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Endotoxin-free ClearColi™ Expression System






Eliminate Endotoxin at the Source

The Gram-negative bacterium E. coli is the workhorse of molecular biology, regularly used as the primary host for DNA cloning and protein production. Arguably the most costly aspect of using E. coli is purifying the products from contaminating Lipopolysaccharide, LPS, also known as endotoxin. A component of the outer-cell membrane of the organism, LPS contaminates all recombinant products made in the organism. Humans are exquisitely sensitive to the lipid A portion of LPS that interacts with TLR4/MD-2 receptors to unleash a toxic immune response. In order to use E. coli produced products in cell-based assays or in vivo, manufacturers must laboriously eliminate essentially all endotoxin from their products to meet established standards.

The ClearColi® Expression System is an E. coli expression host containing genetically modified LPS that does not trigger an endotoxic response in human cells.


Protein Production:

For Protein production RCT has developed ClearColi® BL21(DE3). These ClearColi® strains exhibit slightly slower growth rates than other commercially available expression systems but reach high ODs and express with similar yields a wide variety of proteins that typically express in E. coli.These ClearColi® strains are ideal for:

  • expressing proteins, such as APOA1, for which endotoxin removal is notoriously difficult, for producing proteins
  • screening in cell based assays, particularly immunological assays which are easily contaminated with LPS
  • producing growth factors, chemokines and cytokines used in cell culture.
    For more information on the performance of the ClearColi® strains, please review the poster and application note in Nature Methods.
After minimal purification even the most difficult proteins are largely free of endotoxin.

Plasmid Production:

For Plasmid production RCT has developed ClearColi® K-12. These ClearColi™ strains exhibit near normal growth rates, reach high ODs, and express plasmids with yields similar to DH10B cells.These ClearColi® strains are ideal for mammalian transfection and protein expression eliminating the need for expensive endotoxin-free plasmid prep kits.For additional information, please review the poster. clear-colik-12-plasmid
Plasmid production free from endotoxin contamination.

Purchase ClearColi®:





RCT has partnered with Lucigen to commercialize the ClearColi® Expression Technology. ClearColi® Kits and strains can be purchased from Lucigen.


RCT has developed the technology under broad patent rights covering the ClearColi® Expression System strains acquired from the University of Michigan and development programs with FZB (Forshungzentrum Borstel).

  • Ron Woodard, Ph.D., University of Michigan
  • Uwe Mamat, Ph.D., Forshungzentrum Borstel


Specific commercial host strains have been created for out-licensing to industry. These are the subject of additional intellectual property protection. With the purchase of a kit from Lucigen users receive a limited use license providing a limited opportunity to evaluate the strains. RCT is seeking partners to apply and commercialize the ClearColi™ Expression System.

Related Website:


RCT Contact

Brad Morie