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From 2010.igem.org

Gram-positive Bacteria Chromosomal DNA Extraction Protocol

Contents 1 Puregene DNA isolation 2 Cell Lysis 3 RNase Treatment 4 Protein Precipitation 5 DNA Precipitation

Puregene DNA isolation

1. Grow overnight 7.5ml cultures in THYB containing 30μg/ml hyaluronidase.

Cell Lysis

1. Two sets of chromosomal DNA were being done.
2. Cells go through 3600 x g centrifugation for 15 minutes to pellet.
3. The supernatant in the tubes are poured away.
4. 0.5ml of cell suspension solution is added to the eppendorf tubes. The solution in the tubes are pipetted up and down to resuspend cells. The solution is then transferred to another 1.5ml tube.
5. 50μl of lysozyme and 7.5μl of lytic enzyme solution is added into each tube. The tubes are then inverted 25 times to mix the solution.
6. We then incubate them at 37°C for 30 minutes in order to digest the cell walls. The tubes are inverted occasionally during incubation.
7. To pellet the cells, we centrifuged it for 10 minutes and poured away the supernatant after that.
8. 0.5ml of cell lysis solution is added to the pelleted cells and the solution is pipetted up and down in order to lyse the cells. The samples are then heated for about 5 minutes at 80°C.

RNase Treatment

1. 6μl of RNase A solution is added into the cell lysate.
2. The tubes are inverted 25 times in order to allow the solutions to mix. They are then incubated at 60minutes at 37°C.

Protein Precipitation

1. The samples are cooled on ice.
2. 0.5ml of protein precipitation solution is added into each tube.
3. The solutions are vortexed at high speed for about 20 seconds for the protein precipitation solution to mix properly with the cell lysate. The samples are then placed on ice for 5 minutes.
4. They are then centrifuged at 13000rpm for 1 minute for the proteins to form a tight pellet.

DNA Precipitation

1. The supernatant containing the DNA are poured into a clean eppendorf tube.
2. 0.5ml of isopropanol is then added into each tube.
3. The solutions are then mixed by inverting gently for 50 times.
4. The mixture is centrifuged at 13000rpm for 1 minute.