FIG 4.

C. difficile WT, C. hiranonis, C. hylemonae, and C. scindens utilize hydroxyproline when it is supplemented into a rich growth medium. Concentration of (A) hydroxyproline, (B) proline, and (C) 5-amino-valerate in BHI and in BHI + 600 mg/L (4.6 mM) hydroxyproline. Supernatants were taken after 24 h of growth by WT, hypD, C. hiranonis, C. hylemonae, or C. scindens. BHI alone (dotted line) and BHI + 600mg/L (4.6 mM) of hydroxyproline were used as controls. Statistical significance was determined using Student's t test with Welch’s correction to account for multiple comparisons (*, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001).