Thermo Fisher Scientific MultiShot StripWell BL21 Star (DE3) Competent Cells

Invitrogen™ MultiShot™ StripWell BL21 Star™ (DE3) Competent Cells

MultiShot StripWell BL21 Star (DE3) chemically competent E. coli cells are cloning competent cells designed for applications that require high-level expression of non-toxic recombinant proteins from low copy number, T7 promoter-based expression systems.
These cells carry the λDE3 lysogen containing the T7 RNA polymerase gene under control of the _lac_UV5 promoter and are pre-aliquoted in a rack containing 12 strips of 8 wells to increase productivity for high-throughput bacterial transformations.

Enhanced Expression of Non-toxic Recombinant Proteins

The BL21 (DE3) E. coli strain is widely used for recombinant protein production in research and industrial applications. IPTG induction activates the T7 RNA polymerase cascade, which transcribes target genes under the T7 promoter.
Derived from the E. coli B strain, BL21 (DE3) lacks the lon protease and outer membrane protease OmpT, minimizing degradation of heterologous proteins. The strain also exhibits fast growth in minimal medium, reduced acetate production in high-glucose conditions, and high cell density capability.

Enhanced mRNA Stability

BL21 Star (DE3) Competent Cells include an RNaseE gene mutation (_rne_131) that reduces endogenous RNase levels and mRNA degradation, increasing transcript stability and protein yield.
BL21 Star strains show higher basal expression of heterologous genes than BL21 (DE3), making them ideal for non-toxic protein expression. For toxic proteins, BL21-AI is recommended.

Key Features of One Shot BL21 Star (DE3) Competent Cells

• Transformation efficiency >1 × 10⁷ cfu/μg plasmid DNA
• Deficiency in lon and OmpT proteases reduces recombinant protein degradation
• Optimized for low copy number, T7 promoter-based plasmids
• _rne_131 mutation enhances mRNA stability
• _hsd_S mutation allows efficient transformation of unmethylated DNA
• Fast growth and high cell density in minimal media

MultiShot StripWell Flexible Format

Each StripWell of eight connected tubes offers single-use convenience similar to One Shot tubes. All transformation steps—from DNA addition to plating—can be performed in the same tube, saving time and reducing contamination risks.
After DNA addition, cells can be heat-shocked at 42°C directly in the tube.
Strips can be easily cut for single-tube transformations, preventing cell waste and freeze-thaw efficiency loss.

Benefits of MultiShot StripWell Format

• Increased productivity for high-throughput experiments
• Maximal flexibility—transform 1 to 96 tubes from the StripWell rack
• Convenient workflow—add DNA, heat shock, and recover in the same tube

Genotype

F– _omp_T _hsd_SB (rB–, mB–) _gal dcm rne_131 (DE3)

Additional Information

Thermo Fisher Scientific offers various E. coli strains and formats of chemically and electrocompetent cells to meet transformation needs.
Explore bacterial growth media and protein expression systems optimized for E. coli.

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