Practice question

Firmicutes, now reclassified as Bacillota, represent low G+C monoderm bacteria characterized by an exceptionally thick multilayered peptidoglycan network crosslinked with peptide interbridges and anionic teichoic acids. This robust wall retains crystal violet-iodine complex during Gram staining, conferring positive reaction and protection against osmotic stress. It serves as target for lysozyme and beta-lactams. Members include Bacillus, Clostridium, Staphylococcus, and Lactobacillus, exhibiting endospore formation in some genera. Despite occasional Gram-negative staining variants, thick peptidoglycan remains defining diagnostic feature separating them from Gracilicutes.