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Lichen symbiosis: nature's high yielding machines for induced hydrogen production.

Papazi A, Kastanaki E, Pirintsos S, Kotzabasis K - PLoS ONE (2015)

Bottom Line: Hydrogen is a promising future energy source.Although the ability of green algae to produce hydrogen has long been recognized (since 1939) and several biotechnological applications have been attempted, the greatest obstacle, being the O2-sensitivity of the hydrogenase enzyme, has not yet been overcome.It has been hypothesized that the mycobiont's and photobiont's consumption of oxygen (increase of COX and AOX proteins of mitochondrial respiratory pathways and PTOX protein of chrolorespiration) establishes the required anoxic conditions for the activation of the phycobiont's hydrogenase in a closed system.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Crete, Voutes University Campus, Heraklion, Crete, Greece.

ABSTRACT
Hydrogen is a promising future energy source. Although the ability of green algae to produce hydrogen has long been recognized (since 1939) and several biotechnological applications have been attempted, the greatest obstacle, being the O2-sensitivity of the hydrogenase enzyme, has not yet been overcome. In the present contribution, 75 years after the first report on algal hydrogen production, taking advantage of a natural mechanism of oxygen balance, we demonstrate high hydrogen yields by lichens. Lichens have been selected as the ideal organisms in nature for hydrogen production, since they consist of a mycobiont and a photobiont in symbiosis. It has been hypothesized that the mycobiont's and photobiont's consumption of oxygen (increase of COX and AOX proteins of mitochondrial respiratory pathways and PTOX protein of chrolorespiration) establishes the required anoxic conditions for the activation of the phycobiont's hydrogenase in a closed system. Our results clearly supported the above hypothesis, showing that lichens have the ability to activate appropriate bioenergetic pathways depending on the specific incubation conditions. Under light conditions, they successfully use the PSII-dependent and the PSII-independent pathways (decrease of D1 protein and parallel increase of PSaA protein) to transfer electrons to hydrogenase, while under dark conditions, lichens use the PFOR enzyme and the dark fermentative pathway to supply electrons to hydrogenase. These advantages of lichen symbiosis in combination with their ability to survive in extreme environments (while in a dry state) constitute them as unique and valuable hydrogen producing natural factories and pave the way for future biotechnological applications.

No MeSH data available.


Related in: MedlinePlus

Kinetic of hydrogen production of the lichen Pleurosticta acetabulum in several initial volumes of culture medium.
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pone.0121325.g003: Kinetic of hydrogen production of the lichen Pleurosticta acetabulum in several initial volumes of culture medium.

Mentions: This hypothesis was the main reason for testing the lichen’s hydrogen release in several liquid culture medium volumes (10, 25, 50 and 100 mL). The results for oxygen concentration were the expected ones (increase of medium volume led to decrease of oxygen—data not shown), but the hydrogen productivities based on the hydrogen measurements in the air space were exactly the opposite. The higher the medium volume the lower the hydrogen production measured, as it is shown in Fig. 3. This was mainly due to the partial pressure of the gases in the air-liquid interface, as analytically explained in our previous publication [17]. The increase of the culture medium volume led to faster oxygen depleted conditions, but the partial pressures did not permit the release of the produced hydrogen from the liquid phase to the air phase in order to be detected by the gas chromatographer. During each sampling, where there was a small air decompression (in the upper air phase), air bubbles appeared in the liquid phase (culture medium) which immediately moved to the air phase of the hermitically closed bottle, because of the new pressure balance.


Lichen symbiosis: nature's high yielding machines for induced hydrogen production.

Papazi A, Kastanaki E, Pirintsos S, Kotzabasis K - PLoS ONE (2015)

Kinetic of hydrogen production of the lichen Pleurosticta acetabulum in several initial volumes of culture medium.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380476&req=5

pone.0121325.g003: Kinetic of hydrogen production of the lichen Pleurosticta acetabulum in several initial volumes of culture medium.
Mentions: This hypothesis was the main reason for testing the lichen’s hydrogen release in several liquid culture medium volumes (10, 25, 50 and 100 mL). The results for oxygen concentration were the expected ones (increase of medium volume led to decrease of oxygen—data not shown), but the hydrogen productivities based on the hydrogen measurements in the air space were exactly the opposite. The higher the medium volume the lower the hydrogen production measured, as it is shown in Fig. 3. This was mainly due to the partial pressure of the gases in the air-liquid interface, as analytically explained in our previous publication [17]. The increase of the culture medium volume led to faster oxygen depleted conditions, but the partial pressures did not permit the release of the produced hydrogen from the liquid phase to the air phase in order to be detected by the gas chromatographer. During each sampling, where there was a small air decompression (in the upper air phase), air bubbles appeared in the liquid phase (culture medium) which immediately moved to the air phase of the hermitically closed bottle, because of the new pressure balance.

Bottom Line: Hydrogen is a promising future energy source.Although the ability of green algae to produce hydrogen has long been recognized (since 1939) and several biotechnological applications have been attempted, the greatest obstacle, being the O2-sensitivity of the hydrogenase enzyme, has not yet been overcome.It has been hypothesized that the mycobiont's and photobiont's consumption of oxygen (increase of COX and AOX proteins of mitochondrial respiratory pathways and PTOX protein of chrolorespiration) establishes the required anoxic conditions for the activation of the phycobiont's hydrogenase in a closed system.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Crete, Voutes University Campus, Heraklion, Crete, Greece.

ABSTRACT
Hydrogen is a promising future energy source. Although the ability of green algae to produce hydrogen has long been recognized (since 1939) and several biotechnological applications have been attempted, the greatest obstacle, being the O2-sensitivity of the hydrogenase enzyme, has not yet been overcome. In the present contribution, 75 years after the first report on algal hydrogen production, taking advantage of a natural mechanism of oxygen balance, we demonstrate high hydrogen yields by lichens. Lichens have been selected as the ideal organisms in nature for hydrogen production, since they consist of a mycobiont and a photobiont in symbiosis. It has been hypothesized that the mycobiont's and photobiont's consumption of oxygen (increase of COX and AOX proteins of mitochondrial respiratory pathways and PTOX protein of chrolorespiration) establishes the required anoxic conditions for the activation of the phycobiont's hydrogenase in a closed system. Our results clearly supported the above hypothesis, showing that lichens have the ability to activate appropriate bioenergetic pathways depending on the specific incubation conditions. Under light conditions, they successfully use the PSII-dependent and the PSII-independent pathways (decrease of D1 protein and parallel increase of PSaA protein) to transfer electrons to hydrogenase, while under dark conditions, lichens use the PFOR enzyme and the dark fermentative pathway to supply electrons to hydrogenase. These advantages of lichen symbiosis in combination with their ability to survive in extreme environments (while in a dry state) constitute them as unique and valuable hydrogen producing natural factories and pave the way for future biotechnological applications.

No MeSH data available.


Related in: MedlinePlus