Extended lag phase of <i>S. enterica</i> wild-types and mutants in BIH broth with and without chlorine stress.

<p>Standard deviations represent three independent experiments. Significant differences in comparison to the parent strains under the same experimental condition are shown as *(<i>P</i><0.5), **(<i>P</i><0.001), and ***(<i>P</i><0.0001).</p

<i>S. enterica</i> aggregation assays.

<p>A) Aggregation of <i>S.</i> Typhimurium LT2 WT, <i>ΔycfR::cat</i> mutant, and <i>ΔycfR::cat</i> (JS-8) complement over 4 h. B) Aggregation of all <i>S. enterica</i> strains after 24 h incubation at room temperature. Standard deviations represent three independent experiments. Significant differences in comparison to the parent strains under the same condition are shown as *(<i>P</i><0.5), **(<i>P</i><0.001), and ***(<i>P</i><0.0001).</p

Statistical analysis of <i>S. enterica</i> spinach and tomato attachment assays with and without chlorine treatment.

a<p>ST LT2 wild type strain under the same condition is used as a reference in <i>t</i>-test analysis.</p>b<p>SP wild type strain under the same condition is used as a reference in <i>t</i>-test analysis.</p>c<p>(−) and ^d(+) represent without and with chlorine treatment, respectively.</p>e<p>All values are given as probability (<i>P</i>). <i>P</i>>0.05 indicates not significant (NS).</p

<i>S. enterica</i> crystal violet attachment assays.

<p>The bacterial attachment is quantified by OD₅₇₀ readings. A) Quantification of bacterial attachment in glass test tubes. B) Quantification of bacterial attachment in polystyrene 96-well plates. All assays were conducted for 24 h at 37°C. Middle horizontal line in each box represents the median of the entire data set; the upper and lower horizontal lines represent the upper quadrant median and the lower quadrant median, respectively. Detailed data analysis is given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057272#pone-0057272-t002" target="_blank">Table 2</a>.</p

Bacterial strains and plasmids used in this study.

a<p>California State Department of Health.</p>b<p>New England BioLabs.</p

Phylogenetic relatedness of <i>ycfR</i>, <i>sirA</i>, and <i>yigG</i> in <i>S. enterica</i> and their homologs in related bacterial species.

<p>Cladograms for <i>ycfR</i> (A), <i>sirA</i> (B), and <i>yigG</i> (C) with branch support values displayed at nodes were reconstructed using PhyML 3.0 aLRT and TreeDyn 198.3. (<a href="http://www.phylogeny.fr/" target="_blank">http://www.phylogeny.fr/</a>) (22–28). <i>Salmonella</i> sp. and <i>E. coli</i> sp. are indicated by blue and green boxes, respectively. An outgroup is indicated with a red box. Blue and green arrows indicate locations of <i>S.</i> Typhimurium and <i>S.</i> Saintpaul, respectively, in the cladograms.</p

Statistical analysis of <i>S. enterica</i> crystal violet attachment assays on glass and polystyrene surfaces.

a<p>ST LT2 wild type strain under the same condition is used as a reference in <i>t</i>-test analysis.</p>b<p>SP wild type strain under the same condition is used as a reference in <i>t-</i>test analysis.</p>c<p>All values are given as probability (<i>P</i>). <i>P</i>>0.05 indicates not significant (NS).</p

<i>S. enterica</i> attachment to fresh produce surface.

<p>A) Bacterial attachment to intact spinach leaves. B) Bacterial attachment to grape tomatoes. Attached bacteria were enumerated on XLD agar. Standard deviations represent three or four independent experiments. * indicates data is pΔresent but below the threshold for the graph. Detailed data analysis is given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057272#pone-0057272-t003" target="_blank">Table 3</a>.</p

<i>L. monocytogenes</i> attachment to fresh produce surface.

<p>A) Bacterial attachment to romaine lettuce. B) Bacterial attachment to cantaloupe rind. Standard deviations represent three independent experiments. Significant differences in comparison to the parent strains under the same condition are shown as * (<i>P</i><0.5), ** (<i>P</i><0.001), and *** (<i>P</i><0.0001).</p

<i>L. monocytogenes</i> soil survival.

<p>Bacterial survival in potting soil at 25°C for 30 days. Standard deviations represent three independent experiments performed in triplicate.</p