Tris(hydroxymethyl)aminomethane → Tris(hydroxymethyl)aminomethane

Participants

Reaction Steps

Colonies to be tested were emulsified in an Eppendorf-type microcentrifuge tube, in 30 microliter of polymyxin B-Tris NaCl buffer prepared as follows. Polymyxin B sulfate (Aerosporin; Burroughs Wellcome Co.) sterile powder was suspended in distilled water to a concentration of 100,000 U/ml; 0.5 ml of that solution was added to 2 ml of 0.1875M Tris-0.9% NaCl (pH 6.6) to yield a final solution of 20,000 U of polymyxin B per ml of 0.5M Tris-0.12M NaCl. Increasing the concentration of polymyxin B above 20,000 U/ml does not increase the sensitivity of the test. The bacterial suspension was incubated in polymyxin B-Tris-NaCl buffer at 37 degrees C. in a water bath for 5 to 30 min (a matter of convenience, depending on how many colonies were being tested) and centrifuged for 5 min in a tabletop Brinkmann Eppendorf Centrifuge 3200.

Provenance & Evidence