I had performed Phenol chloroform isoamyl alcohol extraction for isolating bacterial genomic dna from culture isolates using SDS. After addition of SDS and proteinase K, and incubating at 37 degrees for 1 hr, I added phenol chloroform isoamyl alcohol in the ratio 25:24:1. But my phase did not separate. I did not get a clear aqueous phase. Can anyone plz suggest the reason behind this?