Löwenstein–Jensen medium

The Löwenstein–Jensen medium, more commonly known as LJ medium, is a growth medium specially used for culture of Mycobacterium, notably Mycobacterium tuberculosis.

When grown on LJ medium, M. tuberculosis appears as brown, granular colonies (sometimes called "buff, rough and tough"). The media must be incubated for a significant length of time, usually four weeks, due to the slow doubling time of M. tuberculosis (15–20 hours) compared with other bacteria.