S124: Antibiotic-free selection in E. coli: a new gold standard for safety, productivity and genetic stability

The increasing regulatory requirements to which biological agents are subjected will have a great impact in the field of industrial protein expression and production. The expectation is that in a near future, there may be “zero tolerance” towards antibiotic-based selection in production systems. Besides the antibiotic itself, the antibiotic resistance gene is an important consideration. The complete absence of antibiotic-resistance gene being the only way to ensure that there is no propagation in the environment or transfer of resistance to pathogenic strains.

We have proposed and validated, at both laboratory and pre-industrial scale, a general strategy combining plasmid stabilisation and antibiotic-free selection. The proposed host/vector system, obtained through combined genomic and plasmid engineering is completely devoid of antibiotic resistance gene and brings the additional advantage of improving recombinant protein expression and/or plasmid recovery. A marked increase in genetic stability, over high stress fermentation conditions has been demonstrated.