Table 2 Results for cell growth (measured by absorbance at 600 nm and converted to g (dry cell)/L) of E. coli BL21 (DE3) Star™/pAE/LigB (131-645aa), yield (mg/L) and productivity ((mg/L)/h) of soluble recombinant LigB (131-645aa) expressed in shaking flasks at 28°C for 4 h in TB using central composite design for two variables (Abs ind and IPTG for induction) with triplicate at the central point (CP)
Induction conditions | Cell growth (4 h ind) | Soluble LigB expression (4 h ind) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Assays | Total process time (h)a | Absind(x1) | IPTG (x2) | Abs600nm | Dry cell (g/L) | Model (g/L)b | Yield (mg/L) | Model (mg/L)b | Productivity (mg/L)/h | Model ((mg/L)/h)b | pH | Residual glucose (g/L) |
1 | 5.75 | 0.75 (-1) | 0.1 mM (-1) | 3.75 | 0.9 | 0.94 (-4.4%) | 180 | 177 (2%) | 31.3 | 31.2 (0.4%) | 6.64 | 6.4 |
2 | 5.83 | 0.75 (-1) | 1.0 mM (+1) | 3.31 | 0.8 | 0.74 (7.5%) | 166 | 163 (2%) | 28.4 | 28.4 (0.1%) | 6.75 | 6.8 |
3 | 6.75 | 2.0 (+1) | 0.1 mM (-1) | 6.33 | 1.6 | 1.54 (3.8%) | 288 | 286 (1%) | 42.7 | 42.6 (0.2%) | 6.36 | 5.2 |
4 | 7.00 | 2.0 (+1) | 1.0 mM (+1) | 5.19 | 1.3 | 1.34 (-3.1%) | 221 | 218 (1%) | 31.5 | 31.4 (0.5%) | 6.24 | 5.1 |
CP 1c | 6.25 | 1.4 (0) | 0.55 mM (0) | 4.83 | 1.2 | 1.14 (5.0%) | 198 | 211 (-7%) | 31.7 | 33.4 (-5.4%) | 6.63 | 6.4 |
CP 2 | 6.25 | 1.4 (0) | 0.55 mM (0) | 4.46 | 1.1 | 1.14 (-3.6%) | 214 | 211 (1%) | 34.2 | 33.4 (2.4%) | 6.53 | 5.8 |
CP 3 | 6.25 | 1.4 (0) | 0.55 mM (0) | 4.53 | 1.1 | 1.14 (-3.6%) | 210 | 211 (-1%) | 33.6 | 33.4 (0.6%) | 6.55 | 5.1 |