You will be given a definition of a task first, then some input of the task.
In this task, you are given a sentence. You are expected to write the name of the organism substances in the body mentioned in the input. Although there might be several correct answers, you need to write one of them.

A 20 - mul aliquot of the supernatant was added to 12 . 5 mul of assay buffer ( 20 mm ATP , 40 mm MgCl2 , 0 . 4 m Tris - Cl , pH 7 . 8 ) .
Output:
supernatant