TABLE 3.
Physiological parameters in chemostats with either cellobiose or ammonium limitation, at a dilution rate of 0.10 h−1a,b
| Parameter | Cellobiose limitation |
Ammonium limitation |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Reference strain (LL345) | AVM064 (Δppdk ΔmalE::peno-pyk) | AVM003 (Δppdk) | LL1084 (ΔnfnAB) | AG1715 (Δgogat) | Reference strain (LL345) | AVM064 (Δppdk ΔmalE::peno-pyk) | AVM003 (Δppdk) | LL1084 (ΔnfnAB) | AG1715 (Δgogat) | |
| Cellobiose in feed (g L−1) | 4.70 ± 0.03 | 4.98 ± 0.03 | 4.76 ± 0.08 | 4.87 ± 0.02 | 4.80 ± 0.04 | 4.69 ± 0.04 | 4.99 ± 0.00 | 4.63 ± 0.04 | 4.85 ± 0.02 | 4.77 ± 0.06 |
| Residual cellobiose (g L−1) | <0.01 | <0.01 | <0.01 | <0.01 | <0.01 | 1.83 ± 0.03 | 1.10 ± 0.04 | 1.66 ± 0.11 | 1.57 ± 0.10 | 2.23 ± 0.30 |
| Ammonium in feed (g L−1) | 0.69 ± 0.00 | 0.71 ± 0.02 | 0.67 ± 0.02 | 0.70 ± 0.01 | 0.70 ± 0.01 | 0.087 ± 0.003 | 0.089 ± 0.001 | 0.087 ± 0.001 | 0.089 ± 0.001 | 0.089 ± 0.001 |
| Residual ammonium (g L−1) | 0.51 ± 0.01 | 0.53 ± 0.01 | 0.50 ± 0.01 | 0.45 ± 0.01 | 0.45 ± 0.01 | <0.002 | <0.002 | <0.002 | <0.002 | <0.002 |
| qCellobiose (mmol gbiomass−1 h−1) | −2.19 ± 0.03 | −2.36 ± 0.08 | −2.07 ± 0.09 | −2.20 ± 0.02 | −2.15 ± 0.02 | −2.49 ± 0.02 | −2.54 ± 0.10 | −2.40 ± 0.10 | −2.45 ± 0.12 | −2.11 ± 0.06 |
| qAmmonium (mmol gbiomass−1 h−1) | −1.60 ± 0.04 | −1.62 ± 0.07 | −1.56 ± 0.04 | −2.14 ± 0.12 | −2.07 ± 0.06 | −1.43 ± 0.05 | −1.10 ± 0.05 | −1.33 ± 0.10 | −1.26 ± 0.03 | −1.41 ± 0.11 |
| Biomass yield (g gcellobiose−1) | 0.13 ± 0.00 | 0.12 ± 0.01 | 0.15 ± 0.01 | 0.13 ± 0.00 | 0.14 ± 0.00 | 0.12 ± 0.00 | 0.11 ± 0.00 | 0.13 ± 0.01 | 0.12 ± 0.01 | 0.14 ± 0.00 |
| Glycogen content (%, g gbiomass−1) | 1.1 ± 0.6 | NDg | ND | ND | ND | 31.5 ± 0.6 | ND | ND | ND | ND |
| Ethanol yield (mol molcellobiose−1) | 0.97 ± 0.06 | 1.55 ± 0.01 | 0.96 ± 0.03 | 0.96 ± 0.02 | 0.84 ± 0.07 | 1.07 ± 0.03 | 1.55 ± 0.05 | 0.84 ± 0.05 | 1.00 ± 0.02 | 0.77 ± 0.03 |
| Acetate yield (mol molcellobiose−1) | 1.38 ± 0.01 | 0.65 ± 0.02 | 1.46 ± 0.04 | 1.38 ± 0.02 | 1.38 ± 0.01 | 0.94 ± 0.01 | 0.61 ± 0.01 | 1.17 ± 0.12 | 1.01 ± 0.01 | 0.84 ± 0.07 |
| Formate yield (mol molcellobiose−1) | 0.11 ± 0.04 | 0.22 ± 0.02 | 0.10 ± 0.01 | 0.31 ± 0.01 | 0.07 ± 0.01 | 0.15 ± 0.01 | 0.32 ± 0.03 | 0.18 ± 0.05 | 0.13 ± 0.03 | 0.30 ± 0.12 |
| Lactate yield (mol molcellobiose−1) | 0.01 ± 0.00 | 0.02 ± 0.00 | 0.02 ± 0.00 | 0.01 ± 0.00 | 0.02 ± 0.00 | 0.07 ± 0.01 | 0.04 ± 0.02 | 0.06 ± 0.02 | 0.06 ± 0.00 | 0.04 ± 0.02 |
| Pyruvate yield (mol molcellobiose−1) | <0.01 | <0.01 | 0.01 ± 0.01 | <0.01 | 0.01 ± 0.00 | 0.09 ± 0.00 | 0.01 ± 0.00 | 0.02 ± 0.00 | 0.03 ± 0.00 | 0.02 ± 0.01 |
| Malate yield (mol molcellobiose−1) | <0.01 | 0.11 ± 0.02 | <0.01 | <0.01 | <0.01 | <0.01 | 0.03 ± 0.00 | <0.01 | <0.01 | <0.01 |
| Total amino acids yield (mol molcellobiose−1)c | 0.026 ± 0.001 | 0.031 ± 0.002 | 0.028 ± 0.002 | 0.030 ± 0.001 | 0.022 ± 0.001 | 0.116 ± 0.002 | 0.044 ± 0.006 | 0.107 ± 0.026 | 0.115 ± 0.009 | 0.038 ± 0.010 |
| CO2 yield (mol molcellobiose−1)d | 2.38 ± 0.02 | 2.00 ± 0.04 | 2.48 ± 0.06 | 2.18 ± 0.03 | 2.29 ± 0.05 | 2.07 ± 0.03 | 1.96 ± 0.01 | 2.06 ± 0.08 | 2.11 ± 0.02 | 1.48 ± 0.12 |
| H2 yield (mol molcellobiose−1) | 4.85 ± 0.06 | ND | ND | ND | 4.73 ± 0.05 | 2.44 ± 0.09 | ND | ND | ND | 4.26 ± 0.46 |
| Ex. protein yield (mol molcellobiose−1)e | 0.09 ± 0.00 | 0.06 ± 0.00 | 0.08 ± 0.00 | 0.10 ± 0.00 | 0.08 ± 0.00 | 0.05 ± 0.00 | 0.04 ± 0.00 | 0.05 ± 0.00 | 0.04 ± 0.00 | 0.04 ± 0.01 |
| Carbon recovery (%)f | 81 ± 1 | 77 ± 0 | 84 ± 2 | 81 ± 1 | 77 ± 1 | 77 ± 1 | 75 ± 1 | 77 ± 3 | 76 ± 1 | 64 ± 1 |
| Nitrogen recovery (%)f | 71 ± 2 | 66 ± 2 | 70 ± 2 | 54 ± 3 | 53 ± 2 | 87 ± 2 | 95 ± 3 | 96 ± 2 | 97 ± 1 | 72 ± 6 |
| Degree-of-reduction recovery (%)f | 70 ± 1 | 73 ± 0 | 72 ± 2 | 70 ± 1 | 66 ± 1 | 69 ± 1 | 71 ± 1 | 68 ± 2 | 68 ± 1 | 59 ± 1 |
| Degree-of-reduction recovery with H2 (%)f | 90 ± 1 | ND | ND | ND | 86 ± 2 | 79 ± 1 | ND | ND | ND | 76 ± 1 |
a
Data are shown as the average ± standard deviation for three biological replicates.
b
Negative values represent consumption, and positive values represent production.
c
Excluding cysteine.
d
Calculated from the fermentation product yields and biomass yield (see Materials and Methods).
e
Based on the molecular weight of a generalized protein composition (see Table S1 and Materials and Methods).
f
Calculated as the ratio of the total element or degree-of-reduction found in the products to the total element or degree-of-reduction in the consumed substrate (Tables S3–S5).
g
ND, not determined.