- Euthanize the mouse.
- Open the peritoneal cavity and expose the intestines. See note.
- Carefully excise the mLN, removing the surrounding fat.
- Place the mLN in a sterile 40µm cell strainer (BD 352340), and place the strainer in a sterile 100mm petri dish (BD 351029).
- Add 500µl of sterile PBS (Ca2+/Mg2+ free) to the mLN.
- Using the flat top portion of a 3ml syringe plunger (BD 309585), mash the tissue to obtain a homogenate suspension.
- Collect the suspension from the petri dish and prepare serial dilutions (usually 1x10-1 to 1x10-3).
- Plate 200µl of each dilution in a blood agar plate (Tryptic soy agar with 5% sheep blood) for 24h at 37ºC.
- Proceed to DNA isolation. Note: Steps 2 to 8 are to be performed next to a Bunsen burner, or under a hood.