6.5% Salt Tolerance Test

The salt tolerance test is performed using Tryptic Soy Broth with added sodium chloride (regular table salt) to create an overall salt concentration of 6.5%.  It is a selective medium which tests the ability of an organism to survive in a salt-rich environment.  Most organisms cannot survive in such an environment. Staphylococci, Enterococci,and Aerococci are expected to grow in this broth; other organisms are not.

You can find more discussion and the testing protocol here.

The tube above was inoculated with Staphylococcus aureus.  Notice the turbidity of the medium; the organism has grown in the salt broth.
The tube above was inoculated with Streptococcus pyogenes.  Notice the clarity of the broth; the organism did not grow in the salt broth.