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Competent Cell Selection Guide

There are many properties to consider when choosing a competent cell for your experiments. Requirements such as high-quality plasmid preparations, blue/white screening, cytoplasmic disulfide bond formation, regulated protein expression and fast colony growth necessitate specific strain choices. The following selection chart highlights the characteristics of NEB's strains to help select the optimal strain for a particular experiment.
Product NEB # Characteristics
Strains for Cloning and Subcloning
NEB® Stable Competent E. coli (High Efficiency)
  • High quality plasmid preparations due to endA mutation
  • Rapid growth RecA- strain
  • T1 phage resistance (fhuA)
  • Value pricing
  • Free of animal products
NEB® Turbo Competent E. coli (High Efficiency)
  • Fastest growth – colonies visible after 6.5 hours
  • Plasmid preparation after 4 hours
  • Tight control/expression of toxic genes (F´lacIq)
NEB® 5-alpha Competent E. coli (High Efficiency)
  • Versatile cloning strain
  • DH5α™ derivative
NEB® 5-alpha F'Iq Competent E. coli (High Efficiency)
  • Toxic gene cloning
  • F´ strain with extremely high transformation efficiency
NEB® 10-beta Competent E. coli (High Efficiency)
  • Large plasmid and BAC cloning
  • DH10B™ derivative
dam-/dcm- Competent E. coli
  • Dam/Dcm methyltransferase free plasmid growth
Strains for Protein Expression
NEB® Express Competent E. coli (High Efficiency)
  • Versatile non-T7 expression strain
  • Protease deficient
NEB® Express Iq Competent E. coli (High Efficiency)
  • Control of IPTG induced expression from Plac, Ptac,Ptrc and T5lac
  • Protease deficient
T7 Express Competent E. coli (High Efficiency)
  • Most popular T7 expression strain
  • Protease deficient
T7 Express lysY Competent E. coli (High Efficiency)
  • T7 expression
  • Protease deficient
  • Better reduction of basal expression
T7 Express lysY/Iq Competent E. coli (High Efficiency)
  • T7 expression
  • Protease deficient
  • Highest level of expression control
SHuffle® Express Competent E. coli
  • Protease deficient/B strain
  • Enhanced capacity to correctly fold proteins with multiple disulfide bonds in the cytoplasm
SHuffle® T7 Express Competent E. coli
  • T7 expression
  • Protease deficient/B strain
  • Enhanced capacity to correctly fold proteins with multiple disulfide bonds in the cytoplasm
SHuffle® T7 Express lysY Competent E. coli
  • T7 expression
  • Protease deficient/B strain
  • Tightly controlled expression of toxic proteins
  • Enhanced capacity to correctly fold proteins with multiple disulfide bonds in the cytoplasm
SHuffle® T7 Competent E. coli
  • T7 expression/K12 strain
  • Enhanced capacity to correctly fold proteins with multiple disulfide bonds in the cytoplasm
BL21 Competent E. coli
  • Routine non-T7 expression
BL21(DE3) Competent E. coli
  • Routine T7 expression
Lemo21(DE3) Competent E. coli
  • Tunable T7 expression for difficult targets
NiCo21(DE3) Competent E. coli
  • Improved purity of target proteins isolated by IMAC

There are many properties to consider when choosing a strain for your experiments. Requirements such as plasmid preparation, blue-white screening, cytoplasmic disulfide bond formation and fast colony growth necessitate specific strain choices. Please check the Strain Properties Chart for a particular experiment.

DH5α™ and DH10β™ are trademarks of Invitrogen.
SHuffle® is a registered trademark of New England Biolabs, Inc.

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