The S9 fraction has been used in conjunction with the Ames test[4] to assess the mutagenic potential of chemical compounds.[5] Chemical substances sometimes require metabolic activation in order to become mutagenic. Furthermore the metabolic enzymes of bacteria used in the Ames test differ substantially from those in mammals. Therefore to mimic the metabolism of test substance that would occur in mammals, the S9 fraction is often added to the Ames test.
The S9 fraction has also been used to assess the metabolic stability of candidate drugs