Ultima Genomics - More Reads Per Bead?
Summary: Illumina produces less than one read per well due to low PF rates. Could Ultima have an edge here by using a method that generates a read from every bead?
A Background On Polycolonity
You’ve got this problem in DNA sequencing… in order to produce enough signal you generally want to create multiple amplified copies of a single template (fragment of DNA to be read). Illumina do this with bridge amplification. Ion Torrent (and others) with a process called emPCR.
In emPCR (emulsion PCR) you create a droplet in oil which is used as an isolated reaction vessel. You amplify the DNA on a solid support (bead). So in each droplet you need:
One bead
One template
Some primers
Some nucleotides
Sounds great! Except we have no way of making sure there’s exactly one bead and exactly one template in a droplet. And if you have multiple beads or templates… it gets messy.
If there’s no template… there will be no data generated.
If there’s more than one template the bead with contain amplified product from multiple templates (reads). The signal will be mixed, and again no useful data generated.
For this reason, you generally want to limit bead concentration such that there’s only at most one bead in each droplet. And just have to live with the fact that some beads will have no template and some multiple. This reduces the throughput of your platform. In Ion Torrent’s case, it seems like ~50% of wells are lost to these issues.
If you had a method that allowed 100% of beads to have product from a single template this could perhaps double throughput!
This is what Ultima appear to have been working on.