Editing Gram-positive bacteria (section)

== Classification ==
Along with [[Bacterial cell structure#Cell morphology|cell shape]], Gram staining is a rapid method used to differentiate bacterial species. Such staining, together with growth requirement and antibiotic susceptibility testing, and other macroscopic and physiologic tests, forms a basis for practical classification and subdivision of the bacteria (e.g., see figure and pre-1990 versions of ''[[Bergey's Manual|Bergey's Manual of Systematic Bacteriology]]'').{{cn|date=July 2024}}

[[File:Gram Positive Classification.svg|thumb|none|Species identification hierarchy in clinical settings|660px]]

[[Bacterial taxonomy#History|Historically]], the kingdom [[Monera]] was divided into four [[Taxonomic rank|divisions]] based primarily on Gram staining: [[Bacillota]] (positive in staining), [[Gracilicutes]] (negative in staining), [[Mollicutes]] (neutral in staining) and Mendocutes (variable in staining).<ref>{{Cite journal |last1=Gibbons |first1=N.E. |last2=Murray |first2=R.G.E. |date=1978 |title=Proposals Concerning the Higher Taxa of Bacteria |journal=[[International Journal of Systematic and Evolutionary Microbiology]] |volume=28 |issue=1 |pages=1–6 |doi=10.1099/00207713-28-1-1 |doi-access=free}}</ref> Based on [[16S ribosomal RNA]] phylogenetic studies of the late microbiologist [[Carl Woese]] and collaborators and colleagues at the [[University of Illinois]], the [[monophyly]] of the gram-positive bacteria was challenged,<ref name="Woese 1987">{{Cite journal |last=Woese |first=C.R. |date=1987 |title=Bacterial evolution |journal=Microbiological Reviews |volume=51 |issue=2 |pages=221–271 |doi=10.1128/MMBR.51.2.221-271.1987 |pmc=373105 |pmid=2439888}}</ref> with major implications for the therapeutic and general study of these organisms. Based on [[Molecular phylogenetics|molecular studies]] of the 16S sequences, Woese recognised twelve [[bacterial phyla]]. Two of these were gram-positive and were divided on the proportion of the [[guanine]] and [[cytosine]] content in their [[DNA]]. The high G + C phylum was made up of the [[Actinomycetota|Actinobacteria]], and the low G + C phylum contained the [[Bacillota|Firmicutes]].<ref name="Woese 1987" /> The Actinomycetota include the ''[[Corynebacterium]]'', ''[[Mycobacterium]]'', ''[[Nocardia]]'' and ''[[Streptomyces]]'' genera. The (low G + C) Bacillota, have a 45–60% GC content, but this is lower than that of the Actinomycetota.<ref name="Brock" />