Industrializing a bacterial strain for L-serine production through translation initiation optimization

Turning a proof-of-concept synthetic biology design into a robust, high performing cell factory is a major time and money consuming task, which severely limits the growth of the white biotechnology sector. Here, we extend the use of tunable antibiotic resistance markers for synthetic evolution (TARSyn), a workflow for screening translation initiation region (TIR) libraries with antibiotic selection, to generic pathway engineering, and transform a proof-of-concept synbio design into a process that performs at industrially relevant levels. Using a combination of rational design and adaptive evolution, we recently engineered a high-performing bacterial strain for production of the important building block biochemical L-serine, based on two high-copy pET vectors facilitating expression of the serine biosynthetic genes serA, serC and serB from three independent transcriptional units. Here, we prepare the bacterial strain for industrial scale up by transferring and reconfiguring the three genes into an operon e...