title: DNA-Seq of human skin swabs
design: Prior to shotgun sequencing library preparation, purified DNA was further concentrated by collection with 1.8V Ampure XP, two washes with 80% ethanol, and elution in 10uL of nuclease-free H2O. Resulting DNA was immediately input into a modified Nextera XT library preparation. Modifications made to ensure success from samples below the recommended 1ng of input include using half the recommended volume of Nextera XT indexing primers for library amplification, and replacement of the proprietary Nextera XT polymerase with Kapa HiFi polymerase followed by 16 cycles of amplification. All libraries were then quantified using picogreen reagent and sized with an Agilent TapeStation prior to equimolar pooling for sequencing. Samples were sequenced on Illumina HiSeq 2500 or NextSeq instruments. Process-control samples introduced during shotgun library preparation included no template control introductions during DNA tagmentation, library indexing, and DNA elution negative controls after Ampure XP cleanup.