Carefully select at least one of each type of sucrose-fermenting colony from
the TCBS plate to inoculate a heart infusion agar (HIA) slant or another nonselective medium. Do not use nutrient agar because it has no added salt and does
not allow optimal growth of V. cholerae. Using an inoculating needle, lightly
touch only the very center of the colony. Do not take the whole colony or go
through the colony and touch the surface of the plate. This is to avoid picking
up contaminants that may be on the surface of the agar. If there is doubt that a
particular colony is sufficiently isolated from surrounding colonies, purify the
suspicious colony by streaking on another agar plate