TABLE 2.
Stoichiometry used for flux balance analysis (in mol basis) to simulate Accumulibacter’s anaerobic metabolisma
| Pathway | Stoichiometry | Enzyme(s) assayed in this study |
|---|---|---|
| Glycolysis (EMP) | (Glycogen)1 → 2 Pyr + 4 electrons | G6PDH (ED pathway) |
| Pyruvate to acetyl-CoA | Pyr → Ac-CoA + 2 electrons + CO2 | |
| Pyruvate to oxaloacetate | Pyr + CO2 ↔ OAA | |
| Oxidative TCA cycle branch |
OAA + Ac-CoA → Succ-CoA + 2 CO2 + 4 electrons |
ICDH, AKGDH |
| Reductive TCA cycle branch (reverse TCA cycle) | OAA + 4 electrons → Succ-CoA | MDH, FR |
| Glyoxylate shunt | 2 Ac-CoA → Succ-CoA + 2 electrons | ICL |
| Succinate-propionate shunt | Succ-CoA ↔ Pr-CoA + CO2 | |
| Ac-CoA* production (precursor for 3HB, 3HV and 3HMB) | Ac-CoA + electron → Ac-CoA* | AAR |
| Pr-CoA* production (precursor for 3H2MV, 3HV, and 3HMB) | Pr-CoA + electron → Pr-CoA* | AAR |
a
↔, reversible reaction; →, irreversible reaction. Note that these are lumped reactions, and each may involve several enzymatic steps. Please refer to Materials and Methods for a definition of Ac-CoA* and Pr-CoA*. A comprehensive overview of the physiological studies published on Accumulibacter supporting this stoichiometric model can be found in Document S1. “*” means plus 1 electron.