Vibrio cholerae embraces two major evolutionary traits as revealed by targeted gene sequencing

Vibrio cholerae inhabits aquatic environments worldwide and has over 200 recognized serogroups classified by O-polysaccharide specificity. Here, we report that V. cholerae selects either of two genetic traits during their evolution. Sequencing of the specific gene locus MS6_A0927 revealed that 339 of 341 strains of V. cholerae and closely related Vibrio species originating from 34 countries over a century carried either metY (M) (~1, 269 bp) or luxR-hchA (LH) (~1, 600 bp) genes, and consequently those vibrios were separated into two clusters, M (45.4%) and LH (54.6%). Only two strains contained both M and LH in the same locus. Moreover, extensive polymorphisms in those genes were detected in M and LH with 79 and 46 sequence variations, respectively. V. cholerae O1 strains isolated from cholera outbreaks worldwide, and some non-O1 strains evolving from O1 via exchange of genes encoding cell surface polysaccharides possessed LH alleles. Analysis of polymorphisms in the gene locus implicated a high degree of genetic diversity and identical subpopulations among the V. cholerae species

<i>Burkholderia pseudomallei</i> Biofilm Promotes Adhesion, Internalization and Stimulates Proinflammatory Cytokines in Human Epithelial A549 Cells - Fig 1

<p><b>(A)</b> Fluorescence microscopic views of the 2-day biofilms of <i>B</i>. <i>pseudomallei</i> H777, M10 and C17 grown statically on glass slides in LB broth at 37°C. The biofilms were stained with FITC-ConA and monitored under a Nikon Eclipse Ni-U fluorescence microscope (20× magnification). Strains H777 and C17 showed aggregation of surface-adherent bacteria whereas the biofilm mutant, M10, was rarely attached on the glass slide. (B) Confocal laser scanning micrographs of the 2-day biofilms of <i>B</i>. <i>pseudomallei</i> H777, M10 and C17 grown statically on glass slides in LB broth at 37°C. The biofilms were stained with FITC-ConA. The crossing lines in each images (x and y axes) indicate the correspondent vertical CLSM section (Z), indicating the thickness of the biofilm. The bars indicate 5 μm. The images were taken using a Zeiss 500 and a Zeiss 800 CLSM microscope (100× magnification).</p

Intracellular survival and multiplication of <i>B</i>. <i>pseudomallei</i> H777, M10 and C17 strains in human lung epithelial cells at MOI 10.

<p>The number of bacteria present were enumerated at 4, 8 and 12 h p.i. using the drop plate technique. Data are represented as means ± standard deviation from at least three independent experiments in triplicate wells.</p

Adhesion of <i>B</i>. <i>pseudomallei</i> H777, M10 and C17 to human lung epithelial cells at MOI 10.

<p>(A) Percentages of bacterial adhesion were determined by comparing the number of adherent bacteria to the inoculum. The numbers of CFU of cell-associated bacteria were counted after 1 h p.i. using the drop plate technique. Data represent the mean ± standard deviation of triplicates from at least three independent experiments. Asterisks denote statistical significance relative to H777 (<i>p</i> < 0.05). (B) Light microscopic images demonstrating <i>B</i>. <i>pseudomallei</i> H777, M10 and C17 adhesion to A549 cells. Bar represents 10 μm. Representative images from Giemsa stained specimens and visualized under 100× magnification.</p

Cytokine production by human lung epithelial cells (A549) in response to infection with <i>B</i>. <i>pseudomallei</i> H777, M10 and C17 strains.

<p>A549 cells were infected at MOI 10 and MOI 100. The culture supernatants were harvested at 8 h p.i. to measure cytokine levels. Data represent the means ± standard errors for triplicate wells of single representative experiments. Each experiment was performed at least three times. Asterisks denote statistical significance (<i>p</i> < 0.05).</p