Decoupling Growth and Production by Removing the Origin of Replication from a Bacterial Chromosome

Efficient production
of biochemicals and proteins in cell factories
frequently benefits from a two-stage bioprocess in which growth and
production phases are decoupled. Here, we describe a novel growth
switch based on the permanent removal of the origin of replication
(oriC) from the Escherichia coli chromosome. Without oriC, cells cannot initiate
a new round of replication, and they stop growing while their metabolism
remains active. Our system relies on a serine recombinase from bacteriophage
phiC31 whose expression is controlled by the temperature-sensitive
cI857 repressor from phage lambda. The reporter protein expression
in switched cells continues after cessation of growth, leading to
protein levels up to 5 times higher compared to nonswitching cells.
Switching induces a unique physiological state that is different from
both normal exponential and stationary phases. The switched cells
remain in this state even when not growing, retain their protein synthesis
capacity, and do not induce proteins associated with the stationary
phase. Our switcher technology is potentially useful for a range of
products and applicable in many bacterial species for decoupling growth
and production.