BL21 Star (DE3) Escherichia coli Strains

BL21 Star (DE3) Escherichia coli strains are specialized derivatives of Escherichia coli optimized for high‑level recombinant protein expression in research and industrial applications. These strains are engineered to support expression systems driven by the T7 promoter, making them ideal hosts for proteins cloned into pET and similar vectors.

● Enhanced Protein Production : BL21 Star (DE3) harbors a mutation in the RNase E gene (rne131) which reduces degradation of mRNA transcripts. This increases mRNA stability and leads to higher protein yields compared with standard BL21(DE3) strains, especially for non‑toxic proteins.

● T7 Expression System Compatibility : The DE3 designation indicates the strain contains a λDE3 prophage that encodes T7 RNA polymerase under control of a lacUV5 promoter. Upon induction (e.g., with IPTG), T7 RNA polymerase drives strong expression of cloned genes under a T7 promoter.

● Reduced Proteolysis : BL21 strains (including Star derivatives) are derived from the E. coli B lineage and lack key proteases such as Lon and OmpT. This reduces degradation of expressed proteins, improving overall yield and stability.

● Robust Growth Characteristics :These strains grow well under standard laboratory conditions and support high‑level expression without excessive acetate accumulation or growth inhibition, which can be advantageous for scaling cultures.

Escherichia coli BL21 Star (DE3) strains are engineered bacterial hosts optimized for robust and efficient expression of recombinant proteins under the control of T7 promoter‑based systems. They feature enhanced mRNA stability, reduced protease activity, and strong induction characteristics, making them a top choice for many protein production workflows in life sciences and biotechnology.

• Recombinant protein expression for research and development.
• Production of proteins for biochemical assays and structural studies.
• Expression of enzymes, antibody fragments, and other heterologous proteins.
• Preparative protein expression in industrial and academic laboratories.