Editing Catalase (section)

== Clinical significance and application ==
[[Image:Wasserstoffperoxid.svg|left|thumb|Hydrogen peroxide]]
Catalase is used in the food industry for removing [[hydrogen peroxide]] from [[milk]] prior to [[cheese]] production.<ref name="urlCatalase - Worthington Enzyme Manual">{{cite web | url = http://www.worthington-biochem.com/CTL/default.html | title = Catalase | work = Worthington Enzyme Manual | publisher = Worthington Biochemical Corporation | access-date = 2009-03-01}}</ref> Another use is in food wrappers, where it prevents food from [[oxidation|oxidizing]].<ref name="urlRe: how is catalase used in industry?">{{cite web | url = http://madsci.org/posts/archives/mar99/921636249.Gb.r.html | title = Re: how is catalase used in industry? | author = Hengge A | date = 1999-03-16 | work = General Biology | publisher = MadSci Network | access-date = 2009-03-01 | archive-date = 2019-09-07 | archive-url = https://web.archive.org/web/20190907080521/http://madsci.org/posts/archives/mar99/921636249.Gb.r.html | url-status = dead }}</ref> Catalase is also used in the [[textile]] industry, removing hydrogen peroxide from fabrics to make sure the material is peroxide-free.<ref name="urltextile industry">{{cite web | url = http://www.p2pays.org/ref/11/10842.htm | title = textile industry | work = Case study 228 | publisher = International Cleaner Production Information Clearinghouse | access-date = 2009-03-01 | archive-url = https://web.archive.org/web/20081104083335/http://www.p2pays.org/ref/11/10842.htm | archive-date = 2008-11-04 | url-status = dead }}</ref>

A minor use is in [[contact lens]] hygiene – a few lens-cleaning products [[disinfection|disinfect]] the lens using a hydrogen peroxide solution; a solution containing catalase is then used to decompose the hydrogen peroxide before the lens is used again.<ref>{{US patent reference | number = 5521091 | y = 1996 | m = 05 | d = 28 | inventor = Cook JN, Worsley JL | title = Compositions and method for destroying hydrogen peroxide on contact lens }}</ref>

=== 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.

=== Bacterial virulence ===
[[Neutrophil]]s and other [[phagocyte]]s use peroxide to kill bacteria. The enzyme [[NADPH oxidase]] generates [[superoxide]] within the [[phagosome]], which is converted via hydrogen peroxide to other oxidising substances like [[hypochlorous acid]] which kill [[phagocytosed]] pathogens.<ref>{{cite journal | vauthors = Winterbourn CC, Kettle AJ, Hampton MB | title = Reactive Oxygen Species and Neutrophil Function | journal = Annual Review of Biochemistry | volume = 85 | issue = 1 | pages = 765–792 | date = June 2016 | pmid = 27050287 | doi = 10.1146/annurev-biochem-060815-014442 }}</ref> In individuals with [[chronic granulomatous disease]] (CGD), phagocytic peroxide production is impaired due to a defective NADPH oxidase system. Normal cellular metabolism will still produce a small amount of peroxide and this peroxide can be used to produce hypochlorous acid to eradicate the bacterial infection. However, if individuals with CGD are infected with catalase-positive bacteria, the bacterial catalase can destroy the excess peroxide before it can be used to produce other oxidising substances. In these individuals the pathogen survives and becomes a chronic infection. This chronic infection is typically surrounded by macrophages in an attempt to isolate the infection. This wall of macrophages surrounding a pathogen is called a [[granuloma]]. Many bacteria are catalase positive, but some are better catalase-producers than others. Some catalase-positive bacteria and fungi include: ''[[Nocardia]], [[Pseudomonas]], [[Listeria]], [[Aspergillus]], [[Candida albicans|Candida]], [[Escherichia coli|E. coli]], [[Staphylococcus]], [[Serratia]], [[Burkholderia cepacia complex|B. cepacia]]'' and ''[[Helicobacter pylori|H. pylori]]''.<ref>{{Cite book|title=First aid for the USMLE step 1 2017: a student-to-student guide |isbn=978-1-259-83762-3 |edition=27th |location=New York |publisher=McGraw-Hill Education |oclc=986222844| vauthors = Le T, Bhushan V, Sochat M, Kallianos K, Chavda Y, Zureick AH |date = 2017-01-06}}</ref>

=== Acatalasia ===
[[Acatalasia]] is a condition caused by homozygous mutations in CAT, resulting in a lack of catalase. Symptoms are mild and include oral ulcers. A heterozygous CAT mutation results in lower, but still present catalase.<ref>{{cite web |title=OMIM Entry - # 614097 - ACATALASEMIA |url=http://www.omim.org/entry/614097 |website=www.omim.org |language=en-us}}</ref>

=== Gray hair ===
Low levels of catalase may play a role in the [[Human hair color#Gray and white hair|graying]] process of human hair. Hydrogen peroxide is naturally produced by the body and broken down by catalase. Hydrogen peroxide can accumulate in hair follicles and if catalase levels decline, this buildup can cause oxidative stress and graying.<ref>{{Cite web |title=Gray hair cure? Scientists find root cause of discoloration |url=http://www.nbcnews.com/healthmain/gray-hair-cure-scientists-find-root-cause-discoloration-6C9802771 |access-date=2022-07-31 |website=NBC News |date=6 May 2013 |language=en}}</ref> These low levels of catalase are associated with old age. Hydrogen peroxide interferes with the production of [[melanin]], the pigment that gives hair its color.<ref name="ScienceDaily_Grey_Hair">{{cite web | url = https://www.sciencedaily.com/releases/2009/02/090223131123.htm | title = Why Hair Turns Gray Is No Longer A Gray Area: Our Hair Bleaches Itself As We Grow Older | date = 2009-02-24 | work = Science News | publisher = ScienceDaily | access-date = 2009-03-01}}</ref><ref name="pmid19237503">{{cite journal | vauthors = Wood JM, Decker H, Hartmann H, Chavan B, Rokos H, Spencer JD, Hasse S, Thornton MJ, Shalbaf M, Paus R, Schallreuter KU | title = Senile hair graying: H2O2-mediated oxidative stress affects human hair color by blunting methionine sulfoxide repair | journal = FASEB Journal | volume = 23 | issue = 7 | pages = 2065–2075 | date = July 2009 | pmid = 19237503 | doi = 10.1096/fj.08-125435 | doi-access = free | arxiv = 0706.4406 | s2cid = 16069417 }}</ref>