Yersinia ruckeri 16S rRNA copy numbers in the posterior intestine of rainbow trout. Quantitative real-time PCR shows the mean copy numbers of 16S rRNA gene in the exposed posterior intestine samples. There were significant differences of copy numbers of Y. ruckeri between time points (p value = 0.001), and between biotype 1 and biotype 2 (p value = 0.01). No Y. ruckeri was detected in unexposed control posterior intestine samples at any time point. Error bars indicate standard deviation (n = 9).