Optimisation of fermentation conditions for the production of soluble and active tumour necrosis factor α in Escherichia coli

During the past decades, the pharmaceutical industry has been undergoing a major transformation from the production of small molecules to biologics. In 2016, the market for biological products is estimated to reach $210 billion, 40% being produced using microbial platforms (Walsh, 2014). From the plethora of possible microbial hosts, Escherichia coli remains the most widely used and cost-effective “microbial factory” for recombinant protein production.

From a commercial point of view, higher production efficiencies and lower cost have become essential pre-requisites for the development of economically viable processes. However, it is not uncommon that high production of recombinant proteins often leads to stress-induced protein misfolding. Protein misfolding often results in proteolytic degradation or protein aggregation and accumulation of the protein in inclusion bodies (IBs). Optimisation of fermentation conditions to decrease cell stress has been shown to favour the accumulation of soluble and active recombinant proteins (Baneyx and Mujacic, 2004).

Using recombinant human tumour necrosis factor α (rhTNFα) as a model protein, we will discuss how the optimisation of the fermentation conditions can favour the accumulation of correctly folded recombinant proteins. The expression and production of rhTNFα was directed by the arabinose-inducible T7 expression system, using E. coli BL21 as a host strain. Optimisation of the cultivation temperature, inducer concentration and induction point allowed a yield of 3.5 g L^-1 of soluble and active rhTNFα. The main goal of this project is the evaluation and integration of fermentation conditions that allows the design of platforms for recombinant protein production.