Proteins are among the most abundant biomolecules on earth. They are usually considered as a food source, however, James Liao and colleagues, University of California, Los Angeles, USA, have shown that certain proteins could be used as an alternative fuel source. They applied metabolic engineering to generate Escherichia coli that could deaminate protein hydrolysates. The modified cells could then convert proteins to C4 and C5 alcohols at 56 % of the theoretical yield. Up to 4,035 mg/L of alcohols could be produced in this manner.

The team calculates that the culture area needed to produce 60 billion gallons of biofuels (30 % of the United States’ current transportation fuel) based on the new technology could be as little as 24,600 km² — equivalent to 1.9 % of the agricultural land in the US — compared with approx. 45,000 km² required to generate the same amount of bioethanol from corn.

• Conversion of proteins into biofuels by engineering nitrogen flux
  Y.-X. Huo, K. M. Cho, J. G. Lafontaine Rivera, E. Monte, C. R. Shen, Y. Yan, J. C. Liao,
  Nat. Biotech. 2011.
  DOI: 10.1038/nbt.1789
• Biofuels in the U.S. Transportation Sector, US Energy Information Adminstration, February 2007