelized via cyt. b6f to PSI. The absorbance of light by reactive center of PSI subsequently allows transfer of the electrons to ferrodoxin and then to an active hydrogenase enzyme on the outer face of the thylakoid membrane. Under oxygen limiting conditions the hydrogenase is active and utilizes the electrons to reduce protons that are released out of the thylakoid membrane during ATP synthesis. Attractive as it may seem, recent breakthroughs in H2 photoproduction have been able to tap only about 15% of the theoretical maximum, suggesting room for substantial improvement in the energy yield. Urgent steps need to be taken in order to develop the technology for commercial scale production of biohydrogen. Certain approaches appear to be promising in this regard, viz. (i) reducing antenna size to minimize shading effect and to avoid loss of energy during transfer of photons from antenna to the reaction center with the overall effect of increasing conversion efficiency, (ii) enriching the quality of endogenous substrate that would enhance generation of electrons, (iii) enhancing the release of hydrogen ions entrapped in thylakoid membrane by using protonophores. Additionally in a fourth approach, efforts need to be taken for designing the photobioreactors that will minimize the loss of photons and ensure the availability of specific wavelengths of light for maximal hydrogen production. Experimental data pertaining to some of the approaches discussed above will be discussed in the presentation.

2010

Project continuation and direction determined annually by DOE Objectives • Engineer an [FeFe]-hydrogenase that is resistant to O 2 inactivation to function with aerobic H 2 production systems being developed in collaboration with Oak Ridge National Laboratory (ORNL) and the University of California, Berkeley (UC Berkeley). • Generate a recombinant photosynthetic cyanobacterial system for H 2 production that utilizes an [NiFe]hydrogenase with increased O 2 resistance. • Develop and optimize a physiological method to promote culture anaerobiosis and subsequent H 2 production activity in algae.

Energy Conversion and Management, 1995

The algal fermentation conditions for the hydrogen production were investigated to improve the photobiological hydrogen production by a combination of a marine green alga Chlamydomonas sp. MGA161 and a marine photosynthetic bacterium Rhodopseudomonas sp. W-1s.

1979