title: Trade-Offs in Improving Biofuel Tolerance Using Combinations of Efflux Pumps.
abstract: Microbes can be engineered to produce next-generation biofuels; however, the accumulation of toxic biofuels can limit yields. Previous studies have shown that efflux pumps can increase biofuel tolerance and improve production. Here, we asked whether expressing multiple pumps in combination could further increase biofuel tolerance. Pump overexpression inhibits cell growth, suggesting a trade-off between biofuel and pump toxicity. With multiple pumps, it is unclear how the fitness landscape is impacted. To address this, we measured tolerance of Escherichia coli to the biojet fuel precursor α-pinene in one-pump and two-pump strains. To support our experiments, we developed a mathematical model describing toxicity due to biofuel and overexpression of pumps. We found that data from one-pump strains can accurately predict the performance of two-pump strains. This result suggests that it may be possible to dramatically reduce the number of experiments required for characterizing the effects of combined biofuel tolerance mechanisms.
authors.affiliation: School of Engineering, University of Vermont , Burlington, Vermont 05405, United States.
authors.forename: William J
authors.initials: WJ
authors.lastname: Turner
authors.affiliation: School of Engineering, University of Vermont , Burlington, Vermont 05405, United States.
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Dunlop
mesh_terms: D000081008:Bicyclic Monoterpenes; D057005:Bioengineering / Q000191:economics* / Q000379:methods*; D056804:Biofuels / Q000633:toxicity*; D003362:Cost-Benefit Analysis; D004926:Escherichia coli / Q000187:drug effects; D039821:Monoterpenes / Q000633:toxicity
chemical_list: D000081008:Bicyclic Monoterpenes; D056804:Biofuels; D039821:Monoterpenes; C005451:alpha-pinene
keywords: biofuel tolerance; biofuel toxicity; cost-benefit; efflux pump; trade-off