Stabilizing overproduction of chemicals in E. coli through dynamic control of metabolic pathways

Overproduction of chemicals is a burden for bacteria. To balance overproduction and growth, a doubly-regulated glycerol biosynthetic pathway from yeast was introduced to E. coli. In this system, the arabinose-inducible promoter (pBAD) allows external control of glycerol-gene expression, and an addition of binding sites of native transcription factors (e.g. Cra) coupled expression to gene regulation of the host. Under high levels of external inducer (arabinose), the doubly-regulated system stabilized growth and doubled glycerol production. The single-regulated system, without transcription factor binding sites, resulted in cell death at high induction. Metabolome and proteome data revealed functioning of this doubly-regulated expression system.