Product Information

Description

E. coli  BL21 Star (DE3) is designed for applications that require high-level expression of non-toxic recombinant proteins from low copy number, T7 promoter-based expression systems (e.g., pET vectors).

• Contain a genotype that promotes high mRNA stability and protein yield
• Optimized for use with low copy number, T7 promoter-based plasmids
• Provided in a single-tube, single-use format—allows all transformation steps to take place in the same tube, thereby helping to save time and prevent contamination

Enhanced expression of nontoxic recombinant proteins
BL21 Star (DE3) cells contain the DE3 lysogen that carries the gene for T7 RNA polymerase under control of the lacUV5 promoter. IPTG is required to induce expression. This strainalso offers enhanced mRNA stability due to a mutation in the RNaseE gene (rne131) that reduces levels of endogenous RNases and mRNA degradation, thereby increasing the stability of mRNA transcripts and increasing protein yield. Protein expression is further enhanced by the absence of thelon and outer membrane (OmpT) proteases, which reduces degradation of heterologous proteins.

Note: The BL21 Star strains have higher basal expression of heterologous genes than BL21 strains, due to the increased stability of mRNA. Therefore, these strains may not be useful for expression of toxic genes.

Genotype:F^-ompT hsdS_B (r_B^-, m_B^-) galdcmrne131 (DE3)

Recovery

1.       Obtain an LB agar plate with the appropriate antibiotic.

2.       Using a sterile pipette tip, touch the bacteria growing within the punctured area of the stab culture. (A sterilized wire loop or sterile toothpick can be used in place of a sterile pipette tip.)

3.       3.Run this tip lightly over a section of the plate, as shown in the figure, to create streak #1.

4.      4 .Using another sterile pipette tip, pass through streak #1 and spread the bacteria over a second section of the plate, to create streak #2.

5.     5 .Using a third sterile pipette tip, pass through streak #2 and spread the bacteria over the last section of the plate, to create streak #3.

6.     6  .Grow overnight in a 37 ^o C incubator (unless a different growth temperature is indicated on the plasmid datasheet).

7.    7.In the morning, single colonies should be visible. If the bacterial growth is too dense, re-streak onto a new agar plate to obtain single colonies.