Genetic evidence that serratamolide mediates hemolysis. A.

<p>Hemolysis and swarming by a mutant known to have elevated serratamolide production (<i>hexS</i>) is increased, and these phenotypes require SwrW. <b>B.</b> Elevated expression of a <i>swrW</i> promoter reporter in the <i>crp</i> mutant. Top, expression measured using a plasmid based-<i>tdtomato</i> reporter construct at t = 20 hrs. Asterisk indicates statistical significance (p<0.05) by the Student’s T-test. A representative experiment is shown (n = 4). Error bars indicate one standard deviation. Bottom, semi-quantitative RT-PCR analysis of RNA from WT and Δ<i>crp</i> mutant strains measured relative expression of <i>swrW</i> and internal standard 16S RNA from stationary phase cultures (OD₆₀₀ = ∼3.5). <b>C.</b> Arabinose-inducible expression of the <i>swrW</i> gene in an <i>swrW</i> transposon mutant strain restores hemolysis. <b>D.</b> Swarming motility defect of the <i>swrW</i> mutant is restored by induced expression of the <i>swrW</i> gene.