Extended Data Fig. 4: B. longum acidifies pH, produces acetate, and efficiently hydrolyzes conjugated primary bile acids.
B. longum was grown in regular media (blue) or media supplemented with 50 mM lactulose (red) or sucrose (green). (A) pH before and after 24 h of growth (n = 3 for 0 h; n = 6 for 24 h). (B) SCFA concentrations after 24 h of growth. n = 6 all conditions. (C and D) Supernatant BA quantified after 24 h B. longum growth in media containing 10μg/ml (C) TCA or (D) GCA. n = 4 all conditions. (B-D) *, p < 0.05, two-tailed t-test corrected for multiple comparisons. Plots representative of three independent experiments with ≥3 technical replicates. TCA: taurocholic acid, GCA: glycocholic acid, CA: cholic acid, CDCA: chenodeoxycholic acid, DCA: deoxycholic acid, and LCA: lithocholic acid. (E) Ex-GF mouse B. longum monocolonization experimental design. (F) Stool lactulose in GF mice receiving drinking containing 0, 10, 20, or 40 g/L lactulose or in SPF mice with water containing either 0 or 20 g/L lactulose. n = 1 for each condition. (G) Stool water content of GF mice receiving water with 0 or 20 g/L lactulose. n = 3 for each group. *, p < 0.05, two-tailed t-test. (H) Fecal quantitative 16 S metagenomics from ex-GF mice colonized with B. longum +/- lactulose in drinking water. n = 4 for each group except for day 1 in the water-treated group (one mouse did not produce a stool sample). n = 3 for the lactulose-treated group after day 1 (one mouse did not produce stool samples). (I – K) SCFA concentrations before and 10-days after Bifidobacteria inoculation. Each dot represents one sample from each mouse. Bar represents the median. *, p < 0.05, two tailed t-test comparing water to lactulose-treated mice at a time point. (L) Primary, (M) conjugated primary, and (N) secondary BA were measured. Each dot represents one sample from each mouse. Bar represents the median. *, p < 0.05, t-test comparing to time 0 for a given lactulose exposure.
