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[Duurzaamlijst] waterstof uit algen



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Date: Fri, 24 Mar 2000 17:37:07 +0100
From: wytze <geno@ZAP.A2000.NL>
To: GEN-TECH@NIC.SURFNET.NL
Subject: [GT] Look! no genetic engineering

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Biotech Activists wrote:

> ===================================================
> >From List:   Biotech Activists (biotech_activists@iatp.org)
> Date Posted: 03/24/2000
> Posted by:   M.W.Ho@open.ac.uk
> ===================================================
>
> This item is appearing in the upcoming issue of ISISnews(#4). It is a prime
> example of sustainable, environmentally friendly organic science and
> technology.
>
> Look! No Genetic Engineering
> Growing Hydrogen from Green Algae and Sunlight
>
> A research group headed by Anastasios Melis, a biochemist in the Department
> of Plant and Microbial Biology in University of California Berkeley, have
> made a sensational discovery. It has kept Melis' telephone buzzing ever
> since he gave a talk at the American Association for the Advancement of
> Science annual meeting earlier this year. They discover how to grow hydrogen
> gas from green algae and sunlight. Hydrogen is the cleanest renewable fuel
> around. The beauty of burning hydrogen is that you get pure water back, and
> already, motor-cars are under development that would burn hydrogen. (This
> may be a good way to purify water as a by-product!)
> The alga they are working with is the single-celled Chlamydomonas, which can
> be grown easily in the laboratory. Normally, it lives by photosynthsis, a
> process in which the energy of sunlight is absorbed by the green pigment
> chlorophyll to split water into its elements, hydrogen and oxygen. Actually,
> only oxygen is released, while hydrogen is separated into a positively
> charged proton and a negatively charged electron. The proton goes to reduce
> carbon dioxide to carbohydrates (CHO)n, while the electron goes through an
> electron transport chain to make ATP, the universal energy intermediate in
> living organisms. Some of the carbohydrates are oxidized, or combined back
> with oxygen to give carbon dioxide and water in respiration, in a reversal
> of photosynthesis.  The rest of the carbohydrates are converted into
> proteins, nucleic acids and other constituents of the cell which are
> necessary for growth and repair. Proteins contain nitrogen and also sulphur.
>
> It so happens that when the alga is deprived of sulphur and sealed tight but
> still exposed to sunlight, it switches to another metabolic state after 24
> to 30 h and begins to release hydrogen gas which is 87% pure. The rest is
> mostly nitrogen, with 1% carbon dioxide and traces of oxygen. And it can
> keep this up at least until 150 h.
> The precise source of the hydrogen is not yet known. It almost certainly
> involves a reversal of the charge separation process in photosynthesis, ie,
> electrons are recombined back with protons to give hydrogen. This reaction
> is catalyzed by an enzyme, hydrogenase. But simultaneously, there is a
> breakdown of proteins. It appears that the alga is recycling its proteins to
> get sulphur, so that the building blocks necessary for survival can be made.
>
> The beauty of it is that the alga has this ability all along, which no
> genetic engineering could create, and no genetic engineer has even thought
> of attempting to create.  All that was needed was to alter the environment.
> The rate of production is still modest, about 2 millilitres per hour per
> litre of culture, which the researchers are confident of increasing up to
> 10-fold.The process is also reversible, so that the alga can be alternated
> through phases of photosynthesis and hydrogen production several times.
> Dr. Melis is one of the life science professors involved in the deal whereby
> the biotech giant Novartis effectively bought the department for US 50
> million over five years. "But I am really the bottom of the pile", he said
> modestly when I met him in his laboratory, for he was not a genetic engineer
> and did not believe in genetic engineering. Furthermore, Novartis will get
> no right to exploit his research, for it is supported by the Department of
> Energy, which has insisted his research is not part of the Novartis deal. As
> of the beginning of March when I met him, he has had lots of interest from
> companies that grow algae, but not yet from the petrol companies.
> This is a prime example of the kind of science that can really provide safe,
> environmentally friendly and sustainable technologies. It also shows how
> rewarding it is to work with the organism, whose natural potential is far
> greater than can be imagined by reductionist, narrowly focussed genetic
> engineers.
> Reference: Melis, A., Zhang, L., Forestier, M., Ghirardi, M.L. and Seibert,
> M. (2000). Sustained photobiological hydrogen gas production upon reversible
> inactivation of oxygen evolution in the green alga Chlamydomonas
> reinhardtii. Plant Physiology 122, 127-135.
>
> Mae-Wan Ho
> Director, Institute of Science in Society
> <www.i-sis.org>
> c/oBiology Department
> Open University
> Walton Hall Milton Keynes
> MK7 6AA UK
> tel:44-1908-653113
> fax:44-1908-654167
>
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