In a generic Ion Torrent library preparation workflow, two different linear adapters (A and P1) are ligated onto the DNA fragments in order to incorporate the necessary functionalities for sequencing. In both cases, each library fragment needs to have specific sequence features at the 5′- and the 3′-ends, respectively, in order to be functional ( Figure 1).
Nevertheless, they share some characteristics of the shotgun DNA library preparation process: the necessity of DNA fragmentation to a defined fragment size range followed by fragment end polishing and the addition of platform-specific adapters by ligation. Both platforms differ in the two key features of clonal library amplification and sequence detection. Today, Illumina and Ion Torrent instrument families are dominating the market of second-generation sequencing platforms. Therefore, efficient conversion of genetic material into a sequenceable library is urgently necessary.
Library preparation represents a decisive step in a sequencing workflow, and problems or limitations at this point can jeopardize the whole sequencing project as the available input material may be limited. High-throughput sequencing is widely used for a variety of sequence-based analyses in different fields.
