http://www.sciencedaily.com/releases/2008/07/080710094033.htm

Can Microorganisms Be A Solution To The World's Energy Problems?

Rendered image of bacteria. Microorganisms once reigned supreme on the
Earth, thriving by filling every nook and cranny of the environment
billions of years before humans first arrived on the scene. (Credit:
iStockphoto/Henrik Jonsson)ScienceDaily (July 11, 2008) —
Microorganisms once reigned supreme on the Earth, thriving by filling
every nook and cranny of the environment billions of years before
humans first arrived on the scene. Now, this ability of microorganisms
to grow from an almost infinite variety of food sources may play a
significant role in bailing out society from its current energy
crisis, according to the Biodesign Institute's Bruce Rittmann, Rosa
Krajmalnik-Brown, and Rolf Halden.

In a new issue on "microbial ecology and sustainable energy" in the
journal Nature Reviews Microbiology, the Biodesign researchers outline
paths where bacteria are the best hope in producing renewable energy
in large quantities without damaging the environment or competing with
our food supply.

Two distinct, but complementary approaches will be needed. The first
is to use microbes to convert biomass to useful energy. Different
microorganisms can grow without oxygen to take this abundant organic
matter and convert it to useful forms of energy such as methane,
hydrogen, or even electricity. The second uses bacteria or algae that
can capture sunlight to produce new biomass that can be turned into
liquid fuels, like biodiesel, or converted by other microorganisms to
useful energy. Both approaches currently are intensive areas of
biofuel research at the Biodesign Institute, which has a joint project
with petroleum giant BP to harvest photosynthetic bacteria to produce
renewable liquid fuels, such as biodiesel.

What is it about bacteria that make them an attractive tool for a
bioenergy researcher? Consider that one species of bacteria, the human
gut bacterium E. coli, has become the workhorse of the multi-trillion
dollar global biotech industry. Might other unearthed microbial
treasures have the same potential in bioenergy applications?

The Biodesign team, in their Nature Review Microbiology perspective
article, outlines the prospects for such applications. They believe
the future of microbial bioenergy is brightened by recent advancements
in genome technologies and other molecular-biology techniques.

Unlike the E. coli situation, using just one species may not work well
for bioenergy, since, in nature, bacteria do not grow in isolation. In
other words, no bacterium is an island. The very biodiversity that
fills the Earth with bacteria and offers great bioenergy potential
also presents a challenge for engineers. Even if one picks the ideal
"bug," growing, maintaining, and optimizing conditions for its use in
bioenergy applications remains a daunting challenge in terms of
scalability and reliability.

"Microbial communities that are used to harvest energy must be
resilient to fluctuations in environmental conditions, variations in
nutrient and energy inputs and intrusion by microbial invaders that
might consume the desired energy product," say the authors. The key to
large-scale success in microbial bioenergy is managing the microbial
community so that that the community delivers the desired bioenergy
product reliably and at high rate.

In the absence of these molecular techniques, the authors state, our
understanding of methanogenic communities progressed through slow,
incremental advances over several decades. Today, society cannot wait
decades for new bioenergy sources. Fortunately, an array of pre-
genomic, genomic, and post-genomic tools is available to understand
microorganisms involved in bioenergy production. Taking full advantage
of these tools will greatly speed up scientific and technological
advances, which is what society most needs.

Genomics provides the base sequence of the entire DNA in an organism,
and the complete genome reveals all the possible biological reactions
that a microorganism can carry out. In the past, complete genomes were
only obtained for those microorganisms that could be isolated into
pure culture, but it is now possible to sequence the genomes of
uncultivated microorganisms using metagenomics.

To date, approximately 75 genomes are available from microorganisms
that have a role in bioenergy production. These include 21 genomes
from methane producing archaea, 24 genomes from bacteria that can
produce hydrogen or electricity, and 30 genomes from cyanobacteria
that are potential biodiesel producers. At least half of the completed
microbial genomes that are relevant to bioenergy were released in the
past 2 years, and more than 80 bioenergy-related genomes are currently
being sequenced.

A great example is the Biodesign Institute's biofuel bacterium,
Synechocystis sp. PCC 6803, the first bioenergy-relevant microorganism
to be sequenced; its genome was released in 1995. This photosynthetic
bacterium features membranes with high lipid (i.e., oil) content,
which makes it an excellent biodiesel candidate.

The growing pool of genomic information provides molecular targets
that support pre-genomic and post-genomic investigations, both of
which provide essential information on what microorganisms are present
in the community and what metabolic reactions they are carrying out.
With genomics combined with high-throughput DNA sequencing and
proteomics, our understanding of bioenergy-producing microorganisms
should surge.

Because success with microbial bioenergy demands in-depth knowledge of
the complex microbial communities that normally develop, a wide range
of pre-genomic, genomic, and post-genomic tools is needed. The
Biodesign team has unique expertise on using each kind of tool, and
it's perspective article provides needed information about these tools
and how they can be used to unravel the structures and functions of
microbial communities involved in renewable bioenergy.

The authors conclude, "Information from these tools, when properly
integrated with advanced engineering tools and material, should
accelerate the rate at which microbial bioenergy processes can be
converted from the realm of intriguing science to real world
practice."

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Journal reference:

Bruce E. Rittmann, Rosa Krajmalnik-Brown & Rolf U. Halden. Pre-
genomic, genomic and post-genomic study of microbial communities
involved in bioenergy. Nature Reviews Microbiology, July 7, 2008 DOI:
10.1038/nrmicro1939

Adapted from materials provided by Arizona State University, via
EurekAlert!, a service of AAAS.

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Arizona State University (2008, July 11). Can Microorganisms Be A
Solution To The World's Energy Problems?. ScienceDaily. Retrieved July
16, 2008, from http://www.sciencedaily.com­ /releases/
2008/07/080710094033.htm