May 14, 2009
Microbe makes most of light
the light-harvesting components of light-starved bacteria and you've
got a model for super-efficient solar cells.
Green sulfur bacteria are the most efficient light-harvesting
organisms. They survive by photosynthesizing tiny amounts of light.
Their light-absorbing antenna -- chlorosomes -- are much larger than
light-harvesting components of other photosynthetic microorganisms
The combination of nuclear magnetic resonance and cryogenic
electron microscopy provided enough information to reveal the green
sulfur bacteria's secret: the antenna are made of as many as 250,000
pigment molecules -- bacteriochlorophyll -- that assemble themselves
into nested nanotubes. Light-harvesting components of other photosynthetic
organisms tend, instead, to be held together with protein molecules.
The chlorophyll molecules pair up head-to-head with tails
extending outward. Many thousands of pairs form a spiral pattern to
make the nanotubes. The spiral is key to the bacteria's efficiency;
the offset pattern allows the molecules to channel and rapidly transmit
energy absorbed from photons rather than letting the energy wander
from molecule to molecule.
Chlorosomes' simple structure and self-assembly could inspire
methods of making highly-efficient and inexpensive solar cells.
syn-anti bacteriochlorophylls form concentric helical nanotubes in
Proceedings of the National Academy of Sciences, published
online May 12, 2009
J. M. de Groot
Related stories and briefs:
proteins boost solar concentrators -- related research
drives solar fuel cell -- related research
Back to ERN home
Energy-related books and products