The appropriate biosafety level for laboratory work involving Mycobacterium tuberculosis is BSL-3.

- Mycobacterium tuberculosis is the causative agent of tuberculosis, a serious infectious disease that primarily affects the lungs and can be transmitted through inhalation of infectious aerosols.
- Because of its high infectivity and potential to cause severe respiratory illness, strict containment procedures are necessary to protect laboratory personnel and prevent environmental contamination.

- BSL-3 laboratories are specifically designed for work with agents that can cause serious or potentially lethal disease through the inhalation route.
- Such facilities have specialized engineering controls, including negative air pressure, HEPA-filtered ventilation systems, and the use of biosafety cabinets.
- Laboratory staff must use personal protective equipment (PPE) and adhere to strict decontamination and access control protocols.

In contrast:
- BSL-1 is appropriate for agents not known to cause disease in healthy adults.
- BSL-2 is for agents of moderate hazard that pose a limited risk of aerosol transmission.
- BSL-4 is reserved for highly dangerous and exotic agents with a high risk of aerosol-transmitted infections that are frequently fatal and without available treatments or vaccines (e.g., Ebola virus).

Therefore, the correct biosafety level for work with Mycobacterium tuberculosis is BSL-3 to ensure adequate protection against airborne transmission risks.

Reference: Molecular Medical Microbiology, Volume 2, Chapter 59 - Mycobacteria