Editing Catalase (section)

=== Bacterial identification (catalase test) ===
[[Image:Catalase reaction.jpg|300px|thumb|Positive catalase reaction]]
The catalase test is one of the three main tests used by microbiologists to identify species of bacteria. If the bacteria possess catalase (i.e., are catalase-positive), bubbles of oxygen are observed when a small amount of bacterial [[Isolation (microbiology)|isolate]] is added to hydrogen peroxide. The catalase test is done by placing a drop of hydrogen peroxide on a [[microscope slide]]. An applicator stick is touched to the colony, and the tip is then smeared onto the hydrogen peroxide drop.
* If the mixture produces bubbles or froth, the organism is said to be 'catalase-positive'. [[Staphylococcus|Staphylococci]]<ref name="urlBSCI 424 Pathogenic Microbiology -- Bacterial Pathogen List">{{cite web | url = http://www.life.umd.edu/classroom/bsci424/pathogendescriptions/PathogenList.htm | title = Bacterial Pathogen List | author = Rollins DM | date = 2000-08-01 | work = BSCI 424 Pathogenic Microbiology | publisher = University of Maryland | access-date = 2009-03-01}}</ref> and [[Micrococcus|Micrococci]]<ref name="urlBiochemical Tests">{{cite web | url = http://www.mc.maricopa.edu/~johnson/labtools/Dbiochem/cat.html | title = Catalase Production | author = Johnson M | work = Biochemical Tests | publisher = Mesa Community College | access-date = 2009-03-01 | url-status = dead | archive-url = https://web.archive.org/web/20081211073437/http://www.mc.maricopa.edu/~johnson/labtools/Dbiochem/cat.html | archive-date = 2008-12-11 }}</ref> are catalase-positive. Other catalase-positive organisms include ''[[Listeria]], [[Corynebacterium diphtheriae]], [[Burkholderia cepacia]], [[Nocardia]]'', the family [[Enterobacteriaceae]] (''[[Citrobacter]], [[Escherichia coli|E. coli]], [[Enterobacter]], [[Klebsiella]], [[Shigella]], [[Yersinia]], [[Proteus (bacterium)|Proteus]], [[Salmonella]], [[Serratia]]''), ''[[Pseudomonas]]'', ''[[Mycobacterium tuberculosis]], [[Aspergillus]]'', [[Cryptococcus (fungus)|''Cryptococcus'']], and ''[[Rhodococcus equi]]''.
* If not, the organism is 'catalase-negative'. ''[[Streptococcus]]''<ref name="urlStreptococcus pneumoniae and Staphylococci">{{cite web | url = http://pathmicro.med.sc.edu/fox/strep-staph.htm | title = Streptococcus pneumoniae and Staphylococci | author = Fox A | publisher = University of South Carolina | access-date = 2009-03-01}}</ref> and ''[[Enterococcus]]'' spp. are catalase-negative.

While the catalase test alone cannot identify a particular organism, it can aid identification when combined with other tests such as antibiotic resistance. The presence of catalase in bacterial cells depends on both the growth condition and the medium used to grow the cells.

[[Capillary tube]]s may also be used. A small sample of bacteria is collected on the end of the capillary tube, without blocking the tube, to avoid [[false negative]] results. The opposite end is then dipped into hydrogen peroxide, which is drawn into the tube through [[capillary action]], and turned upside down, so that the bacterial sample points downwards. The hand holding the tube is then tapped on the bench, moving the hydrogen peroxide down until it touches the bacteria. If bubbles form on contact, this indicates a positive catalase result. This test can detect catalase-positive bacteria at concentrations above about 10<sup>5</sup> cells/mL,<ref>{{Cite book|url=https://books.google.com/books?id=_orkBwAAQBAJ&pg=PA35|title=Fisheries Processing: Biotechnological applications| vauthors = Martin AM |date=2012-12-06|publisher=Springer Science & Business Media|isbn=9781461553038|language=en}}</ref> and is simple to use.