The most-commonly used phenotypic tests to identify and distinguish Mycobacterium strains and species from each other are described below.
The medium is supplemented with acetamide to a final concentration of 0.02M, adjusted to a pH of 7.0 and sterilized by autoclaving at 115°C for 30 minutes.
3 day arylsulfatase test is used to identify potentially pathogenic rapid growers such as M. fortuitum and M. chelonae.
Organisms producing the enzyme catalase have the ability to decompose hydrogen peroxide into water and free oxygen.
The test differs from that used to detect catalase in other types of bacteria by using 30% hydrogen peroxide in a strong detergent solution (10% polysorbate 80).
[1] Sole carbon source[1] Growth on Löwenstein–Jensen medium (LJ medium) Sole carbon and nitrogen source[1] The growth rate is the length of time required to form mature colonies visible without magnification on solid media.
M. tuberculosis (and some other species) lack this enzyme, and accumulate niacin as a water-soluble byproduct in the culture medium.