Table 1. Summary of current next-generation technologies: methods used in sample preparation, molecule separation and sequencing, and advertised outputs.

First step for all methods is template fragmentation.

Method	Adapter type	Amplification?	Separation	Sequencing chemistry	Approximate read length (bases)†	Approximate maximum amount of data per run†
Roche 454*	Adapters	Emulsion PCR	Microbeads and ‘picotitre’ plate	Pyrosequencing	400–700	700 Mb
SOLiD	Adapters	Emulsion PCR	Beads on glass slide	Ligation	50–75	20 Gb
Illumina*	Adapters	Bridge amplification in situ	Glass slide hybridization	Reversible terminators	25–500	600 Gb
Helicos	Poly(A) adapter	No amplification	Flow-cell hybridization	Reversible terminators	25–55	35 Gb
PacBio	Hairpin adapters	Linear amplification	Captured by DNA polymerase in microcell	Fluorescently labelled dNTPs	1000	Not available
Ion Torrent*	Adapters	Emulsion PCR	Ion Spheres and high-density array	Detection of released H+	35–400	1 Gb

^*These technologies are available on platforms with different scales of throughput (Loman et al., 2012).

^†Approximate values based on data published on the companies’ websites on 9 March 2012. These data are for guidance only and are subject to change; readers interested in the details should consult either the manufacturers or those that are offering the sequencing service.