Isobutanol production freed from biological limits using synthetic biochemistry

Nat Commun. 2020 Aug 27;11(1):4292. doi: 10.1038/s41467-020-18124-1.


Cost competitive conversion of biomass-derived sugars into biofuel will require high yields, high volumetric productivities and high titers. Suitable production parameters are hard to achieve in cell-based systems because of the need to maintain life processes. As a result, next-generation biofuel production in engineered microbes has yet to match the stringent cost targets set by petroleum fuels. Removing the constraints imposed by having to maintain cell viability might facilitate improved production metrics. Here, we report a cell-free system in a bioreactor with continuous product removal that produces isobutanol from glucose at a maximum productivity of 4 g L-1 h-1, a titer of 275 g L-1 and 95% yield over the course of nearly 5 days. These production metrics exceed even the highly developed ethanol fermentation process. Our results suggest that moving beyond cells has the potential to expand what is possible for bio-based chemical production.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acetolactate Synthase / chemistry
  • Acetolactate Synthase / metabolism
  • Adenosine Triphosphate
  • Alcohol Oxidoreductases / genetics
  • Alcohol Oxidoreductases / metabolism
  • Biochemistry / instrumentation
  • Biochemistry / methods*
  • Bioreactors
  • Butanols / metabolism*
  • Cell-Free System
  • Directed Molecular Evolution
  • Enzymes / chemistry
  • Enzymes / genetics
  • Enzymes / metabolism*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Glucose / metabolism
  • Temperature
  • Thermodynamics


  • Butanols
  • Enzymes
  • Escherichia coli Proteins
  • isobutyl alcohol
  • Adenosine Triphosphate
  • Alcohol Oxidoreductases
  • YahK protein, E coli
  • Acetolactate Synthase
  • Glucose