Fig. 2.

Contribution of ribD and ribN to V. cholerae growth in river water. Culturability of V. cholerae strains in filter-sterilized water from Mapocho river (a) and effect of 0.1 µM (b) or 2 µM (c) riboflavin (RF). Culturability of V. cholerae in experiments of co-inoculation of strains in water from the Mapocho river with or without 2 µM exogenous riboflavin and the same results expressed as competitive index (C.I.) for WT versus ∆ribD (d, e), WT versus ∆ribN (f, g) and ∆ribD versus ∆ribN (h, i). The average and standard deviation of three independent experiments is shown. *denotes statistically significant difference (P < 0.05) between WT and ∆ribD (a) or between the indicated bar and the initial inoculum (d, f, h) determined by t tests analysis