Table 3.
Effects of inoculation OD, nutrients, initial pH, pre-hydrolysis time, and temperature on glycerol, acetic acid, and ethanol production in the SSF process of washed SECS and whole slurry by Saccharomyces cerevisiae
| Washed SECS | Whole slurry (SECS + SEL) | |||||
|---|---|---|---|---|---|---|
| Experimental parameters | Glycerol (g/L) | Acetic acid (g/L) | Ethanol (g/L) | Glycerol (g/L) | Acetic acid (g/L) | Ethanol (g/L) |
| Initial OD600 | ||||||
| 1.0 | 1.21 (0.04) | 2.34 (0.08) | 27.3 (0.7) | 1.45 (0.06) | 3.01 (0.09) | 26.2 (0.7) |
| 4.0 | 1.25 (0.04) | 2.72 (0.06) | 28.6 (0.8) | 1.37 (0.05) | 3.56 (0.08) | 27.7 (0.9) |
| 8.0 | 1.51 (0.06) | 2.83 (0.04) | 26.7 (0.8) | 1.74 (0.04) | 4.28 (0.04) | 24.6 (0.8) |
| Nutrients | ||||||
| 0% | 1.17 (0.05) | 1.96 (0.05) | 26.4 (0.6) | 1.29 (0.04) | 3.05 (0.05) | 27.1 (0.6) |
| 50% | 1.25 (0.04) | 2.72 (0.06) | 28.6 (0.8) | 1.37 (0.05) | 3.56 (0.08) | 27.7 (0.9) |
| 100% | 1.62 (0.03) | 2.48 (0.09) | 25.7 (1.1) | 1.91 (0.04) | 4.34 (0.07) | 25.1 (1.0) |
| Initial pH | ||||||
| 4.0 | 0.84 (0.07) | 1.94 (0.05) | 25.3 (0.3) | 1.32 (0.07) | 3.03 (0.06) | 26.2 (0.6) |
| 4.8 | 1.25 (0.04) | 2.72 (0.06) | 28.6 (0.8) | 1.37 (0.05) | 3.56 (0.08) | 27.7 (0.9) |
| 5.5 | 1.61 (0.03) | 2.86 (0.08) | 25.4 (0.7) | 1.87 (0.08) | 4.01 (0.09) | 24.8 (1.2) |
| Effects of pre-hydrolysis time | ||||||
| 24 hours | 1.08 (0.06) | 2.77 (0.09) | 25.5 (0.7) | 1.23 (0.07) | 3.64 (0.06) | 24.9 (0.7) |
| 36 hours | 1.25 (0.04) | 2.72 (0.06) | 28.6 (0.8) | 1.37 (0.05) | 3.56 (0.08) | 27.7 (0.9) |
| 48 hours | 1.56 (0.04) | 2.32 (0.05) | 27.6 (0.5) | 1.71 (0.04) | 3.34 (0.05) | 25.9 (0.6) |
| Effects of temperature | ||||||
| 30°C | 1.12 (0.06) | 3.01 (0.08) | 25.8 (0.8) | 1.23 (0.03) | 4.28 (0.09) | 24.9 (0.4) |
| 33°C | 1.31 (0.04) | 3.21 (0.06) | 27.5 (1.2) | 1.46 (0.06) | 4.52 (0.06) | 26.5 (0.5) |
| 36°C | 1.25 (0.04) | 2.72 (0.03) | 28.6 (0.8) | 1.37 (0.05) | 3.56 (0.08) | 27.7 (0.9) |
| 39°C | 1.64 (0.07) | 2.52 (0.06) | 33.1 (0.6) | 1.73 (0.07) | 3.04 (0.07) | 32.1 (0.8) |
| 42°C | 1.55 (0.03) | 2.24 (0.07) | 31.5 (1.3) | 1.69 (0.09) | 3.01 (0.05) | 30.2 (1.0) |
Standard deviations are shown in parentheses. OD, optical density; SECS, steam-exploded corn stover; SEL, steam-exploded liquor; SSF, simultaneous saccharification and fermentation.