Next-generation sequencing of phage-displayed peptide libraries.

Genetically encoded peptide libraries enabled the discovery of ligands for clinically relevant targets and functional materials. Next-generation sequencing (NGS) of these libraries improved the selection of ligands by detecting low abundant clones and quantifying changes in copy numbers of clones without many rounds of selection. Although NGS platforms have been widely used in genome assembly, quantification of gene expression (RNA-seq), and metagenomic analyses, few examples in the literature describe sequencing phage libraries. This chapter aims to provide a detailed method for sequencing a Ph.D.-7 phage display library by Ion Torrent. The main techniques covered in this chapter include (1) preparation of a phage library for sequencing, (2) sequencing, and (3) analysis of the sequencing data by a custom Matlab script.