Mycobacterium tuberculosis is a slow-growing bacterium that causes tuberculosis. It has a waxy outer layer containing lipids like mycolic acids that make it acid-fast and resistant to drying. It can survive inside human macrophages. Diagnosis involves acid-fast staining of sputum smears under the microscope and culturing the bacteria in both solid and liquid media. The document provides detailed information on the characteristics, metabolism, cell wall structure, and laboratory diagnosis of M. tuberculosis.