Researchers
at Washington State University have discovered a new type of cooperative
photosynthesis that could be used in engineering microbial communities for
waste treatment and bioenergy production.
Prosthecochloris
aestaurii,
a green-tinged, plant-like microbe, comes from the extreme environment of Hot
Lake, a high salinity lake in northern Okanogan County near Oroville, Wash.
Discovered and identified a few years ago by researchers at the U.S. Department
of Energy's Pacific Northwest National Laboratory and Southern Illinois
University, the bacterium is able to photosynthesize, using sunlight along with
elemental sulfur or hydrogen sulfide to grow.
The
researchers noticed that P. aestuarii
tended to gather around a carbon electrode, an electricity conductor that they
were operating in Hot Lake. The researchers isolated and grew P. aestuarii and determined that,
similar to the way half of a battery works, the bacterium is able to grab
electrons from a solid electrode and use them for photosynthesis. The
pink-colored Geobacter sulfurreducens
meanwhile, is known for its ability to convert waste organic matter to
electricity in microbial fuel cells. The bacterium is also used in
environmental cleanup.
G.
sulfurreducens,
like animals and humans, can't photosynthesize. It consumes organic compounds,
such as acetate, and "breathes" out carbon dioxide.
The
bacterium is known for its ability to donate electrons to a solid electrode. As
it consumes acetate, it generates electrons, which can be collected as
electricity.
The
researchers found that P. aestuarii
could accept electrons generated from G. sulfurreducens and use them in a new
type of anaerobic photosynthesis never before seen. Similar to how a battery or
fuel cell works, the bacteria transfer electrons. They feed off each other to
grow under conditions in which neither could grow independently.
From
an ecological perspective, this new form of metabolism may play an important
role in carbon cycling in oxygen free zones of poorly mixed freshwater lakes.
It may also present new possibilities for engineering microbial communities for
waste treatment and bioenergy production.
For
further details see:
Posted by Dr. Tim Sandle