Gracilicutes

Gracilicutes (Latin: gracilis, slender, and cutis, skin, referring to the cell wall) is a clade in bacterial phylogeny.

Traditionally gram staining results were most commonly used as a classification tool, consequently until the advent of molecular phylogeny, the Kingdom Monera (as the domains Bacteria and Archaea were known then) was divided into four phyla, Gracilicutes (gram-negative, it is split in many groups, but some authors still use it in a narrower sense) Firmacutes [sic] (gram-positive, subsequently corrected to Firmicutes, today it excludes the Actinomycetota) Mollicutes (gram variable, later renamed Tenericutes and now Mycoplasmatota, e.g. Mycoplasma) Mendosicutes (uneven gram stain, "methanogenic bacteria" now known as methanogens and classed as Archaea)