Which characteristic defines members of the genus Mycobacterium?

Members of the genus Mycobacterium are characterized by a thick, waxy cell wall rich in mycolic acids. This unique structure contributes to their distinctive properties, including their resilience to environmental stresses and resistance to many standard disinfectants and antibiotics. The composition of their cell wall makes them more impervious to traditional staining techniques, which is why methods like the acid-fast stain are utilized to identify them. The mycolic acids also play a role in the pathogenicity of many Mycobacterium species, including Mycobacterium tuberculosis, which causes tuberculosis. This characteristic allows Mycobacterium species to survive within host macrophages by resisting phagocytosis and evading the immune response. Understanding this distinct cell wall structure is crucial for recognizing the behavior and characteristics of these bacteria in microbiological studies.