Implementation of a Reductive Route of One-Carbon Assimilation in Escherichia coli through Directed Evolution
Abstract
Endowing biotechnological platform organisms
with new carbon assimilation pathways is a key challenge for
industrial biotechnology. Here we report progress toward the
construction of formatotrophic Escherichia coli strains. Glycine
and serine, universal precursors of one-carbon compounds
oxidized during heterotrophic growth, are produced from
formate and CO2 through a reductive route. An adaptive
evolution strategy was applied to optimize the enzymatic steps of
this route in appropriate selection strains. Metabolic labeling
experiments with 13C-formate confirm the redirected carbonflow.
These results demonstrate the high plasticity of the central
carbon metabolism of E. coli and the applicative potential of
directed evolution for implementing synthetic pathways in
microorganisms.