Editing Microorganism (section)

==Human health==

=== Human gut flora ===
{{Further|Human microbiota |Human Microbiome Project}}

Microorganisms can form an [[Endosymbiont|endosymbiotic]] relationship with other, larger organisms. For example, [[Microbial symbiosis and immunity|microbial symbiosis]] plays a crucial role in the immune system. The microorganisms that make up the [[gut flora]] in the [[gastrointestinal tract]] contribute to gut immunity, synthesize [[vitamin]]s such as [[folic acid]] and [[biotin]], and ferment complex indigestible [[carbohydrate]]s.<ref>{{Cite journal |author=O'Hara, A. |author2=Shanahan, F. | title=The gut flora as a forgotten organ | journal=EMBO Rep | volume=7 | issue=7 | pages=688–693 | year=2006 | pmid=16819463 | doi=10.1038/sj.embor.7400731 | pmc=1500832}}</ref> Some microorganisms that are seen to be beneficial to health are termed [[probiotic]]s and are available as [[dietary supplement]]s, or [[food additive#Fortifying agents|food additives]].<ref name=who>{{cite web|last1=Schlundt |first1=Jorgen |title=Health and Nutritional Properties of Probiotics in Food including Powder Milk with Live Lactic Acid Bacteria |url=https://www.who.int/foodsafety/publications/fs_management/en/probiotics.pdf |work=Report of a Joint FAO/WHO Expert Consultation on Evaluation of Health and Nutritional Properties of Probiotics in Food Including Powder Milk with Live Lactic Acid Bacteria |publisher=FAO / WHO |access-date=17 December 2012 |url-status=dead |archive-url=https://web.archive.org/web/20121022161702/http://www.who.int/foodsafety/publications/fs_management/en/probiotics.pdf |archive-date=22 October 2012 }}</ref>

===Disease===
{{Main|Pathogen|Germ theory of disease}}
{{Further|Medical microbiology|Parasite}}
[[File:Plasmodium.jpg|thumb|upright|The [[eukaryotic]] [[parasite]] ''[[Plasmodium falciparum]]'' (spiky blue shapes), a causative agent of [[malaria]], in human blood]]

Microorganisms are the causative agents ([[pathogen]]s) in many [[Infection|infectious diseases]]. The organisms involved include [[pathogenic bacteria]], causing diseases such as [[bubonic plague|plague]], [[tuberculosis]] and [[anthrax]]; [[protozoa]]n [[parasite]]s, causing diseases such as [[malaria]], [[African trypanosomiasis|sleeping sickness]], [[dysentery]] and [[toxoplasmosis]]; and also fungi causing diseases such as [[ringworm]], [[candidiasis]] or [[histoplasmosis]]. However, other diseases such as [[influenza]], [[yellow fever]] or [[AIDS]] are caused by [[pathogenic viruses]], which are not usually classified as living organisms and are not, therefore, microorganisms by the strict definition. No clear examples of archaean pathogens are known,<ref>{{Cite journal |author=Eckburg, P. |author2=Lepp, P. |author3=Relman, D. |title=Archaea and Their Potential Role in Human Disease |journal=[[Infect Immun]] |volume=71 |issue=2 |pages=591–596 |year=2003 |pmid=12540534 | doi=10.1128/IAI.71.2.591-596.2003 |pmc=145348}}</ref> although a relationship has been proposed between the presence of some archaean methanogens and human [[periodontal disease]].<ref>{{Cite journal |author=Lepp, P. |author2=Brinig, M. |author3=Ouverney, C. |author4=Palm, K. |author5=Armitage, G. |author6=Relman, D. |title=Methanogenic Archaea and human periodontal disease | doi= 10.1073/pnas.0308766101 | journal=[[Proc Natl Acad Sci USA]] |volume=101 |issue=16 |pages=6176–6181 |year=2004 |pmid=15067114 |pmc=395942|bibcode=2004PNAS..101.6176L |doi-access=free }}</ref> Numerous microbial pathogens are capable of sexual processes that appear to facilitate their survival in their infected host.<ref>{{cite journal | author = Bernstein H. |last2=Bernstein |first2=C. |last3=Michod |first3=R. E. | date = Jan 2018 | title = Sex in microbial pathogens | journal = Infect Genet Evol | volume = 57 | pages = 8–25 | doi = 10.1016/j.meegid.2017.10.024 | pmid = 29111273 | doi-access = free | bibcode = 2018InfGE..57....8B }}</ref>

=== Hygiene ===
{{Main|Hygiene |Food microbiology}}

Hygiene is a set of practices to avoid [[infection]] or [[food spoilage]] by eliminating microorganisms from the surroundings. As microorganisms, in particular bacteria, are found virtually everywhere, [[pathogen|harmful microorganisms]] may be reduced to acceptable levels rather than actually eliminated. In food preparation, microorganisms are reduced by [[Food preservation|preservation]] methods such as cooking, cleanliness of utensils, short storage periods, or by low temperatures. If complete sterility is needed, as with surgical equipment, an [[autoclave]] is used to kill microorganisms with heat and pressure.<ref>{{cite web |url=https://www.who.int/topics/hygiene/en/|archive-url=https://web.archive.org/web/20040823014256/http://www.who.int/topics/hygiene/en/|url-status=dead|archive-date=23 August 2004|title=Hygiene |publisher=World Health Organization (WHO) |access-date=18 May 2017}}</ref><ref>{{cite web |url=https://www.who.int/foodsafety/consumer/5keys/en/ |archive-url=https://web.archive.org/web/20031207063202/http://www.who.int/foodsafety/consumer/5keys/en/ |url-status=dead |archive-date=7 December 2003 |title=The Five Keys to Safer Food Programme |publisher=World Health Organization |access-date=23 May 2021}}</ref>