Human interactions with microbes

Human interactions with microbesinclude both practical and symbolic uses ofmicrobes, and negative interactions in the form of human, domestic animal, and crop diseases.
Practical use of microbes began in ancient times withfermentation in food processing;bread,beerandwinehave been produced byyeastsfrom the dawn of civilisation, such as inancient Egypt. More recently, microbes have been used in activities frombiological warfareto the production of chemicals byfermentation, as industrial chemists discover how to manufacture a widening variety of organic chemicals includingenzymesand bioactive molecules such ashormonesandcompetitive inhibitorsfor use as medicines. Fermentation is used, too, to produce substitutes for fossil fuels in forms such asethanolandmethane;fuels may also be produced by algae. Anaerobic microorganisms are important insewage treatment. In scientific research, yeasts and the bacteriumEscherichia coliserve asmodel organismsespecially ingeneticsand related fields.
On the symbolic side, an early poem about brewing is theSumerian"Hymn to Ninkasi", from 1800 BC. In theMiddle Ages,Giovanni Boccaccio'sThe DecameronandGeoffrey Chaucer'sThe Canterbury Tales: addressed people's fear of deadly contagion and the moral decline that could result. Novelists have exploited theapocalyptic possibilitiesofpandemicsfromMary Shelley's 1826The Last ManandJack London's 1912The Scarlet Plagueonwards.Hilaire Bellocwrote a humorous poem to "The Microbe" in 1912. Dramatic plagues and mass infection have formed the story lines of manyHollywoodfilms, starting withNosferatuin 1922. In 1971,The Andromeda Straintold the tale of anextraterrestrial microbethreatening life on Earth.MicrobiologistssinceAlexander Fleminghave used coloured orfluorescingcolonies of bacteria to create miniature artworks.
Microorganisms such asbacteriaandvirusesare important aspathogens, causing disease to humans,crop plants, anddomestic animals.
Cultureconsists of thesocial behaviourandnormsfound inhumansocietiesand transmitted throughsocial learning.Cultural universalsin all human societies include expressive forms likeart,music,dance,ritual,religion, andtechnologiesliketool usage,cooking,shelter, andclothing. The concept ofmaterial culturecovers physical expressions such as technology, architecture and art, whereas immaterial culture includes principles ofsocial organization,mythology,philosophy,literature, andscience.This article describes the roles played by microorganisms in human culture.
Since microbes were not known until theEarly Modernperiod, they appear in earlier literature indirectly, through descriptions ofbakingandbrewing. Only with the invention of themicroscope, as used byRobert Hookein his 1665 bookMicrographia,and byAntonie van Leeuwenhoekin the 1670s,thegerm theory of disease, and progress inmicrobiologyin the 19th century were microbes observed directly, identified as living organisms, and put to use on a scientific basis.The same knowledge also allowed microbes to appear explicitly in literature and the arts.
Controlledfermentationwith microbes inbrewing,wine making,baking,picklingand cultureddairy productssuch asyogurtandcheese, is used to modify ingredients to makefoodswith desirable properties. Theprincipal microbes involvedareyeasts, in the case of beer, wine, and ordinarybread; andbacteria, in the case ofanaerobicallyfermentedvegetables,dairy products, andsourdoughbread. The cultures variously provide flavour and aroma, inhibit pathogens, increase digestibility and palatability, make bread rise, reduce cooking time, and create useful products includingalcohol,organic acids,vitamins,amino acids, andcarbon dioxide. Safety is maintained with the help offood microbiology.
Oxidative sewage treatment processes rely on microorganisms to oxidise organic constituents. Anaerobic microorganisms reduce sludge solids producingmethanegas and a sterile mineralised residue. Inpotable watertreatment, one method, theslow sand filter, employs a complex gelatinous layer composed of a wide range of microorganisms to remove both dissolved and particulate material from raw water.
Microorganisms are used in fermentation to produce ethanol,and inbiogasreactors to produce methane.Scientists are researching the use ofalgae to produce liquid fuels,and bacteria to convert various forms of agricultural and urban waste intousable fuels.
Microorganisms are used for many commercial and industrial purposes, including the production of chemicals,enzymesand other bioactive molecules, often throughprotein engineering. For example,acetic acidis produced by the  bacteriumAcetobacter aceti, whilecitric acidis produced by the fungusAspergillus niger. Microorganisms are used to prepare a widening range of bioactive molecules and enzymes. For example,Streptokinaseproduced by the bacteriumStreptococcusand modified bygenetic engineeringis usedto remove clotsfrom the blood vessels of patients who have suffered aheart attack.Cyclosporin Ais animmunosuppressive agentinorgan transplantation, whilestatinsproduced by the yeastMonascus purpureusserve asblood cholesterollowering agents,competitively inhibitingthe enzyme that synthesizes cholesterol.
Microorganisms are essential tools inbiotechnology,biochemistry,genetics, andmolecular biology. The yeasts brewer's yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe) are importantmodel organismsin science, since they are simpleeukaryotesthat can be grown rapidly in large numbers and are easily manipulated.They are particularly valuable in genetics,genomicsandproteomics, for example inprotein production.The easily cultured gut bacteriumEscherichia coli, aprokaryote, is similarly widely used as a model organism.
Microbes can form anendosymbioticrelationship with larger organisms. For example, the bacteria that live within the human digestive systemcontribute to human healththrough gut immunity, the synthesis ofvitaminssuch asfolic acidandbiotin, and the fermentation of complex indigestiblecarbohydrates.Future drugs and food chemicals may need to be tested on thegut microbiota; it is already clear thatprobioticsupplements can promote health, and that gut microbes are affected by both diet and medicines.
Pathogenic microbes, andtoxinsthat they produce, have been developed as possible agents of warfare.Crude forms of biological warfare have been practiced since antiquity.In the 6th century BC, theAssyrianspoisoned enemy wells with afungussaid to render the enemy delirious.In 1346, the bodies ofMongolwarriors of theGolden Hordewho had died of plague were thrown over the walls of thebesieged Crimean city of Kaffa, possibly assisting the spread of theBlack Deathinto Europe.Advances inbacteriologyin the 20th century increased the sophistication of possiblebio-agentsin war. Biological sabotage—in the form ofanthraxandglanders—was undertaken on behalf of theImperial Germangovernment duringWorld War I, with indifferent results.InWorld War II, Britain weaponisedtularemia,anthrax,brucellosis, andbotulismtoxins, but never used them.The USA similarly explored biological warfare agents,developing anthrax spores,brucellosis, and botulism toxins for possible military use.Japan developed biological warfare agents, with the use ofexperiments on human prisoners, and was about to use them when the war ended.
Being very small, and unknown until the invention of themicroscope, microbes do not feature directly in art or literature beforeEarly Moderntimes (though they appear indirectly in works about brewing and baking), whenAntonie van Leeuwenhoekobserved microbes in water in 1676; his results were soon confirmed byRobert Hooke.A few major diseases such astuberculosisappearin literature, art, film, opera and music.
The literary possibilities ofpost-apocalyptic storiesaboutpandemics(worldwide outbreaks of disease) have been explored in novels and films fromMary Shelley's 1826The Last ManandJack London's 1912The Scarlet Plagueonwards. Medieval writings that deal with plague includeGiovanni Boccaccio'sThe DecameronandGeoffrey Chaucer'sThe Canterbury Tales: both treat the people's fear of contagion and the resulting moral decline, as well as bodily death.
The making of beer has been celebrated in verse since the time of AncientSumeria, c. 1800 BC, when the "Hymn toNinkasi" was inscribed on a clay tablet. Ninkasi,tutelary goddessof beer, and daughter of the creator Enki and the "queen of thesacred lake" Ninki, "handles thedoughand with a big shovel, mixing in a pit, the bappir with [date] honey, ... waters themaltset on the ground, ... soaks the malt in a jar, ... spreads the cookedmashon large reed mats, coolness overcomes, ... holds with both hands the great sweetwort,brewingit with honey".
Wine is a frequent topic inEnglish literature, from the spiced French and Italian "ypocras", "claree", and "vernage" in Chaucer'sThe Merchant's Taleonwards.William Shakespeare'sFalstaffdrank Spanish "sherris sack", in contrast toSir Toby Belch's preference for "canary". Wine references in later centuries branch out to more winegrowing regions.
The Microbeis a humorous 1912 poem byHilaire Belloc, starting with the lines "The microbe is so very small / You cannot make him out at all,/ But many sanguine people hope / To see him through a microscope.Microbes and Manis an admired "classic"book, first published in 1969, by the "father figure of British microbiology"John Postgateon the whole subject of microorganisms and their relationships with humans.
Microbes feature in many highly dramatized films.Hollywoodwas quick to exploit the possibilities of deadly disease, mass infection and drastic government reaction, starting as early as 1922 withNosferatu, in which aDracula-like figure,Count Orlok, sleeps in unhallowed ground contaminated with theBlack Death, which he brings with him wherever he goes. Another classic film,Ingmar Bergman's 1957The Seventh Seal, deals with the plague theme very differently, with thegrim reaperdirectly represented by an actor in a hood. More recently, the 1971The Andromeda Strain, based ona novelbyMichael Crichton, portrayed an extraterrestrial microbe contaminating the Earth.
"A Very Cellular Song," a song from the Britishpsychedelic folkbandThe Incredible String Band's 1968 albumThe Hangman's Beautiful Daughter,is told partially from the point of view of anamoeba, aprotistan.TheCOVID-19 pandemicinspired several songs and albums.
Microbial artis the creation of artworks by culturing bacteria, typically onagar plates, to form desired patterns. These may be chosen tofluoresceunder ultraviolet light in different colours.Alexander Fleming, the discoverer ofpenicillin, created "germ paintings" using different species of bacteria that were naturally pigmented in different colours.
An instance of aprotistin an artwork is the artistLouise Bourgeois'sbronzesculptureAmoeba. It has a whitepatinaresembling plaster, and was designed in 1963–5, based on drawings of a pregnant woman's belly that she made as early as the 1940s. According to theTate Gallery, the work "is a roughly modelled organic form, its bulges and single opening suggesting a moving, living creature in the stages of evolution."
Microorganisms are the causative agents (pathogens) in many infectious diseases of humans and domestic animals.Pathogenic bacteriacause diseases such asplague,tuberculosisandanthrax. Protozoa cause diseases includingmalaria,sleeping sickness,dysenteryandtoxoplasmosis. Microscopic fungi cause diseases such asringworm,candidiasisandhistoplasmosis.Pathogenic virusescause diseases such asinfluenza,yellow feverandAIDS.
The practice ofhygienewas created to preventinfectionorfoodspoiling by eliminating microbes, especially bacteria, from the surroundings.
Microorganisms includingbacteria,fungi, andvirusesare important as plantpathogens, causing disease tocrop plants. Fungi cause serious crop diseases such asmaizeleaf rust,wheatstem rust, and powdery mildew. Bacteria cause plant diseases including leaf spot and crown galls. Viruses cause plant diseases such as leaf mosaic.TheoomycetePhytophthora infestanscauses potato blight, contributing to theGreat Irish Famineof the 1840s.
Thetulip breaking virusplayed a role in thetulip maniaof theDutch Golden Age. The famous Semper Augustus tulip, in particular, owed its striking pattern to infection with the plant disease, a kind ofmosaic virus, making it the most expensive of all the tulip bulbs sold.