TABLE 3.

Carbon and electron balances for A. caccae L1-92 and E. hallii L2-7

ParameterNo. of carbons or electronsa or mmol of substrate liter−1 consumedbNo. of carbons or electrons or mmol of product liter−1 formedb% Recovery
GlucoseAcetateLactate (d + l)SumFormateAcetateButyrateH2CO2cSum
No. of carbons/mol62312401
No. of electrons/mol24812282020
L1-92 (A. caccae)
    Grown on medium + dl-lactated
        Δ Concn29.8(17.2 + 23.7)0.135.613.040.9
        Δ Carbon59.6122.7182.30.1142.440.9183.3100.5
        Δ Electrons238.4490.8729.20.2712.426.0738.4101.3
    Grown on medium + glucose
        Δ Concn10.42.32.211.58.618.6
        Δ Carbon62.46.969.32.246.018.666.896.4
        Δ Electrons249.618.42688.8230.017.225695.5
L2-7 (E. hallii)
    Grown on medium + dl-lactate
        Δ Concn26.1(16.0 + 22.4)0.429.615.538.4
        Δ Carbon52.2115.2167.40.4118.438.4156.893.7
        Δ Electrons208.8460.8669.60.8592.031.062393.2
    Grown on medium + glucose
        Δ Concn10.22.02.78.012.018.4
        Δ Carbon61.261.22.05.432.018.457.894.4
        Δ Electrons244.8244.84.021.6160.024.0209.685.6
  • a References to electrons refer to electrons released upon formal oxidation to CO2.

  • b Experimental values are means of data from triplicate cultures after 24 h of growth. For L2-7, data are from the experiment shown in Fig. 1; standard deviations (also for the L1-92 experiment) were as indicated in the legend to Fig. 1.

  • c The value for carbon dioxide is calculated on the assumption that every 1 mol of lactate taken up (since formate production is minimal) releases 1 mol of CO2, while 1 mol of glucose utilized releases 2 mol of CO2 or formate: hence CO2 is calculated as (2 × glucose) − formate.

  • d YCFA medium was supplemented as shown above with either 33 mM dl-lactate or 10 mM glucose.