The recovery of DNA uses AxyPrep DNA gel recovery kit of AXYGEN company, and the recovery steps are as follows:

1, cut off the agarose gel containing the target DNA under the ultraviolet lamp, suck up the liquid on the surface of the gel with a paper towel and chop it up. Calculate the gel weight (record the weight of 1.5 ml centrifuge tube in advance), which is taken as a gel volume (e.g. 100 mg= 100 μl volume);

2. Add 3 gel volumes of Buffer DE-A, heat at 75℃ after mixing evenly, and mix intermittently (every 2-3 min) until the gel block is completely melted (about 6-8 min);

3. Add 0.5 Buffer DE-B and mix evenly;

4. Suck the mixed solution in step 3, transfer it to a DNA preparation tube (placed in a 2 ml centrifuge tube (provided in the kit), 12,000×g centrifugation 1 min, and discard the filtrate;

5. Put the preparation tube back into a 2 ml centrifuge tube, add 500 μlBuffer W 1, 12,000×g for centrifugation for 30 s, and discard the filtrate;

6. Put the preparation tube back into a 2 ml centrifuge tube, add 500 μlBuffer W2, 12,000×g for 30 s, discard the filtrate, and wash it again with 700 μl Buffer W2 in the same way 12,000×g for centrifugation1min;

7. Put the preparation tube back to the 2 ml centrifuge tube, 12,000×g centrifugation1min;

8. Place the preparation tube in a clean 1.5 ml centrifuge tube (provided in the kit), add 25-30 μlEluent to the center of the preparation membrane, and let it stand at room temperature 1 min, 12,000×g centrifugation 1 min to elute the DNA.

If the fragment is large, such as more than several thousand kb, it is recommended to use the recycling kit of promega company, which is better.

There are instructions in the recycling kit for specific steps.