1) To harvest the transformants from 10 150 mm plates, prepare about 40 ml of water or 15% glycerol. Use 15% glycerol if the transformants are to be frozen.
2) Pour ~4 ml of water or 15% glycerol into each big plate.
3) Use the glass spreader to scrape cells to one corner of the plate. Tilt the plate by resting the plate on a 25 ml pipet or an eppendorf tube rack.
4) Use 5 ml pipet to transfer cell suspension into a 50 ml Falcon polypropylene tube.
5) Repeat steps 2-4 with all the plates, and transfer all the transformants into the same 50 ml tube.
6) Mix well by vortexing. Aliquot ~ 1 ml into an Eppendorf tube for genomic DNA isolation.
7) Freeze the remainder in 15% glycerol at –70¾C, if desired.

1) Thaw the transformants (if frozen).
2) Adjust the number of cells to a total of 12 OD600. This should result in a cell pellet that is about 100 µl in volume.
3) Resuspend the pellet in 200 µl of breaking buffer.
4) Add ~200 µl volume of glass beads, and 200 µl of phenol/chloroform and vortex at high speed for 3-5’.
5) Add 200 µl of TE buffer, vortex briefly.
6) Spin at top speed for 5’.
7) Transfer supernatant (~400 µl) to a new tube.
8) Perform phenol/chloroform extraction one more time by adding ~400 µl of phenol/chloroform to the tube.
9) Spin at top speed for 5’.
10) Transfer the aqueous layer to a new tube.
11) Add 1 ml of 100% EtOH, mix well.
12) Spin at top speed for 3’.
13) Remove supernatant and resuspend pellet in 0.4 ml TE buffer.
14) Add 30 µl of 1 mg/ml RNase A. Mix well.
15) Incubate at 37¾C for 15’.
16) Add 10 µl of 4 M NH4OAc and mix well.
17) Add 1 ml of 100% EtOH.
18) Spin at top speed for 3’.
19) Resuspend in 50 µl of TE buffer.
20) Determine the concentration using spectrophotometer.
21) Resolve 2-3 µl of genomic DNA on a 1% agarose gel to determine the quality of the preparation. The entire genomic DNA preparation should run as one discrete band larger than 20 kb in size.