This product is a chemically transformed super competent cell prepared using E. coli BL21 (DE3) strain, with a transformation efficiency of over 107 cfu/μg. Suitable for expression vectors of T7 promoter system (such as pET series), genotype F-ompThsdS(rB-mB-) galdcm (DE3).   The genetic background is clear; BL21 (DE3) strain, a high-efficiency protein expression host with T7 RNA polymerase as the expression system; Suitable for non-toxic protein recombinant expression   Store at -80°C (do not store in -20°C or liquid nitrogen!)