Review of approaches to engineer microbes to produce advanced biofuels
13 November 2010
Dr. Larry Wackett, Distinguished McKnight University Professor, Department of Biochemistry, University of Minnesota, has a paper in press in the journal Current Opinion in Biotechnology reviewing approaches to engineering microbes to produce advanced biofuels, including renewable hydrocarbons.
Wackett is also lead investigator in a $2.2-million ARPA-E funded effort to use an innovative artificial symbiotic colony of photosynthetic bacteria with Shewanella, a hydrocarbon-producing bacteria to produce liquid transportation fuels. The photosynthetic organisms will use sunlight to convert CO2 to sugar, which the Shewanella will then convert to bio-hydrocarbons. (Earlier post.)
The current biofuels landscape is chaotic. It is controlled by the rules imposed by economic forces and driven by the necessity of finding new sources of energy, particularly motor fuels. The need is bringing forth great creativity in uncovering new candidate fuel molecules that can be made via metabolic engineering. These next generation fuels include long-chain alcohols, terpenoid hydrocarbons, and diesel-length alkanes.
Renewable fuels contain carbon derived from carbon dioxide. The carbon dioxide is derived directly by a photosynthetic fuel-producing organism(s) or via intermediary biomass polymers that were previously derived from carbon dioxide. To use the latter economically, biomass depolymerization processes must improve and this is a very active area of research. There are competitive approaches with some groups using enzyme based methods and others using chemical catalysts.
With the former, feedstock and end-product toxicity loom as major problems. Advances chiefly rest on the ability to manipulate biological systems. Computational and modular construction approaches are key. For example, novel metabolic networks have been constructed to make long-chain alcohols and hydrocarbons that have superior fuel properties over ethanol. A particularly exciting approach is to implement a direct utilization of solar energy to make a usable fuel. A number of approaches use the components of current biological systems, but re-engineer them for more direct, efficient production of fuels.
—Wackett 2010
Resources
Lawrence P Wackett (2010) Engineering microbes to produce biofuels. Current Opinion in Biotechnology Article in Press doi: 10.1016/j.copbio.2010.10.010
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