Fig. 1.
Fig. 2.
Fig. 3.
Fig. 4.
The values of independent variables (post induction temperature and dissolved oxygen) and the corresponding levels used in a central composite design (normalized in –2, –1, 0, 1 and 2)_
| Variable | Level | ||||
|---|---|---|---|---|---|
| –2 | –1 | 0 | 1 | 2 | |
| A: Post induction temperature (T) (°C) | 20 | 24.25 | 28.5 | 32.75 | 37 |
| B: Dissolved oxygen (DO) (%) | 10 | 20 | 30 | 40 | 50 |
The experimental design of 10 runs with two variables (post induction temperature and dissolved oxygen) and two responses (recombinant protein expression level and cell growth measured by absorbance at 600 nm)_
| Run | Post induction Temperature (T) (°C) | Dissolved Oxygen (DO) (%) | Response 1 Recombinant Protein Expression Level (%) | Response 2 Cell Growth (Abs 600nm) | ||
|---|---|---|---|---|---|---|
| 1 | –1 | 24.25 | –1 | 20 | 8.0 ± 0.9 | 1.83 ± 0.18 |
| 2 | +1 | 32.75 | –1 | 20 | 15.3 ± 1.2 | 2.60 ± 0.19 |
| 3 | –1 | 24.25 | +1 | 40 | 10.1 ± 1.0 | 1.02 ± 0.11 |
| 4 | +1 | 32.75 | +1 | 40 | 8.4 ± 0.8 | 5.60 ± 0.29 |
| 5 | –2 | 20.0 | 0 | 30 | 4.6 ± 0.4 | 1.36 ± 0.11 |
| 6 | +2 | 37.0 | 0 | 30 | 11.1 ± 1.1 | 3.40 ± 0.22 |
| 7 | 0 | 28.5 | –2 | 10 | 10.0 ± 0.9 | 1.87 ± 0.21 |
| 8 | 0 | 28.5 | +2 | 50 | 3.8 ± 0.4 | 2.05 ± 0.20 |
| 9 | 0 | 28.5 | 0 | 30 | 14.6 ± 1.2 | 2.45 ± 0.19 |
| 10 | 0 | 28.5 | 0 | 30 | 14.2 ± 1.2 | 2.60 ± 0.19 |
Parameter estimates and analysis of variance (ANOVA) of the model for recombinant production of β-NGF in E_ coli and for cell growth_
| Source of variation | Degree of freedom | Sum of squares | Mean squares | F-value | p value (Probe > F) | |
|---|---|---|---|---|---|---|
| Recombinant Protein Expression Level (%) | Model | 5 | 141.50 | 28.30 | 120.36 | 0.0002 |
| A-Temperature (°C) | 1 | 29.14 | 29.14 | 123.94 | 0.0004 | |
| B-Dissolved Oxygen (%) | 1 | 24.65 | 24.65 | 104.85 | 0.0005 | |
| AB | 1 | 20.25 | 20.25 | 86.13 | 0.0007 | |
| A2 | 1 | 42.94 | 42.94 | 182.62 | 0.0002 | |
| B2 | 1 | 56.17 | 56.17 | 238.90 | 0.0001 | |
| Error | 1 | 0.058 | 0.058 | – | – | |
| Total | 9 | 142.44 | – | – | – | |
| Cell Growth (Abs 600 nm) | Model | 3 | 11.58 | 3.86 | 6.82 | 0.0232 |
| A-Temperature (°C) | 1 | 7.41 | 7.41 | 13.10 | 0.0111 | |
| B-Dissolved Oxygen (%) | 1 | 0.54 | 0.54 | 0.96 | 0.3655 | |
| AB | 1 | 3.63 | 3.63 | 6.41 | 0.0445 | |
| Error | 1 | 0.011 | 0.011 | – | – | |
| Total | 9 | 14.98 | – | – | – |