Examining the potential use and stability of guaiac faecal occult blood test cards for microbial DNA 16srRNA sequencing

Fresh stool samples from three healthy volunteers were applied to gFOBt cards. DNA was extracted from both the cards and fresh stool samples. A series of additional cards were prepared from one volunteer, and extracted at time points between 2 weeks and 3 years. The V4 region of the 16srRNA gene was amplified and sequenced on an Illumina MiSeq at 2x250bp read lengths. Data was analysed using QIIME software.Samples were grouped both by volunteer and by type (fresh or gFOBt), and compared a variety of ways: visual inspection of taxa, within-sample beta diversity, principal component analysis and t-tests of weighted and unweighted UniFrac distances. In all comparisons, samples grouped by volunteer, and not by sample type. The different time points showed no appreciable differences with increased storage time.