Optimized DNA Extraction from Fecal and Bacterial Samples

DNA was extracted from spiked and clinical human fecal samples with QIAamp Fast DNA Stool Mini Kit (QIAGEN, Hilden, Germany) according to the manufacturer’s instructions for pathogen detection, however with the following modifications: In step 14, 110 μl Buffer ATE was used to increase DNA concentration. As starting material, 200 μl of fecal sample was used. DNA was extracted from chicken fecal samples with QIAamp Fast DNA Stool Mini Kit (QIAGEN, Hilden, Germany) according to the manufacturer’s instructions on pathogen detection step 1–4 (inhibition buffer and heat treatment), and on human DNA analysis step 5–14 (larger volumes of reagents) to maximize DNA yield according to [9 (link)]. However, in step 14, 100 μl Buffer ATE was used to increase DNA concentration. In addition, based on observation from other studies [10 (link)], the starting material was standardized to 0.2 g of fecal sample. DNA was extracted from C. jejuni strain 381 and C. jejuni strain DVI-SC181 with QIAamp Fast DNA Stool Mini Kit (QIAGEN, Hilden, Germany) according to the manufacturer’s instructions on pathogen detection.