Investigation of induction conditions for recombinant L-Threonine-Aldolase expression in E. coli

Abstract

Many approaches have been investigated regarding recombinant protein production in E. coli, the most prominent being a pET plasmid in the strain E. coli BL21(DE3) with the target protein under control of the T7 promoter. However, other strains may be required for the expression of a target protein. The Austrian company Valanx Biotech GmbH approached the IBD group of TU Wien to find a production process for recombinant L-Threonine Aldolase (rLTA) in E. coli BL21 with the target gene under control of the phage-derived T5 promoter. This process would then be implemented in a scale-up experiment. Thus, different conditions for the induction of rLTA expression were investigated in this particular expression system. It was hypothesized that active soluble rLTA expression and the productivity of the expression system for this protein is dependent on (1) the type of inducer, (2) the temperature during induction and (3) the substrate feeding rate translating into a specific growth rate during induction. It was shown that the inducer lactose with a specific growth rate of μ = 0.05 h-1 and an induction temperature of 30 °C yielded the most promising results with respect to active soluble rLTA production.