The key identifying characteristic for M. tuberculosis is the accumulation of niacin due to absence of the enzyme that converts free niacin to niacin ribonucleotide.
Mycobacterium leprae has never been cultured in artificial culture medium. It is grown in the 9 banded armadillo or in the footpads of mice. It takes 3-4 weeks to replicate.
Detects for the presence of cytochrome oxidase enzyme. If the organism contains the cytochrome oxidase enzyme, it catalyzes the oxidation of cytochrome C while reducing oxygen to water. Positive result is a color change to PURPLE within 60 to 90 secs.