Comparison of Individual Strain Analysis to Microarray Results

<div><p>(A) Representative growth curves of 16 individual strains grown in the presence of solvent alone (DMSO, red curve) and 62.5 μM mechlorethamine (black curve). Growth was monitored by measuring the optical density (OD₆₀₀) of cultures every 15 min for 30 h. The fitness of each strain was defined by the difference between the average doubling times in mechlorethamine and in DMSO (see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.0010024#s4" target="_blank">Materials and Methods</a>).</p><p>(B) Correlation between growth rates of individual strains and microarray-based fitness estimates. The ratio of growth rates of the 186 individual homozygous deletion strains (the top 233 ranked mechlorethamine-sensitive strains as determined by three replicate microarray experiments minus 47 strains which exhibited a slow-growth phenotype when individually cultured in the absence of mechlorethamine) over an average wild-type growth rate are plotted on the x-axis against the average fitness-defect scores from three pool experiments on the y-axis. The correlation (<i>R</i>² = 0.7462) is highly significant (<i>p</i> = 5.4e<i>−</i>57).</p>