High-throughput clone screening and upstream process optimization for recombinant therapeutic peptide expression: biosimilar teriparatide (PTH-34): a case study

The study focuses on high-throughput optimization of the upstream process for the expression of biosimilar teriparatide using a microfermenter platform. Key upstream parameters, including <i>E. coli</i> host strains, growth media, and induction strategies, were systematically investigated to enhance the peptide expression. A design of experiments (DoE) approach was employed to assess the effects of individual parameters and their interactions on biomass yield and biosimilar peptide expression. Five <i>E. coli</i> strains- BL21 (DE3), Lemo 21^™ (DE3), Rosetta^™ (DE3), Origami^™ 2, and Shuffle^® T7 (DE3) were evaluated, with BL21 (DE3) and Origami^™ 2 exhibiting the highest growth rates of 0.529 ± 0.05 h^-1 and 0.242 ± 0.05 h^-1, respectively. Induction using galactose was identified as the most effective method for enhancing teriparatide expression by minimizing metabolic stress on host cells. A comparative analysis between microfermenter and shake flask experiments yields consistent results for biomass and biosimilar teriparatide expression, validating the scalability and efficiency of the optimized process. Upon scale-up to a 1-L bioreactor using optimized parameters, <i>E. coli</i> BL21 (DE3) achieved a biomass yield of 67.9 ± 1.0 g/L and 12.0 ± 0.6 g/L of inclusion bodies. These findings highlight the potential of the DoE-based microfermenter for cost-effective and scalable peptide production.