Mycobacterium tuberculosis

Tuberculosis is majorly caused by rod-shaped, non-motile, aerobic, acid-fast bacteria, Mycobacterium tuberculosis. The Mycobacterium tuberculosis complex comprises of 9 different members: M. tuberculosis, M. africanum, M. canetti​, M. bovis, M. caprae​, M. microti, M. pinnipedii M. mungi and M. orygis. 

Mycobacterium tuberculosis is stained using acid-fast stains such as Ziehl–Neelsen stain (red bacilli observed against contrasting background colour), because if gram stained, mycolic acid present in its cell wall does not absorb the stain. The bacteria gets killed at 60℃ when heat is provided for 15-20 minutes. Moreover, acid fast bacilli such as Mycobacterium tuberculosis withstand any decolourization by acid or alcohol, once stained. Lesion found in infected tissues is termed as Tubercle.

Mycobacterium tuberculosis is different from other mycobacterial strain in the production of catalase and niacin. M. tuberculosis takes around 18-24 hours to divide and exhibits slow growth. Egg-based media such as Lowenstein-Jensen media is usually used to grow the culture in laboratories. Colonies can be visible only after a few weeks' time. 












Source: https://en.wikipedia.org/wiki/Mycobacterium_tuberculosis