TABLE 2.
P. pastoris cell growth, methanol consumption, FBG1 production, formaldehyde concentration and, specific activity of enzyme related to methanol metabolism during four processes.
| Fermentation strategies | DO-stat | μ-stat | m-stat | co-stat | ||
| P. pastoris cell growth | Ave. specific cell growth rate (μ, h–1) | 0.0056 ± 0.0064 | 0.0055 ± 0.0086 | 0.0055 ± 0.0054 | 0.0065 ± 0.0079 | |
| Max. specific cell growth rate (μ, h–1) | 0.020 ± 0.002 (24 h) | 0.026 ± 0.001 (24 h) | 0.016 ± 0.001 (48 h) | 0.026 ± 0.003 (24 h) | ||
| Max. OD600 | 405 ± 4 (96 h) | 368 ± 6 (60 h) | 390 ± 8 (96 h) | 397 ± 6 (108 h) | ||
| Methanol consumption | Max. methanol concentration (g/L) | 2.7 ± 0.06 (108 h) | 4.1 ± 0.09 (108 h) | 2 | 2 (40 h∼108 h) | |
| Ave. specific methanol consumption rate (g/g/h) | 0.084 ± 0.020 | 0.061 ± 0.013 | 0.069 ± 0.017 | 0.065 ± 0.009 | ||
| Max. specific methanol consumption rate (g/g/h) | 0.133 ± 0.003 (12 h) | 0.086 ± 0.001 (108 h) | 0.110 ± 0.002 (12 h) | 0.075 ± 0.001 (96 h) | ||
| FBG1 production | Max. volumetric activity (× 104, U/L) | 47.3 ± 1.9 (72 h) | 56.7 ± 1.2 (96 h) | 66.3 ± 0.9 (108 h) | 89.4 ± 1.4 (108 h) | |
| Max. specific activity (× 102, U/g) | 48.9 ± 1.2 (72 h) | 64.5 ± 1.9 (96 h) | 69.6 ± 1.5 (108 h) | 90.0 ± 2.1 (108 h) | ||
| Max. volumetric production (mg/L) | 220.0 ± 1.4 (72 h) | 249.8 ± 2.0 (96 h) | 312.6 ± 1.7 (96 h) | 403.3 ± 1.9 (108 h) | ||
| Max. specific production (mg/g) | 2.3 ± 0.1 (72 h) | 2.8 ± 0.2 (96 h) | 3.2 ± 0.2 (96 h) | 4.1 ± 0.2 (108 h) | ||
| Ave. specific production rate (mg/g/h) | 0.026 ± 0.007 | 0.027 ± 0.007 | 0.034 ± 0.008 | 0.034 ± 0.004 | ||
| Max. specific production rate (mg/g/h) | 0.036 ± 0.003 (60 h) | 0.037 ± 0.002 (72 h) | 0.043 ± 0.003 (36 h) | 0.050 ± 0.003 (72 h) | ||
| Metabolite | Formaldehyde (CH2O) | Max. value (mM/g-cell) | 19.5 ± 0.3 (108 h) | 10.2 ± 0.2 (108 h) | 11.4 ± 0.4 (108 h) | 3.0 ± 0.1 (108 h) |
| Ave. value (mM/g-cell) | 11.9 ± 5.9 | 4.8 ± 3.8 | 5.5 ± 3.6 | 1.7 ± 0.9 | ||
| Enzymes | Alcohol oxidase (AOX) | Max. value (U/g-cell) | 35.4 ± 0.4 (36 h) | 37.2 ± 0.4 (36 h) | 30.6 ± 0.3 (24 h) | 37.1 ± 0.2 (36 h) |
| Ave. value (U/g-cell) | 25.4 ± 5.4 | 18.8 ± 9.8 | 18.4 ± 5.0 | 24.9 ± 6.7 | ||
| Formaldehyde dehydrogenase (FLD) | Max. value (U/g-cell) | 97.4 ± 0.3 (24 h) | 168.3 ± 0.3 (36 h) | 133.3 ± 0.2 (96 h) | 167.1 ± 0.4 (36 h) | |
| Ave. value (U/g-cell) | 88.1 ± 11.5 | 130.5 ± 24.0 | 122.0 ± 13.9 | 152.2 ± 20.8 | ||
| Formate dehydrogenase (FDH) | Max. value (U/g-cell) | 146.3 ± 1.5 (60 h) | 143.1 ± 1.4 (48 h) | 102.3 ± 1.7 (72 h) | 154.8 ± 1.3 (48 h) | |
| Ave. value (U/g-cell) | 121.4 ± 33.7 | 103.8 ± 33.4 | 83.8 ± 13.5 | 128.1 ± 31.7 | ||
Results reflect the maximal and average values during entire 108 h induction. Experiments were done in triplicates. Three parallel measurements for each experiment were assayed. Values are indicated by means ± S.D. Ave. indicates average value of the entire induction period. Max. indicates maximal value.