Figure 2.

Bifidobacterial bioconversion of indole to ILA occurs with Trp as an intermediate.

a and b, Concentrations of ILA (green bars) and Trp (blue bars) with m/z of [M + 1 + H]⁺ values in the supernatants of cell suspensions after incubation for 3 h with and without 4 μM of (2-¹³C)-indole plus l-serine. Values of three biological replicates were plotted, with bars representing the mean. See Supplementary Tables S6 (for a), S7 and S8 (for b), and Source Data (for a and b) for plot data and statistical values. a, Overnight cultures of the selected bifidobacterial strains grown in MRS medium were centrifuged, and the harvested cells suspended in PBS were used for the reactions. b, Cell suspensions of WT, trpB, and aldh strains were similarly prepared and used for the reactions.