Editing Mesophile

{{Short description|Organism that thrives in moderate temperatures}}
A '''mesophile''' is an [[organism]] that grows best in moderate [[temperature]], neither too hot nor too cold, with an optimum growth range from {{convert|20| to|45|C}}.<ref>Willey, Joanne M., Linda Sherwood, Christopher J. Woolverton, and Lansing M. Prescott. Prescott, Harley, and Klein's Microbiology. New York: McGraw-Hill Higher Education, 2008. Print.</ref> The optimum growth temperature for these organisms is 37&nbsp;°C (about 99&nbsp;°F).<ref>{{Citation |last1=Schiraldi |first1=Chiara |title=Mesophilic Organisms |date=2016 |url=https://doi.org/10.1007/978-3-642-40872-4_1610-2 |encyclopedia=Encyclopedia of Membranes |pages=1–2 |editor-last=Drioli |editor-first=Enrico |place=Berlin, Heidelberg |publisher=Springer |language=en |doi=10.1007/978-3-642-40872-4_1610-2 |isbn=978-3-642-40872-4 |access-date=2022-05-22 |last2=De Rosa |first2=Mario |editor2-last=Giorno |editor2-first=Lidietta|url-access=subscription }}</ref> The term is mainly applied to [[microorganism]]s.  Organisms that prefer extreme environments are known as [[extremophiles]]. Mesophiles have diverse classifications, belonging to two [[domain (biology)|domain]]s: [[Bacteria]], [[Archaea]], and to [[kingdom (biology)|kingdom]] [[Fungi]] of domain [[Eukaryote|Eucarya]].  Mesophiles belonging to the domain Bacteria can either be [[gram-positive]] or [[gram-negative]]. Oxygen requirements for mesophiles can be [[aerobic organism|aerobic]] or [[anaerobic organism|anaerobic]]. There are three basic shapes of mesophiles: [[coccus]], [[Bacillus (shape)|bacillus]], and [[Spiral bacteria|spiral]].

==Habitat==
The habitats of mesophiles can include [[cheese]] and [[yogurt]]. They are often included during fermentation of [[beer]] and [[wine]] making.  Since normal human body temperature is 37 [[celsius|°C]], the majority of human [[pathogens]] are mesophiles, as are most of the organisms comprising the [[human microbiome]].

==Mesophiles vs. extremophiles==
Mesophiles are the opposite of [[extremophile]]s. Extremophiles that prefer cold environments are termed [[psychrophile|psychrophilic]], those preferring warmer temperatures are termed [[Thermophile|thermophilic or thermotropic]] and those thriving in extremely hot environments are [[hyperthermophile|hyperthermophilic]].
A genome-wide computational approach has been designed by Zheng, et al. to classify bacteria into mesophilic and thermophilic.<ref>{{cite journal|author1=Hao Zheng|author2=Hongwei Wu|title=Gene-centric association analysis for the correlation between the guanine-cytosine content levels and temperature range conditions of prokaryotic species|journal=BMC Bioinformatics|year=2010|volume=11|issue=Suppl 11|pages=S7|doi=10.1186/1471-2105-11-S11-S7|pmc=3024870|pmid=21172057 |doi-access=free }}</ref>

==Adaptations==
All bacteria have their own optimum environmental surroundings and temperatures in which they thrive. Many factors are responsible for a given organism's optimal temperature range, but evidence suggests that the expression of particular genetic elements ([[alleles]]) can alter the temperature-sensitive phenotype of the organism. A study published in 2016 demonstrated that mesophilic bacteria could be genetically engineered to express certain alleles from psychrophilic bacteria, consequently shifting the restrictive temperature range of the mesophilic bacteria to closely match that of the psychrophilic bacteria.<ref>{{cite journal|last1=Pankowski|first1=Jarosław A.|last2=Puckett|first2=Stephanie M.|last3=Nano|first3=Francis E.|title=Temperature Sensitivity Conferred by ligA Alleles from Psychrophilic Bacteria upon Substitution in Mesophilic Bacteria and a Yeast Species|journal=Applied and Environmental Microbiology|date=15 March 2016|volume=82|issue=6|pages=1924–1932|doi=10.1128/AEM.03890-15|issn=0099-2240|pmid=26773080|pmc=4784036|bibcode=2016ApEnM..82.1924P }}</ref>

Due to the less stable structure of mesophiles, it has reduced flexibility for [[protein synthesis]].<ref>Vijayabaskar, Mahalingam S. et al. "Construction of Energy Based Protein Structure Networks: Application in the Comparative Analysis of Thermophiles and Mesophiles" Biophysical Journal, Volume 98, Issue 3, 387a</ref> Mesophiles are not able to synthesize proteins in low temperatures. It is more sensitive to temperature changes, and the [[fatty acid]] composition of the [[membrane]] does not allow for much [[Membrane fluidity|fluidity]].<ref>{{cite journal | last1 = Li | first1 = K.Y. | last2 = Torres | first2 = J. A. | year = 1993 | title = EFFECTS of TEMPERATURE and SOLUTE ON the MINIMUM WATER ACTIVITY FOR GROWTH and TEMPERATURE CHARACTERISTIC of SELECTED MESOPHILES and PSYCHROTROPHS | journal = Journal of Food Processing and Preservation | volume = 17 | issue = 4| pages = 305–318 | doi = 10.1111/j.1745-4549.1993.tb00733.x | doi-access = free }}</ref> Decreasing the optimal temperature of 37&nbsp;°C to 0&nbsp;°C to 8&nbsp;°C leads to a gradual decrease in protein synthesis. [[Cold-induced proteins]] (CIPs) are induced during low temperatures, which then allows [[Cold-shock domain|cold-shock proteins]] (CSPs) to synthesize. The shift back to the optimal temperature sees an increase, indicating that mesophiles are highly dependent on temperature.<ref>Perrot, F., Hébraud, M., Junter, G.-A. and Jouenne, T. "Protein synthesis in Escherichia coli at 4°C. Electrophoresis." 2000, 21: 1625–1629. doi:10.1002/(SICI)1522-2683(20000501)21:8<1625::AID-ELPS1625>3.0.CO;2-4</ref> Oxygen availability also affects microorganism growth.<ref>Sinclair, N. A.; Stokes, J. L. " ROLE OF OXYGEN IN THE HIGH CELL YIELDS OF PSYCHROPHILES AND MESOPHILES AT LOW TEMPERATURES." The Journal of Bacteriology, 1963, Vol. 85(1), p.164 [Peer Reviewed Journal]</ref>

There are two explanations for thermophiles being able to survive at such high temperatures whereas mesophiles can not. The most evident explanation is that thermophiles are believed to have cell components that are relatively more stable than the cell components of mesophiles which is why thermophiles are able to live at higher temperatures than mesophiles.<ref name="Koffler 227–240">{{Cite journal|last=Koffler|first=Henry|title=Protoplasmic differences between mesophiles and thermophiles|date=2016-11-28|journal=Bacteriological Reviews|volume=21|issue=4|pages=227–240|issn=0005-3678|pmc=180904|pmid=13488883|doi=10.1128/MMBR.21.4.227-240.1957}}</ref> "A second school of thought, as represented by the writings of Gaughran (21) and Allen (3), believes that rapid resynthesis of damaged or destroyed cell constituents is the key to the problem of biological stability to heat."<ref name="Koffler 227–240"/>

==Oxygen requirements==
Due to the diversity of mesophiles, oxygen requirements greatly vary. [[Aerobic respiration]] requires the use of [[oxygen]] and anaerobic does not. There are three types of [[anaerobes]]. [[Facultative anaerobes]] grow in the absence of oxygen, using [[fermentation]] instead. During fermentation, sugars are converted to [[acids]], [[ethanol|alcohol]], or [[gas]]es. If there is oxygen present, it will use aerobic respiration instead. [[Obligate anaerobe]]s cannot grow in the presence of oxygen. [[Aerotolerant anaerobe]]s can withstand oxygen.

==Roles==
Microorganisms play an important role in [[decomposition]] of organic matter and [[mineralization (biology)|mineralization]] of [[nutrients]]. In [[aquatic ecosystem|aquatic]] environments, the diversity of the [[ecosystem]] allows for the diversity of mesophiles. The functions of each mesophile rely on the surroundings, most importantly temperature range.<ref>Ferroni, G.D., Kaminski, J.S. "Psychrophiles, psychrotrophs, and mesophiles in an environment which experiences seasonal temperature fluctuations." Canadian Journal of Microbiology, 1980, 26:1184-1191, 10.1139/m80-198</ref> [[Bacteria]] such as mesophiles and [[thermophile]]s are used in the [[cheesemaking]] due to their role in [[fermentation]]. "Traditional [[microbiologist]]s use the following terms to indicate the general (slightly arbitrary) optimum temperature for the growth of bacteria: [[psychrophile]]s (15–20 °C), mesophiles (30–37 °C), thermophiles (50–60 °C) and extreme thermophiles (up to 122 °C)".<ref>Johnson, Mark. "Mesophilic and Thermophilic Cultures Used in Traditional Cheesemaking." Cheese and Microbes. Washington: ASM Publishing. 2014. Web.</ref> Both mesophiles and thermophiles are used in cheesemaking for the same reason; however, they grow, thrive and die at different temperatures. [[Psychrotrophic bacteria]] contribute to dairy products spoiling, getting mouldy or going bad due to their ability to grow at lower temperatures such as in a refrigerator.

==Examples==
Some notable mesophiles include ''[[Listeria monocytogenes]]'', ''[[Staphylococcus aureus]]'', and ''[[Escherichia coli]]''. Other examples of [[species]] of mesophiles are ''[[Clostridium kluyveri]]'', ''[[Pseudomonas maltophilia]]'', ''[[Thiobacillus novellus]]'', ''[[Streptococcus pyogenes]]'', and ''[[Streptococcus pneumoniae]]''. Different types of diseases and infections typically have pathogens from mesophilic bacteria such as the ones listed above.

===''Listeria monocytogenes''===
''Listeria monocytogenes'' is a gram-positive bacterium. It is closely related to ''Bacillus'' and ''Staphylococcus''. It is a rod-shaped, facultative anaerobe that is motile by peritrichous [[flagella]]. ''L. monocytogenes'' motility is limited from 20&nbsp;°C to 25&nbsp;°C.<ref name=LISTERIA/> At the optimal temperature, it loses its motility. This bacterium is responsible for [[listeriosis]] which derives from contaminated food.<ref name=LISTERIA>Magalhã£Es, R. (2014). Listeria monocytogenes. 450-461.
</ref>

===''Staphylococcus aureus''===
''Staphylococcus aureus'' was first identified in 1880.<ref name=AUREUS/> It is responsible for different infections stemming from an injury. The bacterium overcomes the body's natural mechanisms. Long lasting infections of ''S. aureus'' includes [[pneumonia]], [[meningitis]], and [[osteomyelitis]]. ''S. aureus'' is commonly contracted in hospital settings.<ref name=AUREUS>Todd, E. (2014). Staphylococcus Aureus. 530-534</ref>

===''Escherichia coli''===
''Escherichia coli'' is a gram-negative, rod-shaped facultative anaerobic bacterium that does not produce [[spores]].<ref name=COLI/> The bacterium is a member of [[Enterobacteriaceae]]. It is capable of producing [[enterotoxins]] which are [[thermolabile]] or [[thermostable]].<ref name=COLI>Robinson, Richard K.. (2000). Encyclopedia of Food Microbiology, Volumes 1-3 - Escherichia Coli. Elsevier. Online version available at: http://app.knovel.com/hotlink/pdf/id:kt0051LGG3/encyclopedia-food-microbiology/escherichia-coli</ref> Other characteristics of ''E. coli'' are that it is [[oxidase]]-negative, [[citrate]]-negative, [[methyl red|methyl-red]] positive, and [[Voges-Proskauer]]-negative. To sum up ''E. coli'', it is a [[coliform]]. It is able to use [[glucose]] and [[acetate]] as a carbon source for fermentation. ''E. coli'' is commonly found in the [[Digestive system|gut]] of living organisms.<ref name=ROBINSON/> ''E. coli'' has many capabilities such as being a [[host (biology)|host]] for [[recombinant DNA]] and being a pathogen.<ref name=ROBINSON>Robinson, Richard K.. (2000). Encyclopedia of Food Microbiology, Volumes 1-3 - Escherichia Coli. Elsevier. Online version available at: http://app.knovel.com/hotlink/pdf/id:kt0051K7I1/encyclopedia-food-microbiology/ecology-bacteria-escherichia-3</ref>

==See also==
*[[Anaerobic digestion]]
*[[Mesophilic digester]]
*[[Mesophyte]]
*[[Neutrophile]]
*[[Reverse ecology]]

==References==
{{Reflist}}

[[Category:Anaerobic digestion]]
[[Category:Biodegradable waste management]]
[[Category:Biodegradation]]
[[Category:Microbial growth and nutrition]]