First-generation DNA sequencing
1977: Frederick Sanger develops the chain termination sequencing method. It continues to be the election technique for DNA sequencing for the next 30 years.
Efforts are made in order to improve sequencing techniques, allowing development of increasingly automated DNA sequencing machines with fluorometric based detection and improved detection through capillary-based electrophoresis. These were the technologies used in the Human Genome Project (1990-2003).
Second-generation DNA sequencing
Polony and Pyrosequencing were the pioneers of this set of technologies, also known as Next-Generation Sequencing and distinguished for allowing massive parallel sequencing. Pyrosequencing is a ‘sequence-by-synthesis’ (SBS) technique like Sanger’s method, as they both require the direct action of DNA polymerase to produce the observable output. Polony inspired SOLiD (Sequencing by Oligonucleotide Ligation and Detection) but its commercialization was ineffective.
Illumina dye sequencing is the technique most widely used nowadays. This Solexa method of sequencing, which was later acquired by Illumina, also falls into the SBS category.
Third-generation DNA sequencing
Even though there isn’t consensus about what defines this generation of DNA sequencing technologies, some argue that single molecule sequencing (SMS) – without the requirement for DNA amplification and real-time sequencing are the focus features. The first technology to allow sequencing of non-amplified DNA was commercialized by Helicos BioSciences, which filed for bankruptcy in 2012. Today, the single molecule real-time (SMRT) platform from Pacific Biosciences is the technology that gathers the characteristics previously mentioned.
Fourth-generation DNA sequencing
The end of the SBS era begins with nanopore-based sequencers, already being commercialized by Oxford Nanopore Technologies.