Resuspend pelleted bacterial cells in 250 μl Buffer P1 and transfer to a microcentrifuge tube.
Add 250 μl Buffer P2 and mix throughly by inverting the tube 4-6 times.
Add 350 μl Buffer N3 and mix immediately and thoroughly by inverting the tube 4-6 times.
Centrifuge for 10 minutes at 13,000 rpm in a table-top microcentrifuge.
Apply the supernatant to the QIAprep spin column by decanting or pipetting.
Centrifuge for 30-60 seconds. Discard the flow-through.
Recommended: Wash the QIAprep spin column by adding 0.5 ml Buffer PB and centrifuging for 30-60 seconds. Discard the flow-through.
Wash QIAprep spin column by adding 0.75 ml Buffer PE and centrifuging for 30-60 seconds.
Discard the flow-through, and centrifuge for an additional 1 minute to remove residual wash buffer.
To elute DNA, place the QIAprep column in a clean 1.5 ml microcentrifuge tube. Add 50 μl Buffer EB or water to the center of each QIAprep spin column, let stand for 1 minute, and centrifuge for 1 minute.