Table 1.
Description of bacterial strains and plasmids included in this study.
Fig 1.
Activity of autoinducers CAI-1 and AI-2 produced by different strains as estimated using bioluminescence reporter assays, and expressed as relative light units (RLU, see text for details).
Recombinant E. coli strains carrying plasmids pJZ176 and pJZ365 produce CAI-1 and AI-2 respectively in their culture supernatants. Strains 126V0117, 86V1216 and 107V1216 are environmental V. cholerae non-O1 non-O139 isolates. Strain C6706 is a laboratory strain of V. cholerae O1, C6706ΔcqsS carry deletions of the gene encoding the receptor for CAI-1, whereas C6706ΔcqsA and C6706ΔluxS carry deletions of genes for biosynthesis of CAI-1 and AI-2 respectively.
Fig 2.
Multiple alignment of predicted amino acid sequences of (a) cqsS (b) cqsA and (c) HapR proteins.
Strains 86V1216 and 107V1216 are AI-2 overproducing V. cholerae non-O1 non-O139 isolated from water samples, whereas strains C6706 and N16961, and 126V0117 are typical V. cholerae O1 and non-O1 non-O139 respectively. Notably, strain 86V1216 does not carry the cqsA gene encoding CAI-1 synthase, and strain N16961 does not have an active hapR gene due to a natural frame shift mutation [21].
Table 2.
Recovery of Vibrio cholerae O1 CVEC in water samples by culturing under different conditions.
Table 3.
Co-occurrence of Vibrio cholerae non-O1 non-O139 strains carrying defined mutations in the cqsS gene and overproducing AI-2 with toxigenic V. cholerae O1 in surface water samples in Bangladeshd.