Bacterial Expression

Bacteria is the most popular host of choice for the expression of many proteins as production of heterologous protein in bacteria is easy, time-saving and cost-efficient. A large number of bacterial expression plasmids are also available and suitable for a wide variety of needs. Most commonly used bacterial hosts for protein production include E.coli and Bacillus subtilis.

Advantages:

• Simple physiology
• Short generation timeline, as bacteria grow and multiply rapidly
• Tight control of gene expression with the highest yield compared to other systems - up to 10 % of mass
• Broad range of expression levels using different inducer concentrations
• Active at low temperature (16ºC) and low sensitivity to media formulation
• Availability of vectors with protein fusion tags for purification using low cost affinity supports
• Cost effective and scalable bioprocess engineering
• Higher rate of success in obtaining soluble proteins

Disadvantages:

• Activity. The expressed proteins often do not fold properly, resulting in are biologically inactive.
• Toxicity. The synthesized proteins are often toxic to bacteria, preventing the cell cultures from reaching high densities. A solution to this problem is to incorporate an inducible promoter, which may be turned on to transcribe the inserted gene after the culture has been grown.
• Modification. Lack of enzymes responsible for post-translational modifications (effect on function of proteins), e.g. if the protein to be expressed is a glycoprotein, there is no apparatus in the bacterium to attach the necessary sugar residues. In this case, mammalian cell expression system is the best choice.

Applications:

• Laboratory and large scale recombinant protein expression/purification: optimization of host, expression systems, and downstream processing with the use of our genetic technology.
• Whole cell biocatalysis: stable assemblage of metabolic pathways.
• Programming therapeutic bacteria expression: antigen expression and display in attenuated pathogenic bacteria.
• Expression of heteromultimeric proteins.

Figure 1. High throughput screening process for bacterial expression systems

Please see Creative Biostructure’s cell-free and cell-based expression services.

Reference:

1. Rachel Chen. Bacterial expression systems for recombinant protein production: E. coli and beyond. Biotechnology Advances. Volume 30, Issue 5, September–October 2012, Pages 1102–1107
2. Germán L. Rosano and Eduardo A. Ceccarelli. Recombinant protein expression in Escherichia coli: advances and challenges. Front Microbiol. 2014; 5: 172. doi: 10.3389/fmicb.2014.00172