BL21 (DE3) versus BL21 (lambda DE3) - (Sep/22/2005 )

Being a beginner in the world of molecular biology, I am having difficulties working out the difference between E.coli BL21(lambdaDE3) and BL21 (DE3) - is there a difference between the two and if so, what is it and how does this difference affect my use of it? Thanks for any help!

hi
BL21 and BL21-Gold derived competent cells are designed for high-level protein expression using T7 RNA polymerase-based expression systems. Three different derivatives are available to provide varying levels of expression control. The BL21(DE3) and BL21-Gold(DE3) competent cells are all-purpose strains for high-level protein expression and easy induction. The BL21(DE3)pLysS and BL21-Gold(DE3)pLysS competent cells provide tighter control for expression of toxic proteins. When used with the CE6 bacteriophage, the BL21 and BL21-Gold cells provide the tightest control of protein expression, important for extremely toxic proteins. In addition, the BL21 and BL21-Gold cells can be used for non-T7 RNA polymerase protein expression systems. All BL21 strains are deficient in the OmpT and Lon proteases, which may interfere with isolation of intact recombinant proteins. Use the BL21 or the BL21-Gold competent cells and its derivatives with T7 promoter-driven vectors, such as the pRSET and pET vectors.


Novagen technical documentation on BL21(DE3) cells.

Genotype of BL21-Gold (DE3) strain:
E. coli B F– ompT hsdS(rB– mB–) dcm+ Tetr gal (DE3) endA Hte

useful links : BL21DE3

Lambda is the capacity toproduce lambda phage for propagation in other bacterias. if you don't plan to use labda phage, you don't need to use BL21lamba DE3 strain.