21 OCT 2026

To check growth on the 52 tetracycline streak plates from October 20, and to pour ampicillin (amp) selection plates for the next round of screening.

• 52 tetracycline streak plates (streaked Oct 20)

• LB agar

• Ampicillin (amp) stock solution

• Sterile empty Petri dishes (46 total)

Plate Check

• Removed the 52 tetracycline plates from the 37°C incubator.

• Checked each plate for colony growth and noted which isolates grew.

Amp Plate Pouring

• Prepared molten LB agar and supplemented it with ampicillin stock.

• Aseptically poured 46 amp plates and let them solidify.

• Stored the plates for streaking on October 22.

Most of the 52 tetracycline plates from October 20 showed colony growth.

Reading the tetracycline plates

Most isolates grew on tetracycline, so most of the purified clones still carry pAT64 and remain good candidates.

Why ampicillin next?

Imipenem, meropenem and ampicillin all belong to the same family of antibiotics, the β-lactams. Testing the isolates on ampicillin shows whether their resistance covers β-lactams more broadly. That gives a first clue about what kind of gene could be involved, for example one that makes an enzyme able to break down β-lactam antibiotics.

Next step

Streak isolates from the tetracycline plates onto the new ampicillin plates (Oct 22).