Practice question

Mycobacterium tuberculosis belongs to phylum Actinobacteria, also called Actinomycetota, defined as high G+C Gram-positive bacteria typically ranging 60 to 75 mol percent guanine-cytosine content. Members exhibit complex filamentous growth, mycolic acid-containing cell envelope conferring acid-fastness, slow growth rates, and resistance to desiccation and disinfectants. Actinobacterial 16S rRNA signatures and genome GC content cluster Mycobacterium with Streptomyces, Corynebacterium, and Nocardia. This lineage possesses unique arabinogalactan peptidoglycan and lipoarabinomannan, distinguishing it clearly from low G+C Firmicutes, Proteobacteria, and Bacteroidetes in modern bacterial systematics and clinical diagnostics.