Commonly Used E. coli Strains

OpenWetWare offers a comprehensive repository of the genotypes of the most commonly used E. coli strains.

The following table points out some important features to take into account when working with some these E. coli strains.

Strain	Genotype	Observations
E. coli DH5α	F^– endA1 glnV44 *thi-1* recA1 relA1 gyrA96 deoR nupG purB20 φ80dlacZΔM15 Δ( lacZYA-argF)U169, hsdR17(r_K^–m_K⁺), λ^–	This strain is auxotrophic for thiamine ( thi-1) so that requires supplementation to be grown in minimal media such as DM. It has been observed that in minimum medium, even supplemented with thiamine (i.e. M9), this strain grows slowly compared to other strains such as BL21 and BW25113.
E. coli TOP10	F- mcrA Δ(mrr-hsdRMS-mcrBC) φ80lacZΔM15 ΔlacX74 nupG recA1 araD139 Δ(ara-leu)7697 galE15 galK16 rpsL(Str^R) endA1 λ^-
E. coli BL21	F^– ompT gal dcm lon hsdS_B(r_B^–m_B^–) [malB⁺]_K-12(λ^S)	BL21 is a B strain of E. coli, somewhat related to REL606. BL21 is protease deficient, which makes it an excellent strain for protein expression. It has much faster growth compared to cloning strains. Some labs do use BL21 for maintaining plasmids, but it is not ideal due to the presence of nuclease and the fact that the strain contains recA. BL21 (DE3) is an engineered variant of BL21 which contains T7 RNA polymerase controlled by the lac operator, commonly used for expression of large amounts of burdensome or toxic proteins.
E. coli BW25113	lacI⁺rrnB_T14 ΔlacZ_WJ16 hsdR514 ΔaraBAD_AH33 ΔrhaBAD_LD78 rph-1 Δ(araB–D)567 Δ(rhaD–B)568 ΔlacZ4787(::rrnB-3) hsdR514 rph-1

-- Main.CamiloGomez - 14 Dec 2017

Contributors to this topic

CamiloGomez, TylerDeJong

Topic revision: r2 - 2024-07-09 - 21:14:39 - Main.TylerDeJong