TABLE 3.

Conversion of lactate and acetate to butyrate in the cocultures between Bifidobacterium strains and Eubacterium hallii L2-7 with potato starch or fructo-oligosaccharides as the substrate

ParameteraValue with the following substrate and initial pH:SEMdP valued
StarchbFOSc
5.76.55.76.5SubstratepHSubstrate · pH
Lactate production (Fl.in)6.111.784.793.190.1450.761<0.001<0.001
Lactate outflow (Fl.out)7.672.966.014.120.1620.203<0.001<0.001
    To acetate (Fal)6.072.614.632.53
    To butyrate (Fbl)1.600.341.371.60
Acetate production (Fa.in)21.8117.5321.5920.020.8430.2480.0260.184
Acetate outflow (Fa.out)
    Total15.6912.2513.3215.360.7900.6600.4270.026
    To butyrate (Fba)8.677.007.9710.210.3070.0150.3970.003
Butyrate production (Fb)10.267.349.3411.810.276<0.0010.433<0.001
p 1 899085870.4310.0020.0860.192
p 2 48254428
  • a p 1, percentage of butyrate carbon (C) coming from acetate C, estimated from 13C acetate studies as Fba/Fb; p2, percentage of butyrate C coming from lactate C (either directly or indirectly via conversion to acetate), calculated as [(q × Fal) + Fbl]/Fb, with q being the proportion of acetate C going to butyrate C (Fba/Fa.out). All flows are expressed in terms of C2 units (mmol/liter per 21 h).

  • b Incubation with B. adolescentis L2-32.

  • c Incubation with B. adolescentis DSM 20083.

  • d From analysis of variance with substrate, pH, and their interaction (substrate · pH) as treatment effects. Values are based on 8 observations (4 residual df), except for Fb, which is based on 16 observations (12 residual df). Fal, Fbl, and p2 were calculated from combinations of mean values obtained from [13C]acetate and [13C]lactate studies, which did not allow for statistical analysis.