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Identification of Efflux Pumps to Improve Tolerance to Toxic or Tnhibitory Biofuel, Biochemical Metabolities or Compounds from Deconstructed Ligno-Cellulosic Biomass


The JBEI has developed a method for providing industrial host microbes with resistance to valuable but potentially toxic molecules, such as solvents and fuel-like compounds. Providing such tolerance is a crucial step in engineering organisms to produce desirable substances. The scientists used efflux pumps to confer resistance on E. coli and developed a library of the most effective pumps for protection against several compounds, such as geraniol, limonene, pinene, and farnesyl hexanoate. These compounds represent biogasoline, biodiesel, and biojetfuel candidates. Moreover, the method for deriving this library is applicable to determining the most effective pumps for any given host and target compound. As metabolic engineering increases the biological production titers of compounds, there is a growing need to overcome limitations posed by each compounds toxicity, inhibition of cell growth, and intracellular feedback inhibition (i.e., the slowing of production by accumulated product). Until now, these problems have been addressed primarily through combinatorial approaches, such as adaptation, genome shuffling, and random mutatgenesis. These techniques may work under certain settings but are often not transferrable to other hosts or target compounds, because they do not identify the mechanism of the resistance. On the other hand, the JBEI technology uses a known, transferrable mechanisman efflux pumpto optimize the tolerance of various hosts to any compound of interest. In several cases where the target compound is highly water immiscible, successful export of the compound from the cell can also improve product extraction from the culture.
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