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. 2011;22A(6A2):6A.2.1-6A.2.17.
doi: 10.1002/9780471729259.mc06a02s22.

Genetic Screens and Biochemical Assays to Characterize Vibrio cholerae O1 Biotypes: Classical and El Tor

Mike S Son  1 , Ronald K Taylor  1
Affiliations

Genetic Screens and Biochemical Assays to Characterize Vibrio cholerae O1 Biotypes: Classical and El Tor

Mike S Son et al. Curr Protoc Microbiol. 2011.

Abstract

Vibrio cholerae serogroup O1 has two biotypes, classical and El Tor, the latter of which has displaced the prior and has been the causative agent for the ongoing seventh pandemic. However, reports since 2001 have identified clinical isolates of El Tor that have classical O1 biotype genetic and phenotypic characteristics. These El Tor variants have been emerging in clinical settings with increased frequency, including the 2010 cholera outbreak in Haiti. The emergence of El Tor variants warrants the proper and timely identification of clinical (or environmental) isolates' biotype. This unit describes some quick and simple genetic screens and phenotypic assays (biochemical characterization), to be performed simultaneously, commonly used to distinguish biotype and initiate characterization of any clinical (or environmental) isolates of Vibrio cholerae O1.

Keywords: Biochemical characterization; Classical biotype; El Tor biotype; Genetic screens; Vibrio cholerae O1.

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Figures

Figure 1
Figure 1
Sample grid used for patching. This grid can be used for testing citrate metabolism, where single colonies are patched individually into each numbered box. Notice only one box is marked WT for a wild-type control, however, other boxes may be used in the case of multiple controls, both positive and negative.
Figure 2
Figure 2
Milk agar plate used for casein hydrolysis by protease activity testing of classical O395 (HapR negative), El Tor C6706 (HapR positive), El Tor N16961 (HapR negative) and three El Tor variants (Var 1, Var 2 and Var 3 – all HapR positive).
Figure 3
Figure 3
Sample motility assay showing the relatively non-motile nature of classical O395, motile El Tor C6706, very motile N16961, and two variants (Iso #1 and Iso #2) with motility patterns similar to that of El Tor N16961.
See this image and copyright information in PMC

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