TABLE 3.
Substrate consumed, growth, maximum products, 2,3-BD yield, and productivity during glucose fermentation by the P. polymyxa DSM 365 wild type and levansucrase null mutanta
| Parameter | 0 g/liter CaCl2 |
0.2 g/liter CaCl2 |
0.4 g/liter CaCl2 |
|||
|---|---|---|---|---|---|---|
| WT | LM | WT | LM | WT | LM | |
| Glucose consumed (g/liter) | 85.6 ± 3.9 A | 87.8 ± 1.9 A | 96.1 ± 3.1 A | 105.0 ± 0.0 A | 94.7 ± 2.7 A | 106.7 ± 2.5 B |
| Residual glucose (g/liter) | 23.7 ± 3.2 A | 21.45 ± 1.2 A | 13.2 ± 2.3 A | 4.3 ± 0.7 B | 14.5 ± 2.0 A | 2.5 ± 1.8 B |
| Cell dry weight (g/liter) | 6.0 ± 0.1 A | 8.1 ± 0.8 B | 7.5 ± 0.1 A | 10.3 ± 0.8 B | 7.0 ± 0.2 A | 10.8 ± 0.4 B |
| 2,3-BD (g/liter) | 30.7 ± 1.2 A | 29.8 ± 2.0 A | 34.2 ± 2.7 A | 39.0 ± 1.3 A | 34.5 ± 3.4 A | 39.4 ± 4.4 A |
| 2,3-BD production cell efficiencyb | 5.7 ± 0.2 A | 4.2 ± 0.3 B | 5.2 ± 0.5 A | 3.9 ± 0.3 B | 5.8 ± 0.3 A | 4.1 ± 0.4 B |
| EPS (g/liter) | 5.5 ± 0.4 A | 2.27 ± 0.1 B | 4.2 ± 0.2 A | 2.4 ± 0.3 B | 5.4 ± 0.5 A | 2.8 ± 0.2 B |
| 2,3-BD yield (g/g) | 0.36 ± 0.01 A | 0.34 ± 0.02 A | 0.36 ± 0.02 A | 0.37 ± 0.01 A | 0.37 ± 0.04 A | 0.38 ± 0.04 A |
| 2,3-BD productivity (g/liter/h) | 0.51 ± 0.02 A | 0.57 ± 0.09 A | 0.71 ± 0.06 A | 1.62 ± 0.05 B | 0.72 ± 0.07 A | 1.64 ± 0.19 B |
| Acetoin (g/liter) | 3.3 ± 0.0 A | 2.4 ± 0.4 B | 10.1 ± 2.1 A | 2.8 ± 0.4 B | 8.8 ± 1.1 A | 2.6 ± 0.3 B |
| Ethanol (g/liter) | 5.8 ± 0.1 A | 7.1 ± 0.3 B | 5.6 ± 0.4 A | 8.7 ± 0.7 B | 5.4 ± 0.5 A | 9.4 ± 0.2 B |
| Acetic acid (g/liter) | 0.0 ± 0.0 A | 1.7 ± 0.0 B | 0.6 ± 0.0 A | 2.5 ± 0.9 B | 0.0 ± 0.0 B | 2.9 ± 0.1 B |
a
Fisher’s LSD pairwise comparisons between wild type (WT) and levansucrase mutant (LM) were conducted. Values are means ± SD. Means with different uppercase letters across each row vary significantly at P < 0.05.
b
2,3-BD production cell efficiency was determined as the ratio of maximum 2,3-BD produced to the corresponding P. polymyxa cell growth.