TABLE 3.

Recoveries of carbon and electrons for four butyrate-producing strains grown in batch culture

Strain and/or parameteraNo. of carbons or electronsb or concn of substrate consumedNo. of carbons or electrons or concn of product formedcRecovery (%)d
GlucoseAcetateFormateAcetateButyrateLactateH2Actual CO2Theoretical CO2
No. of carbons/mol621243011
No. of electrons/mol248282012200
C. eutactus L2-50
    Concn (mM)1017.13.97.00.93.51.10.8
    Carbon (mM)6017.17.828.02.71.10.894.0
    Electrons24034.231.214010.870093.0
F. prausnitzii A2-165
    Concn (mM)105.25.810.90.901216
    Carbon (mM)6010.45.843.62.7121696.7
    Electrons24041.611.621810.800085.4
Roseburia sp. A2-183
    Concn (mM)1010.23.412.70.95.516.222.0
    Carbon (mM)6020.43.450.82.716.222.098.1
    Electrons24081.66.8254.010.811.00087.9
R. intestinalis L1-82
    Concn (mM)108.72.312.70.910.412.123.1
    Carbon (mM)6017.42.350.82.712.123.1101.9
    Electrons24069.64.6254.010.820.80093.7
  • a For F. prausnitzii strain A2-165, we used medium YCFAG[60], which contains 10 mM glucose and 60 mM acetate. For the other strains, the medium was modified by omitting the Casitone and reducing the yeast extract content to 0.2% to minimize the presence of non-carbohydrate C. All incubations were under O2-free N2, and bicarbonate was omitted from the medium. C. eutactus, Coprococcus eutactus.

  • b References to electrons indicate electrons released upon formal oxidation to CO2.

  • c Data are averages of values from three separate fermentations.

  • d Total number of carbons or electrons recovered from the products formed from the substrates, expressed as a percentage and calculated from the theoretical CO2 values.