Editing Gram-positive bacteria

{{short description|Bacteria that give a positive result in the Gram stain test}}
[[File:Gram Stain Anthrax.jpg|thumb|right|300px|Rod-shaped gram-positive ''[[Bacillus anthracis]]'' bacteria in a [[cerebrospinal fluid]] sample stand out from round [[white blood cell]]s, which also accept the [[crystal violet]] stain.]]
[[File:Gram stain 01.jpg|thumb|300px|Violet-stained gram-positive [[cocci]] and pink-stained [[gram-negative]] [[bacillus (shape)|bacilli]]]]

In [[bacteriology]], '''Gram-positive bacteria''' are [[bacteria]] that give a positive result in the [[Gram stain]] test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of [[cell wall]].

The Gram stain is used by microbiologists to place bacteria into two main categories, Gram-positive (+) and [[Gram-negative bacteria|Gram-negative]] (−). Gram-positive bacteria have a thick layer of [[peptidoglycan]] within the cell wall, and Gram-negative bacteria have a thin layer of peptidoglycan.

Gram-positive bacteria retain the [[crystal violet]] stain used in the test, resulting in a purple color when observed through an [[optical microscope]]. The thick layer of peptidoglycan in the bacterial cell wall retains the [[Stain (biology)|stain]] after it has been fixed in place by iodine. During the decolorization step, the decolorizer removes crystal violet from all other cells.

Conversely, [[gram-negative bacteria]] cannot retain the violet stain after the decolorization step; [[Alcohol (chemistry)|alcohol]] used in this stage degrades the outer membrane of gram-negative cells, making the cell wall more porous and incapable of retaining the crystal violet stain. Their peptidoglycan layer is much thinner and sandwiched between an [[inner cell membrane]] and a [[bacterial outer membrane]], causing them to take up the [[counterstain]] ([[safranin]] or [[fuchsine]]) and appear red or pink.

Despite their thicker peptidoglycan layer, gram-positive bacteria are more receptive to certain [[cell wall#Bacterial cell walls|cell wall]]–targeting [[antibiotics]] than gram-negative bacteria, due to the absence of the outer membrane.<ref>{{Cite web |last=Basic Biology |date=18 March 2016 |title=Bacteria |url=https://basicbiology.net/micro/microorganisms/bacteria}}</ref>

== Characteristics ==
[[File:Gram-Cell-wall.svg|thumb|right|300px|Gram-positive and gram-negative cell wall structure]]
[[File:Gram-positive cellwall-schematic.png|thumb|right|Structure of gram-positive cell wall]]
In general, the following characteristics are present in gram-positive bacteria:<ref name="Brock">{{Cite book |last1=Madigan |first1=Michael T. |title=Brock Biology of Microorganisms |last2=Martinko |first2=John M. |date=2006 |publisher=Pearson Prentice Hall |isbn=978-0131443297 |edition=11th}}</ref>

# Cytoplasmic lipid membrane
# Thick [[peptidoglycan]] layer
# [[Teichoic acids]] and lipoids are present, forming [[lipoteichoic acid]]s, which serve as [[chelating]] agents, and also for certain types of adherence.
# Peptidoglycan chains are cross-linked to form rigid cell walls by a bacterial enzyme [[DD-Transpeptidase|<small>DD</small>-transpeptidase]].
# A much smaller volume of [[periplasm]] than that in gram-negative bacteria.

Only some species have a [[Bacterial capsule|capsule]], usually consisting of [[polysaccharide]]s. Only some species are [[flagellate]]s, and those with [[flagella]] have just two [[basal body]] rings for support, in contrast to the four found in Gram-negative bacteria. Both gram-positive and gram-negative bacteria commonly have a surface layer called an [[S-layer]]. In gram-positive bacteria, the S-layer is attached to the peptidoglycan layer. Gram-negative bacteria's S-layer is attached directly to the [[Bacterial outer membrane|outer membrane]]. Specific to gram-positive bacteria is the presence of [[teichoic acid]]s in the cell wall. Some of these are lipoteichoic acids, which have a lipid component in the cell membrane that can assist in anchoring the peptidoglycan.<ref>{{Cite journal |last1=Brown |first1=Stephanie |last2=Santa Maria |first2=John P. |last3=Walker |first3=Suzanne |date=2013-09-08 |title=Wall Teichoic Acids of Gram-Positive Bacteria |journal=Annual Review of Microbiology |language=en |volume=67 |issue=1 |pages=313–336 |doi=10.1146/annurev-micro-092412-155620 |issn=0066-4227 |pmc=3883102 |pmid=24024634}}</ref>

== 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" />

== Importance of the outer cell membrane in bacterial classification ==
{{Split section|Gram stain |discuss=Gram stain#Move Taxonomy sections here |date=November 2023}}
[[File:Mureine.svg|thumb|240px|The structure of peptidoglycan, composed of [[N-acetylglucosamine]] and [[N-acetylmuramic acid]]]]
Although bacteria are traditionally divided into two main groups, gram-positive and gram-negative, based on their Gram stain retention property, this classification system is ambiguous as it refers to three distinct aspects (staining result, envelope organization, taxonomic group), which do not necessarily coalesce for some bacterial species.<ref name="Gupta B">{{Cite journal |last=Gupta |first=R.S. |date=1998 |title=Protein phylogenies and signature sequences: A reappraisal of evolutionary relationships among archaebacteria, eubacteria and eukaryotes |journal=Microbiology and Molecular Biology Reviews |volume=62 |issue=4 |pages=1435–1491 |doi=10.1128/MMBR.62.4.1435-1491.1998 |pmc=98952 |pmid=9841678}}</ref><ref name="Gupta D">{{Cite journal |last=Gupta |first=R.S. |date=2000 |title=The natural evolutionary relationships among prokaryotes |url=http://www.life.illinois.edu/govindjee/Part2/15_Gupta.pdf |url-status=live |journal=Critical Reviews in Microbiology |volume=26 |issue=2 |pages=111–131 |citeseerx=10.1.1.496.1356 |doi=10.1080/10408410091154219 |pmid=10890353 |s2cid=30541897 |archive-url=https://web.archive.org/web/20130625170008/http://www.life.illinois.edu/govindjee/Part2/15_Gupta.pdf |archive-date=2013-06-25}}</ref><ref name="Desvaux et al., 2009">{{Cite journal |last1=Desvaux |first1=M. |last2=Hébraud |first2=M. |last3=Talon |first3=R. |last4=Henderson |first4=I.R. |date=2009 |title=Secretion and subcellular localizations of bacterial proteins: A semantic awareness issue |journal=Trends in Microbiology |volume=17 |issue=4 |pages=139–145 |doi=10.1016/j.tim.2009.01.004 |pmid=19299134}}</ref><ref name="Sutcliffe, 2010">{{Cite journal |last=Sutcliffe |first=I.C. |date=2010 |title=A phylum level perspective on bacterial cell envelope architecture |journal=Trends in Microbiology |volume=18 |issue=10 |pages=464–470 |doi=10.1016/j.tim.2010.06.005 |pmid=20637628}}</ref> The gram-positive and gram-negative staining response is also not a reliable characteristic as these two kinds of bacteria do not form phylogenetic coherent groups.<ref name="Gupta B" /> However, although Gram staining response is an empirical criterion, its basis lies in the marked differences in the ultrastructure and chemical composition of the bacterial cell wall, marked by the absence or presence of an outer lipid membrane.<ref name="Gupta B" /><ref name="Gupta A">{{Cite journal |last=Gupta |first=R.S. |date=1998 |title=What are archaebacteria: life's third domain or monoderm prokaryotes related to Gram-positive bacteria? A new proposal for the classification of prokaryotic organisms |journal=Molecular Microbiology |volume=29 |issue=3 |pages=695–707 |doi=10.1046/j.1365-2958.1998.00978.x |pmid=9723910 |s2cid=41206658}}</ref>

All gram-positive bacteria are bound by a single-unit lipid membrane, and, in general, they contain a thick layer (20–80&nbsp;nm) of peptidoglycan responsible for retaining the Gram stain. A number of other bacteria—that are bound by a single membrane, but stain gram-negative due to either lack of the peptidoglycan layer, as in the [[mycoplasma]]s, or their inability to retain the Gram stain because of their cell wall composition—also show close relationship to the gram-positive bacteria. For the bacterial cells bound by a single cell membrane, the term ''monoderm bacteria'' has been proposed.<ref name="Gupta B" /><ref name="Gupta A" />

In contrast to gram-positive bacteria, all typical gram-negative bacteria are bound by a cytoplasmic membrane and an outer cell membrane; they contain only a thin layer of peptidoglycan (2–3&nbsp;nm) between these membranes. The presence of inner and outer cell membranes defines a new compartment in these cells: the [[periplasmic space]] or the periplasmic compartment. These bacteria have been designated as [[diderm bacteria]].<ref name="Gupta B" /><ref name="Gupta A" /> The distinction between the monoderm and diderm bacteria is supported by conserved signature indels in a number of important proteins (viz. DnaK, GroEL).<ref name="Gupta B" /><ref name="Gupta D" /><ref name="Gupta A" /><ref name="Gupta C">{{Cite journal |last=Gupta |first=R.S. |date=2011 |title=Origin of diderm (gram-negative) bacteria: antibiotic selection pressure rather than endosymbiosis likely led to the evolution of bacterial cells with two membranes |journal=Antonie van Leeuwenhoek |volume=100 |issue=2 |pages=171–182 |doi=10.1007/s10482-011-9616-8 |pmc=3133647 |pmid=21717204}}</ref> Of these two structurally distinct groups of bacteria, monoderms are indicated to be ancestral. Based upon a number of observations including that the gram-positive bacteria are the major producers of antibiotics and that, in general, gram-negative bacteria are resistant to them, it has been proposed that the outer cell membrane in gram-negative bacteria (diderms) has evolved as a protective mechanism against [[antibiotic]] selection pressure.<ref name="Gupta B" /><ref name="Gupta D" /><ref name="Gupta A" /><ref name="Gupta C" /> Some bacteria, such as ''[[Deinococcus]]'', which stain gram-positive due to the presence of a thick peptidoglycan layer and also possess an outer cell membrane are suggested as intermediates in the transition between monoderm (gram-positive) and diderm (gram-negative) bacteria.<ref name="Gupta B" /><ref name="Gupta C" /> The diderm bacteria can also be further differentiated between simple diderms lacking lipopolysaccharide, the archetypical diderm bacteria where the outer cell membrane contains lipopolysaccharide, and the diderm bacteria where outer cell membrane is made up of [[mycolic acid]].<ref name="Desvaux et al., 2009" /><ref name="Gupta C" /><ref name="pmid19667386">{{Cite journal |last1=Marchandin |first1=H. |last2=Teyssier |first2=C. |last3=Campos |first3=J. |last4=Jean-Pierre |first4=H. |last5=Roger |first5=F. |last6=Gay |first6=B. |last7=Carlier |first7=J.-P. |last8=Jumas-Bilak |first8=E. |date=2009 |title=Negativicoccus succinicivorans gen. Nov., sp. Nov., isolated from human clinical samples, emended description of the family Veillonellaceae and description of Negativicutes classis nov., Selenomonadales ord. nov. and Acidaminococcaceae fam. nov. In the bacterial phylum Firmicutes |journal=International Journal of Systematic and Evolutionary Microbiology |volume=60 |issue=6 |pages=1271–1279 |doi=10.1099/ijs.0.013102-0 |pmid=19667386 |doi-access=free}}</ref>

=== Exceptions ===
In general, gram-positive bacteria are monoderms and have a single [[lipid bilayer]] whereas gram-negative bacteria are diderms and have two bilayers. Exceptions include:
* Some taxa lack peptidoglycan (such as the class [[Mollicutes]], some members of the [[Rickettsiales]], and the insect-endosymbionts of the [[Enterobacteriales]]) and are [[Gram stain#Gram-variable and gram-indeterminate bacteria|gram-indeterminate]].
* The [[Deinococcota]] have gram-positive stains, although they are structurally similar to gram-negative bacteria with two layers.
* The [[Chloroflexota]] have a single layer, yet (with some exceptions<ref>{{Cite journal |last1=Yabe |first1=S. |last2=Aiba |first2=Y. |last3=Sakai |first3=Y. |last4=Hazaka |first4=M. |last5=Yokota |first5=A. |date=2010 |title=''Thermogemmatispora onikobensis'' gen. nov., sp. nov. And ''Thermogemmatispora foliorum'' sp. nov., isolated from fallen leaves on geothermal soils, and description of Thermogemmatisporaceae fam. nov. and Thermogemmatisporales ord. Nov. Within the class Ktedonobacteria |journal=International Journal of Systematic and Evolutionary Microbiology |volume=61 |issue=4 |pages=903–910 |doi=10.1099/ijs.0.024877-0 |pmid=20495028 |doi-access=free}}</ref>) stain negative.<ref>{{Cite journal |last=Sutcliffe |first=I.C. |date=2011 |title=Cell envelope architecture in the Chloroflexi: A shifting frontline in a phylogenetic turf war |journal=Environmental Microbiology |volume=13 |issue=2 |pages=279–282 |bibcode=2011EnvMi..13..279S |doi=10.1111/j.1462-2920.2010.02339.x |pmid=20860732}}</ref> Two related phyla to the Chloroflexi, the [[TM7]] clade and the Ktedonobacteria, are also monoderms.<ref name="TM7">{{Cite journal |last1=Hugenholtz |first1=P. |last2=Tyson |first2=G.W. |last3=Webb |first3=R.I. |last4=Wagner |first4=A.M. |last5=Blackall |first5=L.L. |date=2001 |title=Investigation of Candidate Division TM7, a Recently Recognized Major Lineage of the Domain Bacteria with No Known Pure-Culture Representatives |journal=Applied and Environmental Microbiology |volume=67 |issue=1 |pages=411–419 |bibcode=2001ApEnM..67..411H |doi=10.1128/AEM.67.1.411-419.2001 |pmc=92593 |pmid=11133473}}</ref><ref name="Kt">{{Cite journal |last1=Cavaletti |first1=L. |last2=Monciardini |first2=P. |last3=Bamonte |first3=R. |last4=Schumann |first4=P. |last5=Rohde |first5=M. |last6=Sosio |first6=M. |last7=Donadio |first7=S. |date=2006 |title=New Lineage of Filamentous, Spore-Forming, Gram-Positive Bacteria from Soil |journal=Applied and Environmental Microbiology |volume=72 |issue=6 |pages=4360–4369 |bibcode=2006ApEnM..72.4360C |doi=10.1128/AEM.00132-06 |pmc=1489649 |pmid=16751552}}</ref>

Some Bacillota species are not gram-positive. The class Negativicutes, which includes ''[[Selenomonas]]'', are diderm and stain gram-negative.<ref name="pmid19667386" /> Additionally, a number of bacterial taxa (viz. [[Negativicutes]], [[Fusobacteriota]], [[Synergistota]], and [[Elusimicrobiota]]) that are either part of the phylum Bacillota or branch in its proximity are found to possess a diderm cell structure.<ref name="Sutcliffe, 2010" /><ref name="Gupta C" /><ref name="pmid19667386" /> However, a conserved signature indel (CSI) in the [[HSP60]] ([[GroEL]]) protein distinguishes all traditional phyla of gram-negative bacteria (e.g., [[Pseudomonadota]], [[Aquificota]], [[Chlamydiota]], [[Bacteroidota]], [[Chlorobiota]], "[[Cyanobacteria]]", [[Fibrobacterota]], [[Verrucomicrobiota]], [[Planctomycetota]], [[Spirochaetota]], [[Acidobacteriota]], etc.) from these other atypical diderm bacteria, as well as other phyla of monoderm bacteria (e.g., [[Actinomycetota]], [[Bacillota]], [[Thermotogota]], [[Chloroflexota]], etc.).<ref name="Gupta C" /> The presence of this CSI in all sequenced species of conventional LPS ([[lipopolysaccharide]])-containing gram-negative bacterial phyla provides evidence that these phyla of bacteria form a monophyletic clade and that no loss of the outer membrane from any species from this group has occurred.<ref name="Gupta C" />

== Pathogenicity ==
[[File:Actinomyces spp 01.jpg|thumb|320px|Colonies of a gram-positive pathogen of the oral cavity, ''[[Actinomyces]]'' sp.]]
In the classical sense, six gram-positive genera are typically pathogenic in humans. Two of these, ''[[Streptococcus]]'' and ''[[Staphylococcus]]'', are [[Coccus|cocci]] (sphere-shaped). The remaining organisms are [[bacilli]] (rod-shaped) and can be subdivided based on their ability to form [[endospore|spore]]s. The non-spore formers are ''[[Corynebacterium]]'' and ''[[Listeria]]'' (a coccobacillus), whereas ''[[Bacillus]]'' and ''[[Clostridium]]'' produce spores.<ref>{{Cite book |last1=Gladwin |first1=Mark |title=Clinical Microbiology Made Ridiculously Simple |last2=Trattler |first2=Bill |date=2007 |publisher=MedMaster |isbn=978-0-940780-81-1 |location=Miami, FL |pages=4–5}}</ref> The spore-forming bacteria can again be divided based on their [[Cellular respiration|respiration]]: ''Bacillus'' is a [[Facultative anaerobic organism|facultative anaerobe]], while ''Clostridium'' is an [[obligate anaerobe]].<ref>{{Cite conference |last1=Sahebnasagh |first1=R. |last2=Saderi |first2=H. |last3=Owlia |first3=P. |date=4–7 September 2011 |title=Detection of methicillin-resistant ''Staphylococcus aureus'' strains from clinical samples in Tehran by detection of the ''mecA'' and ''nuc'' genes |conference=The First Iranian International Congress of Medical Bacteriology |location=Tabriz, Iran}}</ref> Also, ''Rathybacter'', ''Leifsonia'', and ''Clavibacter'' are three gram-positive genera that cause plant disease. Gram-positive bacteria are capable of causing serious and sometimes fatal [[Neonatal infection|infections]] in newborn infants.<ref name="MacDonald2015">{{Cite book |last=MacDonald |first=Mhairi |title=Avery's Neonatology: Pathophysiology and Management of the Newborn |date=2015 |publisher=Wolters Kluwer |isbn=9781451192681 |location=Philadelphia, PA}} Access provided by the University of Pittsburgh.</ref> Novel species of clinically relevant gram-positive bacteria also include ''[[Catabacter hongkongensis]]'', which is an emerging pathogen belonging to [[Firmicutes|Bacillota]].<ref>{{Cite journal |last1=Lau |first1=S.K.P. |last2=McNabb |first2=A. |last3=Woo |first3=G.K.S. |last4=Hoang |first4=L. |last5=Fung |first5=A.M.Y. |last6=Chung |first6=L.M.W. |last7=Woo |first7=P.C.Y. |last8=Yuen |first8=K.-Y. |date=22 November 2006 |title=Catabacter hongkongensis gen. nov., sp. nov., Isolated from Blood Cultures of Patients from Hong Kong and Canada |journal=Journal of Clinical Microbiology |volume=45 |issue=2 |pages=395–401 |doi=10.1128/jcm.01831-06 |issn=0095-1137 |pmc=1829005 |pmid=17122022 |doi-access=free}}</ref>

==Bacterial transformation==
[[Transformation (genetics)|Transformation]] is one of three processes for [[horizontal gene transfer]], in which exogenous genetic material passes from a donor bacterium to a recipient bacterium, the other two processes being [[Bacterial conjugation|conjugation]] (transfer of [[Plasmid|genetic material]] between two bacterial cells in direct contact) and [[Transduction (genetics)|transduction]] (injection of donor bacterial DNA by a [[bacteriophage]] virus into a recipient host bacterium).<ref name="Johnston">{{Cite journal |last1=Johnston |first1=C. |last2=Martin |first2=B. |last3=Fichant |first3=G. |last4=Polard |first4=P |last5=Claverys |first5=J.P. |year=2014 |title=Bacterial transformation: distribution, shared mechanisms and divergent control |journal=Nature Reviews. Microbiology |volume=12 |issue=3 |pages=181–196 |doi=10.1038/nrmicro3199 |pmid=24509783 |s2cid=23559881}}</ref><ref name="Korotetskiy">{{Cite journal |vauthors=Korotetskiy I, Shilov S, Kuznetsova T, Kerimzhanova B, Korotetskaya N, Ivanova L, Zubenko N, Parenova R, Reva O |year=2023 |title=Analysis of Whole-Genome Sequences of Pathogenic Gram-Positive and Gram-Negative Isolates from the Same Hospital Environment to Investigate Common Evolutionary Trends Associated with Horizontal Gene Exchange, Mutations and DNA Methylation Patterning |journal=Microorganisms |volume=11 |issue=2 |page=323 |doi=10.3390/microorganisms11020323 |pmc=9961978 |pmid=36838287 |doi-access=free}}</ref> In transformation, the genetic material passes through the intervening medium, and uptake is completely dependent on the recipient bacterium.<ref name="Johnston" />

As of 2014 about 80 species of bacteria were known to be capable of transformation, about evenly divided between gram-positive and [[gram-negative bacteria]]; the number might be an overestimate since several of the reports are supported by single papers.<ref name="Johnston" />  Transformation among gram-positive bacteria has been studied in medically important species such as ''[[Streptococcus pneumoniae]]'', ''[[Streptococcus mutans]]'', ''[[Staphylococcus aureus]]'' and ''[[Streptococcus sanguinis]]'' and in gram-positive soil bacteria ''[[Bacillus subtilis]]'' and ''[[Bacillus cereus]]''.<ref name="Michod">{{Cite journal |last1=Michod |first1=R.E. |last2=Bernstein |first2=H. |last3=Nedelcu |first3=A.M. |year=2008 |title=Adaptive value of sex in microbial pathogens |journal=Infection, Genetics and Evolution |volume=8 |issue=3 |pages=267–285 |doi=10.1016/j.meegid.2008.01.002 |pmid=18295550|bibcode=2008InfGE...8..267M }}</ref>

== Orthography: Capitalization ==
<!--Please keep this text synched with that of [[Gram-positive bacteria#Orthographic note]].-->
The adjectives ''gram-positive'' and ''gram-negative'' derive from the surname of [[Hans Christian Gram]]; as [[Eponym#Orthographic conventions|eponymous adjectives]], their initial letter ''G'' can be either a capital or lower-case, depending on which [[style guide]] (e.g., that of the [[Centers for Disease Control and Prevention|CDC]]), if any, governs the document being written.<ref>{{Cite web |title=''Emerging Infectious Diseases'' Journal Style Guide |url=http://wwwnc.cdc.gov/eid/pages/preferred-usage.htm |website=CDC.gov |publisher=Centers for Disease Control and Prevention}}</ref>

== References ==
{{reflist}}

== External links ==
* {{NCBI-scienceprimer}}
* [http://opm.phar.umich.edu/localization.php?localization=Bacterial%20gram-positive%20plasma%20membrane 3D structures of proteins associated with plasma membrane of gram-positive bacteria]
* [http://opm.phar.umich.edu/localization.php?localization=Bacterial%20gram-positive%20outer%20membrane 3D structures of proteins associated with outer membrane of gram-positive bacteria]

{{Bacteria}}
{{Bacteria classification}}
{{Gram-positive firmicutes diseases}}

{{Authority control}}

[[Category:Gram-positive bacteria| ]]
[[Category:Staining]]
[[Category:Bacteriology]]