Nucleotide sequence generation by barcode bead-colocalization in partitions
Comparison of common sequencing reads from sequencing based on partition-based barcoding can be used to improve sequencing results. Increased loading of barcodes per partition can also improve sequencing results.
1. A method of generating a nucleotide sequence of a DNA template, the method comprising:
(a) partitioning a nucleic acid sample into a plurality of partitions, the partitions comprising a particle comprising a solid support surface, the solid support surface having a plurality of oligonucleotide primers conjugated thereon, wherein the oligonucleotide primers comprise a barcode sequence and wherein different particles are distinguished by having different barcodes from one another, wherein at least some partitions have more than one particles per partition, and wherein different particles are conjugated to primers having different barcode sequences, wherein the nucleic acid sample is provided into the partitions as DNA template fragments or the nucleic acid sample is fragmented in the partitions to generate the DNA template fragments;
(b) in the partitions, linking oligonucleotide primers from the solid support to at least one DNA template fragment, thereby forming barcoded DNA template fragments;
(c) combining barcoded DNA template fragments from multiple partitions;
(d) generating a plurality of sequencing reads of the barcoded DNA templates;
(e) determining in a pairwise manner percent of sequencing reads of identical DNA template fragments shared between different barcodes;
(f) comparing the determined percent of identical DNA template fragments shared between different barcodes to a threshold value, wherein if two barcodes have a determined percent of identical DNA template fragments in common above the threshold value, the two barcodes are determined to be in the same partition; and
(g) generating a nucleotide sequence for the DNA template from the plurality of sequencing reads, wherein generating the nucleotide sequence comprises treating sequencing reads having different barcodes determined to be in the same partition as being from the same partition;
thereby generating a nucleotide sequence of a DNA template.
2. A method of distinguishing differently barcoded sequence reads originating from different partitions from sequence reads having different barcodes but originating from the same partition, the method comprising:
(a) partitioning a nucleic acid sample into a plurality of partitions, the partitions comprising a particle comprising a plurality of oligonucleotide primers, wherein the oligonucleotide primers comprise a barcode sequence and wherein different particles are distinguished by having different barcodes from one another, wherein at least some partitions have more than one particles per partition, and wherein different particles are conjugated to primers having different barcode sequences, wherein the nucleic acid sample is provided into the partitions as DNA template fragments or the nucleic acid sample is fragmented in the partitions to generate the DNA template fragments;
(b) in the partitions, linking oligonucleotide primers from the particle to DNA template fragments, thereby forming barcoded DNA fragments;
(c) combining barcoded DNA fragments from multiple partitions;
(d) generating a plurality of sequencing reads of the barcoded DNA;
(e) determining in a pairwise manner percent of sequencing reads of identical DNA fragments shared between different barcodes; and
(f) comparing the determined percent of identical DNA fragments shared between different barcodes to a threshold value, wherein if two barcodes have a determined percent of identical DNA template fragments in common above the threshold value, the two barcodes are determined to be in the same partition.
3. The method of claim 2 , wherein at least a majority of the plurality of oligonucleotide primers associated with a particle comprise the same barcode sequence.
4. The method of claim 2 , wherein the DNA fragments are sample DNA.
5. The method of claim 4 , wherein methyl cytosines in the sample DNA has been converted for methylation analysis prior to the partitioning.
6. The method of claim 4 , wherein the partitions comprise sample cells and the sample DNA is from the sample cells.
7. The method of claim 4 , wherein the partitions comprise sample cells and the sample DNA is cDNA generated from the sample cells.
8. The method of claim 4 , further comprising pre-encapsulating the sample cells in partitions.
9. The method of claim 2 , wherein the partitions further contain sample DNA to be sequenced and the DNA fragments are exogenous to the sample DNA.
10. The method of claim 4 , further comprising generating a nucleotide sequence for the sample DNA, wherein generating the nucleotide sequence comprises treating sequencing reads having different barcodes determined to be in the same partition as being from the same partition, thereby generating a nucleotide sequence of a DNA template.
11. The method of claim 2 , wherein the DNA fragments comprise heterologous end adaptor sequences.
12. The method of claim 2 , wherein the providing comprises randomly cleaving DNA.
13. The method of claim 12 , wherein the randomly cleaving comprises contacting the DNA with a transposase that introduces heterologous end adaptor sequences into the DNA to form DNA fragments comprising the heterologous end adaptor sequences.
14. The method of claim 2 , wherein at least 10% of the partitions have more than one particle per partition.
15. The method of claim 2 , wherein generating the nucleotide sequence comprises excluding sequencing reads from partitions comprising more particles than would be predicted by a Poisson distribution.
16. The method of claim 2 , comprising excluding sequencing reads from partitions comprising more particles than are physically possible as determined by the size of the particle in comparison to the size of the partition.
17. The method of claim 2 , wherein the particle is composed of a hydrogel that contains the oligonucleotides.
18. The method of claim 2 , wherein the particle comprises a solid surface to which the oligonucleotides are conjugated.
19. The method of claim 17 , wherein the oligonucleotides are released from the particles in the partitions.