The four main in vivo expression systems used by PEF are:

  • Bacteria
  • Yeast
  • Insect cell/Baculovirus Expression Vector System (BEVS)
  • Mammalian cell

PEF also offers expression services using the in vitro cell-free Leishmania tarentolae system for rapid protein production and analysis. To view our list of available cell strains/cell lines, please visit our resource centre.

Each in vivo system has benefits and drawbacks with respect to their capacity for recombinant protein production. The figure below illustrates some of the key advantages and disadvantages of the four major systems used in PEF:

Protein Expression Systems

Small-scale Expression Screen

PEF offers a small-scale expression screen in each system that is designed to test different expression parameters to find an optimal condition. Users can request specific conditions or allow PEF to suggest a set of conditions to use in each screen. For small-scale expression services, please contact us for a quote.

Large-scale Expression

PEF offers large-scale expression in bacteria, yeast, insect and mammalian cell systems. Culture volumes from 400 mL to 10 L are available in shake flask and from 2 L to 20 L in a stirred-tank bioreactor or up to 25 L in a Wave bioreactor. For large-scale expression services, please contact us for a quote.


PEF offers training for staff and students in all aspects of recombinant protein production. If you would like to enquire about training in any of the expression systems offered by PEF, please contact us.

For an overview of the services provided by PEF, please visit the PEF production pipeline.

1. Bacteria Services

E. coli is frequently the first expression host chosen for the production of a recombinant protein, owing to the rapid, cheap and technically straight-forward culturing associated with its use. Services available from PEF include:

  • Developing an effective strategy for molecular cloning and bacterial expression
  • Custom or high throughput cloning into a range of bacterial expression vectors, including:
    • pOPIN
    • pET
    • pGEX
  • Transformation into a wide range of E. coli expression strains, including:
    • BL21 (DE3)
    • BL21 (DE3) pLysS
    • BL21 (DE3) CodonPlus-RIL
    • BL21 (DE3) Star
    • Rosetta (DE3) pLysS
    • Rosetta 2 (DE3)
    • Arctic Express (DE3) pLysS
    • Tuner (DE3)
    • Shuffle T7 Express
  • Small-scale expression screening to determine optimal expression conditions
  • Large-scale expression in shake flasks and stirred-tank bioreactors

In addition to regular communication updates throughout your project, we provide a highly detailed report on project completion. To view a sample report, please download the pdf here.

For all bacterial expression services, including customised cloning and bioreactor-scale expression, please contact us for a quote.