Final answer:
The unique characteristics of acid-fast bacteria are due to the presence of mycolic acid in their cell walls. This waxy substance protects the bacteria and requires specialized staining techniques to be visualized.
Step-by-step explanation:
The chemical substance that contributes to the unique characteristics of acid-fast bacteria is mycolic acid. These bacteria, including members of the Mycobacteriaceae family, have a layer of waxy mycolic acids outside their peptidoglycan structure in the cell wall. This waxy layer provides protection against desiccation and immune system attack. In staining procedures, acid-fast cells retain the red color of the carbolfuschin stain because the mycolic acid layer requires a more robust staining method than the standard Gram stain to penetrate and reveal the bacterial cell walls.
The presence of mycolic acid-rich cell walls can be identified through the acid-fast staining technique, where cells that retain the red color are considered positive for mycolic acid.