Saving biofuels' magic bugs from their own toxins

May 13, 2011 |

In California, the Lawrence Berkeley National Laboratory announced that Joint BioEnergy Institute  researchers have found a way to help microbes survive the toxicity caused by the very compounds that they secrete in order to produce biofuels.  Many of the best candidate compounds for advanced biofuels are toxic to microbes, which presents a “production versus survival” conundrum.

Researchers at the DOE’s JBEI have provided a solution to this problem by developing a library of microbial efflux pumps that were shown to significantly reduce the toxicity of seven representative biofuels in engineered strains of Escherichia coli.  Microbes employ various strategies for addressing cell toxicity but perhaps the most effective are efflux pumps, proteins in the cytoplasmic membrane of cells whose function is to transport toxic substances out of the cell.

However, to date very few of these have been characterized for efficacy against biofuel like compounds.  After establishing a large library of such pumps, the researchers ran a series of survival competitions.  The two microbial efflux pumps that performed best were the native E. coli pump AcrAB and a previously uncharacterized pump from a marine microbe Alcanivorax borkumensis.

The researchers have begun evaluating microbial efflux pumps for other important compounds as well as inhibitors present in the carbon source from lignocellulose. They are also looking to improve the A. borkumensis pump and other high performers in their current library, and to optimize the systems by which pump genes are expressed in engineered biofuel-producing microbial strains.

Category: Research

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