Bacterial cells were harvested from broth media and centrifuged to concentrate into a microcentrifuge tube at a density of 2×10^6 cells/ml. Ethanol and sodium acetate were added to lyse the cells and release DNA. The solution was incubated at -20C for 2 hours then 100% ethanol was added and incubated at 20C for 1 minute to precipitate the DNA. The DNA was collected through repeated centrifugation and washing with ethanol before being resuspended in TE buffer for storage at -20C.

1. NASRIN AKTER

2.  Bacterial cells were harvested and fill up to 2
× 106 cell/ml in a 1.5ml micro-centrifuge
tube, centrifugation for 10 min at 10000×g.
 Then the supernatant was discarded.

3. Micro-organism in broth
media.
Taking 1.5ml in
microcentrifuge tube.

4.  1ml of 95% ethanol was added to the
harvested bacterial cells.
 50µl of 3M sodium acetate was added in the
tube and mixed well by pipetting and
vortexing.
 Micro-centrifuge tubes were incubated at
-20ºc for 2 hours .

5. Pipetting Vortexing

6. Centrifugation Discard the debrige

7.  1ml of 100% ethanol was added and the
solution was incubated at 20ºc for 1 min.
 The sample was centrifugated for 2 min at
10000 rmp and the supernatant containing
ethanol was discarded.

8. Discard rest of ethanol
 Centifugation was
repeated again at 10000
rmp . After that rest of
the ethanol was removed
with the help of
micropipette.
 Then the DNA is allowed
to dry up for few minute
to remove all the ethanol
in it

9. TE Buffer
 50µl of 1X TE buffer
was added in the
micro-centrifuge tube
and stored at -20ºc for
further use.