Kits for the preparation of DNA libraries for NGS
Library preparation for Illumina is composed of 4 main steps, the progress of which can vary according to the methods used:
1. DNA fragmentation
DNA is fragmented either enzymatically or by sonication to create smaller strands
2. End repair
Because DNA fragmentation does not result in homogeneous, blunt-ended fragments, end repair is needed to ensure that each molecule is free of overhangs, and contains 5' phosphate and 3' hydroxyl groups
3. Adapter ligation
Adaptors (short, double-stranded pieces of synthetic DNA) are then ligated to these fragments with the help of DNA ligase. The adaptors enable the sequence to become bound to a complementary counterpart. These adapters contain sequence motifs that are required for subsequent steps (clonal amplification and the actual sequencing).
4. Library amplification
Library amplification is required so that the received signal from the sequencer is strong enough to be detected accurately. The Illumina technology uses the "Bridge PCR" method.