Fig. 2.

Dendrogram showing cluster analysis of rRNA gene restriction fragment profiles of selected environmental and clinical strains of V. cholerae O1, O139, and non-O1 non-O139. Presence or absence of the CTX prophage and TCP island are shown in brackets. Of the 57 environmental strains shown, 51 strains were isolated by enrichment in rabbit ileal loops. Three TCP^- CT^- O1 strains, two NAG-ST-positive strains, and one toxigenic O1 strain were isolated from surface water by conventional culture. The clinical strains used for comparison are from our collection.