Isolation of nucleic acids

A method for partitioning a human stool homogenate comprising human DNA and bacterial DNA to produce a human target DNA preparation and a residual supernatant, the method comprising:

• a) treating a fluid fraction from a human stool homogenate with insoluble polyvinylpyrrolidone to bind inhibitor, if present, in an insoluble inhibitor complex, to produce a treated stool fluid;
• b) exposing the treated stool fluid to a target sequence-specific capture reagent comprising particles attached to oligonucleotides complementary to at least a portion of first human target DNAs under conditions wherein the first target sequence-specific capture reagent forms first capture complexes comprising the target sequence-specific capture reagent and the first human target DNAs;
• c) separating the first capture complexes from the treated stool fluid to produce:
• i) a human target DNA preparation comprising the first human target DNAs captured in first capture complexes in step b);
• and
• ii) a residual supernatant comprising bacterial DNA and human target DNAs not complementary to the oligonucleotides of the target-sequence specific capture reagent used in step b).