Figure 1.
Structures of common muricholic acids.
The primary bile acids (cholic acid, chenodeoxycholic acid, α-muricholic acid and β-muricholic acid) are listed. Deoxycholic acid and ω-muricholic acid are secondary bile acids and are products of the normal microbiota.
Figure 2.
α-muricholic acid inhibits germination by C. difficile UK1 spores.
(A) Germination of Clostridium difficile UK1 spores in complex medium supplemented with taurocholic acid (TA) or (B) medium supplemented with TA and 1 mM CDCA or (C) medium supplemented with TA and 1 mM α-muricholic acid. • 0 mM TA, ▪ 2 mM TA, ▴ 5 mM TA, ▾ 10 mM TA,♦ 20 mM TA or ○ 50 mM TA. (D) The inverse rate (1/v [sec/OD600]), versus the inverse taurocholate concentration (1/S [mM−1], was plotted. Apparent Km values for TA alone (•) and in the presence of α-muricholic acid (▪) were determined from the linear best fit.
Table 1.
Bile acid effects on C. difficile spore germination.
Figure 3.
α-muricholic acid inhibits germination by C. difficile M68 spores.
(A) Germination of Clostridium difficile M68 spores in complex medium supplemented with taurocholic acid (TA) or (B) medium supplemented with TA and 1 mM α-muricholic acid. • 0 mM TA, ▪ 2 mM TA, ▴ 5 mM TA, ▾ 10 mM TA,♦ 20 mM TA or ○ 50 mM TA. (C) The inverse rate (1/v [sec/OD600]), versus the inverse taurocholate concentration (1/S [mM−1], was plotted. Apparent Km values for TA alone (•) and in the presence of α-muricholic acid (▪) were determined from the linear best fit of the plotted data. (D) Hill Plot was generated to determine the apparent Km values for each condition.
Table 2. Minimum inhibitory concentration of bile acids for C. difficile strains.