Open AccessEngineering microbial biofuel tolerance and export using efflux pumps
Author(s) -
Dunlop Mary J,
Dossani Zain Y,
Szmidt Heather L,
Chu Hou Cheng,
Lee Taek Soon,
Keasling Jay D,
Hadi Masood Z,
Mukhopadhyay Aindrila
Publication year - 2011
Publication title -
molecular systems biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.523
H-Index - 148
ISSN - 1744-4292
DOI - 10.1038/msb.2011.21
Subject(s) - biofuel , metabolic engineering , efflux , isobutanol , biology , microbiology and biotechnology , synthetic biology , biochemical engineering , butanol , production (economics) , computational biology , biochemistry , gene , ethanol , engineering , macroeconomics , economics
Many compounds being considered as candidates for advanced biofuels are toxic to microorganisms. This introduces an undesirable trade‐off when engineering metabolic pathways for biofuel production because the engineered microbes must balance production against survival. Cellular export systems, such as efflux pumps, provide a direct mechanism for reducing biofuel toxicity. To identify novel biofuel pumps, we used bioinformatics to generate a list of all efflux pumps from sequenced bacterial genomes and prioritized a subset of targets for cloning. The resulting library of 43 pumps was heterologously expressed in Escherichia coli , where we tested it against seven representative biofuels. By using a competitive growth assay, we efficiently distinguished pumps that improved survival. For two of the fuels ( n ‐butanol and isopentanol), none of the pumps improved tolerance. For all other fuels, we identified pumps that restored growth in the presence of biofuel. We then tested a beneficial pump directly in a production strain and demonstrated that it improved biofuel yields. Our findings introduce new tools for engineering production strains and utilize the increasingly large database of sequenced genomes.