Enhancing expression of recombinant protein LTA of Escherichia coli in competent cells, Escherichia coli BL21 (DE3)

Abstract

Improvement of the recombinant protein expression level in E. coli strain BL21 (DE3) encoding
gene eltA of E. coli was conducted. The studied results showed that YJ medium had given the
best growth of E. coli BL21 (DE3) in comparison with other media in the same 1% initial seed
inoculum size (OD600 = 0.8), shaking 200 rpm at 370C for 8 hours. The highest level of fusion
protein (6xHis-LTA) was obtained from YJ medium in the same optimum culture condition (0.8
mM Isopropyl β-D-1-thiogalactopyranoside (IPTG) for 12 hours at 250C). Molecular weight of
purified 6xHis-LTA protein from 6xHis affinity chromatography was about 30 kDa.