Fig. 3 Expression level of PCP vaccine antigen in four bicistronic T7 expression vectors.
Line M: Protein marker, Line 1: BL21 WT strain, Line 2: pET28 without target gene, Line 3-7 represented the target protein expression of vector pET28a, pET28-HT5, pET28-HT8, pET28-HP11Y, and pET28-HP12Y, respectively. (A), (B), and (C) represented the SDS-PAGE analysis of Oml1, Oml7, and ApxⅡ, respectively. Approximately 5 μL culture supernatant was loaded onto each lane. (D), (E), and (F) represented the relative protein yield of Oml1, Oml7 and ApxⅡ in BCD vectors per liter of cells, respectively.
Fig. 4 Effects of cultivation temperature and induction conditions on the production of PCP vaccine proteins.
For the optimization experiment of cultivation temperature, the OD600 and protein yield at 37 ℃ were used as the control, defined as 1. For the optimization experiment of induction conditions, the OD600 and protein yield with 1.0 mM IPTG addition and 0 h pre-induction period was used as the control, defined as 1. (A) Effect of cultivation temperature on Oml1 production. (B) Effect of cultivation temperature on Oml7 production. (C) Effect of cultivation temperature on ApxⅡ production. (D) Effect of IPTG concentration on Oml1 production. (E) Effect of IPTG concentration on Oml7 production. (F) Effect of IPTG concentration on ApxⅡ production. (G) Effect of pre-induction period on Oml1 production. (H) Effect of pre-induction period on Oml7 production. (I) Effect of pre-induction period on ApxⅡ production.