Cyanobacteria are a promising source of biofuels. They have
higher growth rates and greater solar energy capture efficiency than
multi-cellular plants. Traditional downstream recovery of the cell membrane
lipids from cyanobacteria, however, typically requires cell lysis followed by
solvent extraction. This can account for 70-80% of the cost of biofuel
production. If these operations could be eliminated, it would substantially
reduce the cost of producing biofuels from cyanobacteria.
Researchers at the Biodesign Institute of Arizona State
University have engineered a strain of the cyanobacterium, Synechocystis sp.
PCC6803, so as to die in a controlled fashion when CO2 is removed from the
growth environment. Under low CO2 conditions, in as little as 30 minutes,
inducible promoters up-regulate the synthesis of lipolytic enzymes. These
convert membrane lipids into free fatty acids, which are more readily processed
into biofuel than the membrane lipids and can easily be collected as they are
released when the membranes disintegrate and the cells collapse.
This technology has the potential to significantly reduce
the cost of algal biofuel production, both by eliminating physical cell lysis
and solvent extraction, and by producing free fatty acids rather than the
diacylglycerols present in membrane lipids.
This technology can be paired with other cyanobacterial
genetic engineering technologies, and has produced yields of nearly 4x10-11
mg/cell.
Potential Applications
- Algal biofuel production
- Pairing with other genetic engineered cyanobacterial
technologies, such as producing and excreting biodiesel-chain length neutral
lipids in lieu of increasing biomass (AzTE Cases # M9-017 and
M10-180)
Benefits and Advantages
- Less expensive than physical cell lysis and solvent
extraction of membrane lipids
- Produces free fatty acids, which are more readily
processed into biofuel than diacylglycerols present in membrane lipids
- Amenable to combination with other genetic engineered
cyanobacterial technologies for even greater productivity
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For more information about the inventor(s) and their
research, please see
Dr.
Curtiss' directory webpage
Dr.
Curtiss' departmental webpage
