16S survey of the colonic mucosa of medicated swine
"Samples from up to 6 swine (biological replicates) were treated as follows for DNA extraction and V1-V3 16S rRNA gene amplification:  mucosa was scraped with a sterile glass slide, and the scrapings were stored in PBS at -20 degrees Celsius until DNA extraction.  Thawed scrapings were centrifuged at 10,000g to pellet the cells, followed by bead beating the resuspended pellet for bulk DNA extraction (kit by MoBio)"