[Culture optimization for protein expression in Escherichia coli].

OBJECTIVE: We developed a new culture-complex auto-inducing media (CAI) for heterogenous protein expression in Escherichia coli. METHODS: To test expression efficiency in the CAI, we constructed seven different plasmids named p-1, p-2, p-3, p-4, p-5, p-6 and p-7. These plasmids were transformed into E. coli BL21, then expressed in both Luria-Bertani madia LB and CAI. To improve the expression level even more, we analyzed the composition of the CAI and optimized the culture. RESULTS: The expression levels of seven fusion proteins in CAI were four times higher than those in Luria-Bertani. Through a series of changes we formed a new optimized culture (CAI-4). CONCLUSION: Comparing to the expression levels of these fusion proteins (P-1, P-2, P-3) in CAI, the expression levels of fusion proteins in CAI-4 increased 2-fold.