Table 6.
Impact of acetic acid on xylose fermentation by large isolate populations (A 620 = 50)
| A. Comparative fermentation of 75 g/L xylose in ODM with 5 to 15 g/L acetic acid by isolates precultured on xylose | ||||||||
|---|---|---|---|---|---|---|---|---|
| Adaptation stress | Isolate | Xylose uptake rate (g/L/hA) a,b | Ethanol productivity (g/L/hA) a,b | Ethanol yield per initial sugar (g/g) b | ||||
| AFEX CSH | 33 | Colony 5 | 0.090 | A | 0.0231 | AB | 0.26 | B |
| AFEX CSH > E | 28 | 2A.1.53R-E30-C3 | 0.078 | AB | 0.0197 | ABC | 0.23 | BCD |
| AFEX CSH > E (UV) | 30 | 2A.1.30R2-E40-C5 | 0.071 | BC | 0.0155 | ABCDE | 0.20 | DE |
| AFEX CSH > E > PSGHL | 13 | 2A.1.53R S100E40-1 | 0.069 | BC | 0.0249 | A | 0.23 | BCD |
| AFEX CSH > E > PSGHL | 16 | 2A.1.53R-1 | 0.078 | AB | 0.0175 | ABCD | 0.25 | BC |
| AFEX CSH > PSGHL | 11 | Colony 5-GP6 | 0.066 | BC | 0.0141 | BCDE | 0.21 | CD |
| PSGHL | 3 | Y-7124 S90E40-1 | 0.043 | D | 0.0080 | DE | 0.14 | F |
| PSGHL | 14 | Y-7124-6 | 0.053 | CD | 0.0105 | CDE | 0.16 | EF |
| PSGHL | 15 | Y-7124-10 | 0.045 | D | 0.0061 | E | 0.30 | A |
| Wild | 1 | Y-7124 | 0.060 | C | 0.0148 | BCDE | 0.19 | DE |
| Acetic acid (g/L) | ||||||||
| 5 | 0.083 | A | 0.0223 | A | 0.29 | A | ||
| 10 | 0.065 | B | 0.0152 | B | 0.22 | B | ||
| 15 | 0.048 | C | 0.0088 | C | 0.14 | C | ||
| B. Comparative fermentation of 75 g/L xylose in ODM with 5 to 15 g/L acetic acid by isolates precultured on glucose | ||||||||
| Adaptation stress | Isolate | Xylose uptake rate (g/L/hA) a,b | Ethanol productivity (g/L/hA) a,b | Ethanol yield per initial sugar (g/g) b | ||||
| AFEX CSH | 33 | Colony 5 | 0.014 | C | 0.0027 | B | 0.09 | C |
| AFEX CSH > E | 28 | 2A.1.53R-E30-C3 | 0.018 | C | 0.0039 | B | 0.09 | C |
| AFEX CSH > E (UV) | 30 | 2A.1.30R2-E40-C5 | 0.029 | BC | 0.0094 | AB | 0.16 | BC |
| AFEX CSH > E > PSGHL | 13 | 2A.1.53R S100E40-1 | 0.021 | C | 0.0047 | B | 0.18 | B |
| AFEX CSH > E > PSGHL | 16 | 2A.1.53R-1 | 0.019 | C | 0.0044 | B | 0.16 | BC |
| AFEX CSH > PSGHL | 11 | Colony 5-GP6 | 0.014 | C | 0.0049 | B | 0.15 | BC |
| PSGHL | 3 | Y-7124 S90E40-1 | 0.058 | A | 0.0165 | A | 0.26 | A |
| PSGHL | 14 | Y-7124-6 | 0.044 | AB | 0.0108 | AB | 0.27 | A |
| PSGHL | 15 | Y-7124-10 | 0.050 | A | 0.0141 | A | 0.23 | A |
| Wild | 1 | Y-7124 | 0.018 | C | 0.0050 | B | 0.13 | BC |
| Acetic acid (g/L) | ||||||||
| 5 | 0.043 | A | 0.0126 | A | 0.24 | A | ||
| 10 | 0.028 | B | 0.0071 | B | 0.17 | B | ||
| 15 | 0.014 | C | 0.0032 | C | 0.10 | C | ||
aRates are normalized relative to population density in absorbance units (A) at 620 nm.
bParameter variations based on two-way ANOVA (isolate × acetic ) were significant (P < 0.001). Within columns, values with no letters in common are significantly different at P < 0.05 (Student-Newman-Keuls pairwise method).