The agar gel is able to support bacterial growth but the B-2-thienylalanine inhibits bacterial growth.
2.
A small disk of the filter paper is punched out and placed on an agar gel plate containing Bacillus subtilis and B-2-thienylalanine.
3.
Then a small disc is punched from the center of the spot of blood or urine, and the disc applied to the surface of a seeded, minimal-medium agar plate that contains added beta-2-thienylalanine.