Newly Engineered Organism Produces High Levels of Isobutanol

Photosynthetic organisms use solar energy to generate reducing equivalents and incorporate atmospheric CO2 into organic molecules.

The Science

DOE-funded researchers from UCLA and UC Davis have engineered a cyanobacterium, Synechococcus elongatus, to convert carbon dioxide into isobutanol (a good gasoline substitute) and isobutyraldehyde using sunlight. One gene from a bacterium commonly used to make cheese and three genes from two common laboratory bacteria were spliced into S. elongates, enabling it to synthesize these biofuels. The conversion capabilities of the re-engineered microbe compare very favorably with bacterial production of hydrogen and ethanol, and algal production of biodiesel. The “contaminating” isobutyraldehyde has a high vapor pressure and low boiling temperature so it should be possible to remove continuously with minimal energy input during fermentation. It can also be easily converted to isobutanol. Subsequent purification is also relatively easy, and the isobutyraldehyde concentration in the production medium can remain low.


Atsumi, S., W. Higashide, and J. C. Liao. 2009. “Direct Photosynthetic Recycling of Carbon Dioxide to Isobutyraldehyde,” Nature Biotechnology 27. DOI:10.1038/nbt.1586.