260/230 ratio: 1.98. Perfect. 260/280 ratio: 2.12. Also perfect. But the concentration was 37 times higher than the average human stool DNA yield.
Someone had taken an empty Qiagen PowerFecal Pro bead tube, spiked it with a pure, unknown bacterial isolate and a trace of factory control DNA, and sent it through the clinical collection system as a real human stool sample. qiagen stool kit
Lena wasn’t amused. She pulled up the donor metadata again. Donor K was part of a longitudinal study on diet and inflammation. His previous samples—collected three months ago—were normal: 120 ng/µl, typical Firmicutes-to-Bacteroidetes ratio. But this new sample? It looked like someone had poured a concentrated culture of E. coli directly into the Qiagen bead tube before shipping. 260/230 ratio: 1
But tonight, sample #047—labeled only as “Donor K, male, 32, no known conditions”—gave her a nanodrop reading she’d never seen. Also perfect