Sumario: |
Furan aldehydes and phenolic compounds generated during biomass pretreatment can
inhibit fermentation for biofuel production. Efflux pumps actively transport small molecules out
of cells, thus sustaining normal microbial metabolism. Pseudomonas putida has outstanding
tolerance to butanol and other small molecules, and we hypothesize that its efflux pump could
play essential roles for such robustness. Here, we overexpressed efflux pump genes from P.
putida to enhance tolerance of hyper-butanol producing Clostridium
saccharoperbutylacetonicum to fermentation inhibitors. Interestingly, overexpression of the
whole unit resulted in decreased tolerance, while overexpression of the subunit (srpB) alone
exerted significant enhanced robustness of the strain. Compared to the control, the engineered
strain had enhanced capability to grow in media containing 17% more furfural or 50% more
ferulic acid, and produced ~14 g/L butanol (comparable to fermentation under regular conditions
without inhibitors). This study provided valuable reference for boosting microbial robustness
towards efficient biofuel production from lignocellulosic materials.
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