Gram-positive

Image:Gram Stain Anthrax.jpg

Gram-positive bacteriaare those that are stained dark blue or violet by gram staining, in contrast to Gram-negativebacteria, which cannot retain the stain, instead taking up the counterstainand appearing red or pink. The stain is caused by a high amount of peptidoglycanin the cell wall, which typically, but not always lacks the secondary membrane and lipopolysaccharidelayer found in Gram-negative bacteria.

In the original bacterial phyla, the gram-positive forms made up the phylumFirmicutes, a name now used for the largest group. It includes many well-known genera such as Bacillus, Listeria, Staphylococcus, Streptococcus, Enterococcus, and Clostridium. It has also been expanded to include the Mollicutes, bacteria like Mycoplasma that lack cell walls and so cannot be stained by Gram, but are derived from such forms.

The actinobacteriaare another major group of gram-positive bacteria; they and the Firmicutes are referred to as the high and low G+C groups based on the guanosineand cytosinecontent of their DNA. If the second membrane is a derived condition, the two may have been basal among the bacteria; otherwise they are probably a relatively recent monophyletic group. They have been considered as possible ancestors for the archaeansand eukaryotes, both because they are unusual in lacking the second membrane and because of various biochemical similarities such as the presence of sterols.

The Deinococcus-Thermusbacteria also have gram-positive stains, although they are structurally similar to gram-negative bacteria.

Both gram-positive and gram-negative bacteria may have a membrane called an S-layer. In gram-negative bacteria, the S-layer is directly attached to the outer membrane. In gram-positive bacteria, the S-layer is attached to the peptidoglycanlayer.

References

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 |then=Medical Microbiology, 4th ed.
 |else=Medical Microbiology, 4th ed.

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 }}The University of Texas Medical Branch at Galveston

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 |then=. ISBN 0-9631172-1-1

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• {{qif

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   }}
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   |then=Madigan, Michael; Martinko, John (editors)
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• This article contains material from the Science Primer published by the NCBI, which, as a US government publication, is in the public domainat http://www.ncbi.nlm.nih.gov/About/disclaimer.html.cs:Grampozitivní bakterie

es:Bacteria Gram-positiva fr:Gram positif nl:Gram-positief pl:Bakterie Gram-dodatnie fi:Grampositiivinen bakteeri zh:??????

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Gram-positive Wikipedia article Gram-positive.