TABLE 1.
Growth parameters, fermentation products, and carbon and electron recovery of strain RmG11 and Treponema zuelzeraea
| Substrate | Substrate consumed (mM) | Doubling time (h) | Turbidity (OD578) | Growth yield (g/mol)b | Substrate assimilated (mM)c | Products formed (mM) |
Recovery (%)g |
|||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ethanol | Acetate | H2d | Lactate | Pyruvate | Succinatee | CO2f | Carbon | Electron | ||||||
| Strain RmG11 | ||||||||||||||
| No substrateh | – | – | 0.004 | – | – | – | 0.2 | 0.5 | – | – | – | 0.2 | – | – |
| Glucose | 8.0 | 46 | 0.154 | 11.3 | 0.6 | 6.2 | 1.0 | 5.1 | 2.4 | 1.7 | – | 7.2 | 76 | 77 |
| Maltose | 5.0 | 58 | 0.122 | 14.2 | 0.2 | 8.3 | 1.3 | 5.4 | 2.4 | 2.4 | – | 9.6 | 75 | 75 |
| T. zuelzerae | ||||||||||||||
| No substrateh | – | – | 0.037 | – | – | – | 0.9 | 2.1 | – | – | – | 0.9 | – | – |
| Glucose | 8.0 | 12 | 0.508 | 36.5 | 2.0 | – | 12.4 | 26.5 | 0.4 | – | 0.3 | 12.1 | 101 | 104 |
| Mannose | 10.0 | 11 | 0.592 | 34.4 | 2.4 | – | 14.9 | 28.4 | 0.5 | – | 0.3 | 14.6 | 97 | 95 |
| Galactose | 9.0 | 10 | 0.563 | 36.2 | 2.3 | – | 14.0 | 27.0 | 0.2 | – | 0.2 | 13.8 | 100 | 99 |
| N-Acetylglucosamine | 9.0 | 19 | 0.309 | 18.7 | 1.2i | – | 25.0 | 31.4 | 0.4 | – | 0.1 | 24.9 | 99 | 99 |
| Xylose | 9.0 | 12 | 0.460 | 29.1 | 2.2 | – | 12.4 | 23.9 | 0.2 | – | 0.2 | 12.2 | 105 | 104 |
| Arabinose | 9.0 | 13 | 0.416 | 26.1 | 2.0 | – | 11.4 | 23.2 | 0.2 | – | 0.2 | 11.2 | 92 | 93 |
| Maltose | 5.0 | 13 | 0.711 | 83.6 | 1.5 | – | 14.4 | 26.5 | 0.4 | – | 0.3 | 14.1 | 99 | 97 |
| Cellobiose | 5.0 | 13 | 0.654 | 76.5 | 1.3 | – | 14.3 | 28.6 | 0.4 | – | 0.3 | 14.0 | 96 | 96 |
| Trehalose | 4.0 | 10 | 0.353 | 49 | 0.7 | – | 13.0 | 24.3 | 0.6 | – | 0.2 | 12.8 | 97 | 95 |
| Lactose | 5.0 | 20 | 0.456 | 51.9 | 0.9 | – | 15.4 | 32.5 | 0.1 | – | 0.1 | 15.3 | 90 | 91 |
The table shows results for strain RmG11 and T. zuelzerae cultivated with different substrates in basal medium. Precultures were grown on glucose. The values are means of results obtained with duplicate cultures (less than 10% deviation). –, not applicable/below detection limit.
Based on consumed substrate and the experimentally determined optical density (OD)/dry weight ratio for glucose-grown cultures (at OD578 = 0.1: 60 ± 5 mg L−1 for strain RmG11, n = 5; 62 ± 0.5 mg L−1 for T. zuelzerae, n = 2).
Based on an elemental composition of C4H8O2N for bacterial cell mass (84).
Expressed as if H2 were completely dissolved in the liquid phase to facilitate comparison with other products. 1 mM H2 corresponds to a partial pressure of 0.011 bar.
Strain RmG11 formed trace amounts of malate and fumarate.
Based on the assumption that the production of acetate and ethanol was accompanied by the formation, and succinate production was accompanied by the consumption of one CO2.
Based on dissimilated substrate.
Turbidity and products formed in basal medium without substrate were subtracted in the subsequent calculations.
Calculated as assimilated glucose.