Methods and compositions for enriching either target polynucleotides or non-target polynucleotides from a mixture of target and non-target polynucleotides

摘要

Compositions and methods are provided for enriching non-target polynucleotides from a mixture of non-target and target polynucleotides where differences between the target polynucleotides and the non-target polynucleotides include the extent of modified bases that are present in a greater density in the target polynucleotides than in the non-target polynucleotides. This permits the target polynucleotides to be selectively and rapidly bound to an affinity matrix such as affinity protein-coated magnetic beads providing enrichment of the non-target polynucleotides in the supernatant. One use of this enrichment is to remove human genomic DNA from a mixture of DNAs obtained from human tissue samples to enrich for polynucleotides in a microbiome so as to characterize the microbiome by DNA sequencing. The modified bases are preferably methylated cytosines that can be bound to an affinity matrix comprising a methyl-binding domain (MBD).