Table 2.
Effects of operating conditions on Thermotogae fermentation. MOPS: Morpholinopropane-1-sulfonic acid; HEPES: 2-[4-(2-hydroxyethyl) piperazin-1-yl] ethanesulfonic acid; TRIS: tris(idrossimetil)amminometano cloridrato; CDW: Cellular dry weight; AA: Acetic acid; LA: Lactic acid; ALA: Alanine; But: Butyrate; IA: Itaconic acid; GaR: recirculation of H2-rich biogas. Experiments were performed in different bioreactor configurations: B = Batch; CSTR = Continuous-flow Stirred-Tank Reactor; CSABR: Continuously Stirred Anaerobic Bioreactor; SB = Serum bottles. H2 column: a H2 yield = mol H2/mol consumed substrate; b mL/L culture. * Values extrapolated from the graphical representation of data.
| Parameter | Organism | T (°C) | Culture Type | Mixing Speed (rpm) | Reactor/Working Volume (L) | Substrate Loaded (mmol/L) | Operational Parameter |
Substrate Consumed (mmol/L) | Products | Ref. | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| H2 yielda |
AA (mmol/L) | LA (mmol/L) | ALA (mmol/L) | But (mmol/L) | ||||||||||
| PH2 (mbar) |
T.
maritima |
80 | B | 350 | 1.4/0.1 | Glucose (28) | PH2 = 7.1 ± 0.4 | 19.8 ± 1.1 | 2.34 | 25.0 ± 1.4 | 10.5 ± 0.5 | [107] | ||
| PH2 = 71.4 ± 2.1 | 19.7 ± 1.4 | 2.44 | 24.6 ± 2.4 | 11.0 ± 0.6 | ||||||||||
| PH2 = 178.5 ± 3.5 | 17.2 ± 0.9 | 2.32 | 20.1 ± 1.0 | 9.4 ± 0.5 | ||||||||||
| PH2 = 606.9 ± 18.7 | 13.4 ± 0.7 | n. d. | 13.0 ± 0.7 | 11.0 ± 0.6 | ||||||||||
| Stirring Speed (rpm) |
T.
neapolitana |
75 | CSABR | 300 | 3.0/1.0 | Xylose (33.3) | 300 | 31.43 | 2.13 ± 0.11 | 41.8 ± 2.16 | 1.78 ± 0.11 | [113] | ||
| 400 | 400 | 32.56 | 2.94 ± 0.15 | 50.12 ± 2.5 | 4.0 ± 0.22 | |||||||||
| 500 | 500 | 32.03 | 2.31 ± 0.12 | 44.62 ± 2.16 | 4.84 ± 0.22 | |||||||||
| 600 | 600 | 31.87 | 2.24 ± 0.11 | 41.12 ± 2.0 | 1.89 ± 0.11 | |||||||||
|
T.
neapolitana subsp. capnolactica |
80 | CSTR | 300 | 3.0/2.0 | Glucose (28) | 300 | 22.9 ± 2.7 | 3.0 ± 0.0 | 32.3 ± 4.3 | 10.0 ± 1.0 | 1.1 ± 0.1 | [69] | ||
| 500 | 500 | 24.8 ± 0.4 | 3.2 ± 0.1 | 37.7 ± 2.7 | 8.1 ± 0.2 | 1.0 ± 0.1 | ||||||||
| 300 | 300 + GaR | 24.7 ± 0.2 | 3.5 ± 0.2 | 39.2 ± 1.2 | 4.4 ± 0.1 | 0.9 ± 0.0 | ||||||||
| 500 | 500 + GaR | 24.9 ± 0.2 | 3.3 ± 0.1 | 38.7 ± 2.2 | 5.1 ± 0.5 | 0.8 ± 0.0 | ||||||||
| Gas sparging |
T.
neapolitana |
80 | B | 250 | 3.8/1.0 | Glucose (28) | N2 | 25.9 ± 1.3 | 2.8 | 44.8 ± 5.4 | 12.5 ± 2.9 | 1.3 ± 0.4 | [31] | |
| CO2 | 26.1 ± 1.2 | 2.8 | 35.6 ± 5.8 | 20.0 ± 6.1 | 2.7 ± 0.5 | |||||||||
| 75 | SB | no | 0.12/0.04 | Glycerol (108.6) | w/o | 13 ±0.6 | 1.24 ± 0.06 | 8.71 ± 0.35 | 0.36 ± 0.02 | [115] | ||||
| N2 | 14 ± 0.7 | 2.06 ± 0.09 | 10.04 ± 0.5 | 0.34 ± 0.02 | ||||||||||
| N2 plus pH control |
18 ± 0.9 | 1.98 ± 0.1 | 12.62 ± 0.53 | 0.25 ± 0.01 | ||||||||||
|
Gas
sparging |
T.
neapolitana |
77 | SB | 150 | 0.12/0.04 | Glucose (39) | w/o | - | 1.82 ± 0.09 | 64.28 ± 2.83 | 33.48 ± 1.47 | [110] | ||
| N2 | - | 3.24 ± 0.14 | 81.42 ± 3.49 | 36.77 ± 2.04 | ||||||||||
| Xylose (27) | w/o | - | 1.14 ± 0.07 | 40.30 ± 3.5 | 37.68 ± 1.7 | |||||||||
| N2 | - | 2.20 ± 0.13 | 71.94 ± 3.66 | 50.62 ± 2.38 | ||||||||||
|
T.
neapolitana subsp. capnolactica |
80 | SB | no | 0.12/0.03 | Glucose (28) | N2 | 25.7 ± 0.1 | 2.5 ± 0.06 | 27.3 ± 0.8 | 8.6 ± 0.2 | 2.5 ± 0.2 | [70] | ||
| CO2 | 28.3 ± 1.0 | 2.9 ± 0.1 | 22.1 ± 0.9 | 11.3 ± 0.1 | 3.0 ± 0.3 | |||||||||
|
T.
neapolitana |
80 | SB | no | 0.12/0.03 | Glucose (28) | N2 | 21.7 ± 0.6 | 2.5 ± 0.03 | 30.2 ± 0.4 | 2.2 ± 0.02 | 1.9 ± 0.3 | |||
| CO2 | 20.8 ± 2.3 | 1.9 ± 0.1 | 20.8 ± 0.1 | 1.2 ± 0.06 | 2.4 ± 0.3 | |||||||||
|
T.
maritima |
80 | SB | no | 0.12/0.03 | Glucose (28) | N2 | 23.2 ± 1.0 | 1.9± 0.06 | 25.5 ± 0.5 | 5.3 ± 0.8 | 2.4 ± 0.06 | |||
| CO2 | 19.9 ± 0.6 | 2.0 ± 0.1 | 18.3 ± 0.3 | 1.6 ± 0.2 | 2.3 ± 0.3 | |||||||||
|
T.
naphtophila |
80 | SB | no | 0.12/0.04 | Glucose (28) | N2 | 13.30 ± 1.10 | 2.20 ± 0.20 | 15.70 ± 0.10 | 1.40 ± 0.06 | 0.80 ±0.10 | |||
| CO2 | 20.80 ± 1.70 | 1.60 ± 0.20 | 19.20 ± 0.10 | 5.00 ± 0.02 | 1.80 ±0.05 | |||||||||
|
T.
petrophila |
80 | SB | no | 0.12/0.05 | Glucose (28) | N2 | 9.20 ± 1.30 | 3.00 ± 0.40 | 13.10 ± 0.05 | 2.00 ± 0.01 | 0.00 | |||
| CO2 | 14.20 ± 0.60 | 1.90 ± 0.10 | 12.60 ± 0.10 | 3.80 ± 0.02 | 0.30 ±0.10 | |||||||||
|
T.
caldifontis |
70 | SB | no | 0.12/0.05 | Glucose (28) | N2 | 10.90 ± 1.10 | 2.60 ± 0.10 | 16.70 ± 3.60 | 2.20 ± 0.50 | 3.20 ±0.90 | |||
| CO2 | 15.20 ± 0.90 | 1.80 ± 0.03 | 15.60 ± 1.50 | 2.30 ± 0.40 | 6.60 ±0.70 | |||||||||
|
T.
profunda |
60 | SB | no | 0.12/0.05 | Glucose (28) | N2 | 18.1 0 ±0.40 | 1.50 ± 0.20 | 15.90 ± 0.40 | 5.70 ± 0.10 | 1.40 ±0.06 | |||
| CO2 | 22.60 ± 1.70 | 0.70 ± 0.04 | 5.60 ± 0.20 | 2.3 ± 0.04 | 2.60 ±0.30 | |||||||||
| Pseudot. hypogea | 70 | SB | no | 0.12/0.05 | Glucose (28) | N2 | 8.80 ± 1.10 | 1.10 ± 0.30 | 6.40 ± 0.10 | 0.10 ± 0.00 | 2.90 ±0.10 | |||
| CO2 | 4.30 ± 0.10 | 0.50 ± 0.10 | 3.10 ± 0.20 | 0.10 ± 0.00 | 3.40 ±0.30 | |||||||||
| Pseudot. elfii | 70 | SB | no | 0.12/0.05 | Glucose (28) | N2 | 7.00 ± 0.90 | 2.00 ± 0.20 | 8.30 ± 0.06 | 0.20 ± 0.03 | 4.20 ±0.30 | [70] | ||
| CO2 | 6.70 ± 0.20 | 2.10 ± 0.10 | 7.80 ± 0.30 | 0.10 ± 0.01 | 10.0 ±0.30 | |||||||||
| Pseudot. lettingae | 70 | SB | no | 0.12/0.05 | Glucose (28) | N2 | 9.30 ± 0.50 | 1.20 ± 0.10 | 5.10 ± 0.05 | 0.20 ± 0.00 | 2.70 ±0.05 | |||
| CO2 | 8.10 ± 0.70 | 1.30 ± 0.30 | 4.40 ± 0.10 | 0.05 ± 0.01 | 3.70 ±0.20 | |||||||||
|
Gas
sparging |
Pseudot. subterranea | 70 | SB | no | 0.12/0.05 | Glucose (28) | N2 | 23.10 ± 2.10 | 1.80 ± 0.20 | 30.60 ± 6.90 | 16.20 ± 4.60 | 9.50 ±0.40 | ||
| CO2 | 27.00 ± 1.40 | 1.40 ± 0.10 | 31.90 ± 7.90 | 10.70 ± 4.0 | 20.0 ± 8.0 | |||||||||
| Pseudot. thermarum | 80 | SB | no | 0.12/0.05 | Glucose (28) | N2 | Complete | 1.8 ± 0.02 | 30.00 ± 2.20 | 6.50 ± 0.20 | 1.10 ±0.07 | |||
| CO2 | Complete | 1.50 ± 0.10 | 24.80 ± 0.70 | 5.60 ± 0.60 | 2.20 ±0.20 | |||||||||
|
Biomass
(g CDW/L) |
T.
neapolitana |
80 | Flask | 300 | 0.25/0.2 | Glucose (28) | 0.46 | 3.2 ± 0.04 | 2.39 | 34.3 ± 0.6 | 10.9 ± 0.4 | [68] | ||
| 0.91 | 2.9 ± 0.06 | 2.44 | 32.9 ± 0.8 | 12.2 ± 0.8 | ||||||||||
| 1.33 | 3.4 ± 0.01 | 2.58 | 32.3 ± 0.2 | 11.5 ± 0.5 | ||||||||||
| 1.74 | 3.0 ± 0.04 | 2.37 | 31.4 ± 1.1 | 14.7 ± 0.7 | ||||||||||
| pH |
T.
neapolitana subsp. capnolactica |
80 | SB | no | 0.12/0.03 | Glucose (28) | w/o | 18.54 ± 0.15 | 1.78 ± 0.29 | 22.76 ± 0.40 | 11.35 ± 0.62 | [67] | ||
| 0.01M MOPS | 26.42 ± 0.05 | 3.27 ± 0.18 | 26.65 ± 0.87 | 14.23 ± 0.22 | ||||||||||
| 0.01M TRIS | 25.55 ± 0.06 | 3.10 ± 0.10 | 26.77 ± 0.29 | 12.08 ± 0.89 | ||||||||||
| 0.01M HEPES | 25.99 ± 0.03 | 2.85 ± 0.40 | 25.56 ± 0.49 | 13.58 ± 0.88 | ||||||||||
| 0.01M HCO3− | 25.62 ± 0.10 | 2.20 ± 0.30 | 22.82 ± 0.84 | 14.63 ± 3.23 | ||||||||||
| 0.01M phosphate | 26.17 ± 0.26 | 2.78 ± 0.40 | 24.70 ± 0.59 | 14.92 ± 0.25 | ||||||||||
|
T.
neapolitana |
75 | CSABR | 300 | 3.0/1.0 | Glucose (28) | w/o pH control | 21.98 ± 1.11 | 2.05 ± 0.1 | 30.81 ± 1.5 | 3.33 ± 0.22 | [113] | |||
| plus pH control | 27.47 ± 1.39 | 3.2 ± 0.16 | 38.3 ± 2.0 | 1.77 ± 0.11 | ||||||||||
| Xylose (33.3) | w/o pH control | 29.77 ± 1.46 | 1.84 ± 0.09 | 34.47 ± 1.66 | 3.77 ± 0.22 | |||||||||
| plus pH control | 31.83 ± 1.6 | 2.22 ± 0.11 | 41.8 ± 2.0 | 1.66 ± 0.11 | ||||||||||
| pH |
T.
neapolitana |
75 | CSABR | 300 | 3.0/1.0 | Sucrose (14.6) | w/o pH control | 13.78 ± 0.7 | 3.52 ± 0.18 | 33.13 ± 1.65 | 3.11 ± 0.11 | [113] | ||
| plus pH control | 14.69 ± 0.06 | 4.95 ± 0.25 | 35.47 ± 1.83 | 2.11 ± 0.11 | ||||||||||
| Xylose (33.3) | w/o pH control | 29.44 | 1.85 ± 0.09 | 34.97 ± 1.66 | 3.88 ±0.22 | |||||||||
| pH = 6.5 | 32.57 | 2.71 ± 0.14 | 49.62 ± 2.50 | 3.44 ± 0.11 | ||||||||||
| pH = 7.0 | 32.9 | 2.84 ±0.14 | 50.29 ± 2.50 | 4.00 ± 0.22 | ||||||||||
| pH = 7.5 | 31.77 | 2.23 ± 0.11 | 41.96 ± 2.16 | 1.89 ± 0.11 | ||||||||||
| 75 | SB | no | 0.04/ 0.12 | Glycerol (108.6) | w/o HEPES | 16.96 ± 0.8 | 1.23 ± 0.06 | 9.14 ± 0.45 | [116] | |||||
| 0.05 M HEPES | 28.26 ± 1.4 | 2.73 ± 0.14 | 22.35 ± 1.05 | |||||||||||
|
T.
neapolitana |
80 | B | 250 | 3.8/1.0 | Glucose (28) | w/o NaHCO3 | 25.9 ± 1.3 | 2.8 | 44.5 ± 5.4 | 12.5 ± 2.69 | [31] | |||
| NaHCO3 14 mM | 25.4 ± 2.1 | 1.7 | 30.5 ± 4.9 | 18.0 ± 0.6 | ||||||||||
| NaHCO3 20 mM | 23.2 ± 1.9 | 1.0 | 44.4 ± 8.2 | 9.2 ± 2.7 | ||||||||||
| pH | NaHCO3 40 mM | 6.2 ± 0.8 | 2.7 | 18.0 ± 4.3 | 0.7 ± 1.5 | |||||||||
| 75 | B | no | 0.12/0.04 | Glycerol (108.6) | w/o IA | - | 438 ± 22 b | 7.49 ± 0.33 | 3.55 ± 0.22 * | [122] | ||||
| 1.5 g/L IA | - | 619 ± 30 b | 11.49 ± 0.5 | 1.66 ± 0.0 * | ||||||||||
|
Temp.
(°C) |
T.
neapolitana |
60 | SB | 75 | 0.26/0.05 | Glucose (14) | 60 | 2.2 * | 2.04 ± 0.05 | 2.0 | n. d | [65] | ||
| 65 | 65 | 5.0 * | 3.09 ± 0.3 | 7.0 | 0.05 | |||||||||
| 70 | 70 | 8.5 * | 3.18 ± 0.02 | 11.5 | 0.45 | |||||||||
| 77 | 77 | 11.0 ± 0.5 * | 3.85 ± 0.28 | 16.5 | 0.85 ± 0.1 | |||||||||
| 85 | 85 | 11.0 ± 0.5 * | 3.75 ± 0.49 | 18.0 ± 1.0 | 1.25 ± 0.05 | |||||||||
| Oxygen |
T.
maritima |
80 | B | 150 | 2.30/1.53 | Glucose (20) | w/o O2 | 17.41 | 38.09 b | 18.05 | 4.36 | 1.60 ± 0.2 | [129] | |
| with O2 | 19.30 | 31.75 b | 18.27 | 5.45 | 1.30 ± 0.2 | |||||||||