[[Berkas:Anthonie van Leeuwenhoek (1632-1723). Natuurkundige te Delft Rijksmuseum SK-A-957.jpeg |jmpl|kiri|160px|[[Antony van Leeuwenhoek]], orang pertama yang mengamati bakteri melalui mikroskop.]]
Sebelum ditemukannya [[mikroskop]], bakteriBakteri merupakan organisme yangmikroskopik sehingga sulit dideteksi, terutama sebelum ditemukannya [[mikroskop]]. Organisme ini pertama kali diamati pada tahun 1676 oleh [[Antony van Leeuwenhoek]], pedagang dan ilmuwan Belanda. Ia menggunakan mikroskop berlensa tunggal yang dirancangnya sendiri.<ref>{{cite journal | last = Porter|first= J.R. | title = Antony van Leeuwenhoek: tercentenary of his discovery of bacteria | journal = Bacteriological Reviews | volume = 40 | issue = 2 | pages = 260–269 | date = Juni 1976 | pmid = 786250 | pmc = 413956 | doi = 10.1128/mmbr.40.2.260-269.1976 }}</ref> Leeuwenhoek lalu menerbitkan pengamatannya dalam serangkaian surat kepada [[Royal Society|Royal Society of London]],<ref>{{cite journal |doi=10.1098/rstl.1684.0030 |last=van Leeuwenhoek|first=A.|title=An abstract of a letter from Mr. Anthony Leevvenhoek at Delft, dated Sep. 17, 1683, Containing Some Microscopical Observations, about Animals in the Scurf of the Teeth, the Substance Call'd Worms in the Nose, the Cuticula Consisting of Scales |journal=Philosophical Transactions |volume=14 |pages=568–574 |year=1684 |issue=155–166|bibcode=1684RSPT...14..568L |doi-access=free }}</ref><ref>{{cite journal |last=van Leeuwenhoek|first=A.|title=Part of a Letter from Mr Antony van Leeuwenhoek, concerning the Worms in Sheeps Livers, Gnats, and Animalcula in the Excrements of Frogs |journal=Philosophical Transactions |volume=22 |pages=509–18 |year=1700 |doi=10.1098/rstl.1700.0013 |issue=260–276|bibcode=1700RSPT...22..509V |doi-access=free }}</ref><ref>{{cite journal |last=van Leeuwenhoek|first=A.|title=Part of a Letter from Mr Antony van Leeuwenhoek, F.R.S. concerning Green Weeds Growing in Water, and Some Animalcula Found about Them |journal=Philosophical Transactions |volume=23 |pages=1304–11|year = 1702 |doi=10.1098/rstl.1702.0042 |issue=277–288|bibcode=1702RSPT...23.1304V |s2cid=186209549 }}</ref> yang kemudian dipublikasikan dalam bahasa Inggris pada 1684.{{sfn|Madigan dkk.|2015|p=13}} Bakteri merupakan objek yang berada dalam batas yang bisa dilihat oleh lensa sederhana Leeuwenhoek dan tak ada orang lain yang bisa melihatnya selama lebih dari satu abad.<ref>{{cite book | last = Asimov |first = Isaac | author-link = Isaac Asimov | year = 1982 | title = Asimov's Biographical Encyclopedia of Science and Technology | edition = 2 | location = Garden City, NY | publisher = Doubleday and Company | page = [https://archive.org/details/asimovsbiographi00asim/page/143 143]}}</ref> Leeuwenhoek juga mengamati [[protozoa]], yang kesemuanya ia sebut sebagai "hewan kecil".<ref>{{Cite journal|last=Lane|first=Nick|date=19 April 2015|title=The unseen world: reflections on Leeuwenhoek (1677) ‘Concerning little animals’|url=https://royalsocietypublishing.org/doi/10.1098/rstb.2014.0344|journal=Philosophical Transactions of the Royal Society B: Biological Sciences|language=|volume=370|issue=1666|pages=20140344|doi=10.1098/rstb.2014.0344|issn=0962-8436|pmc=PMC4360124|pmid=25750239}}</ref>
[[Christian Gottfried Ehrenberg]], ilmuwan Jerman, memperkenalkan kata ''bacterium'' pada tahun 1838.<ref>{{Cite book|last=Ehrenberg|first=Christian Gottfried|last2=Carlgren|first2=Oskar|last3=Hemprich|first3=W. F.|last4=Hilgendorf|first4=Franz|last5=Klug|first5=Fr.|last6=Klug|first6=Fr.|last7=Martens|first7=Eduard von|last8=Matschie|first8=Paul|last9=Schumann|first9=K.|date=1828|url=http://www.biodiversitylibrary.org/bibliography/107403|title=Symbolae physicae, seu, Icones et descriptiones corporum naturalium novorum aut minus cognitorum : quae ex itineribus per Libyam Aegyptum Nubiam Dongalam Syriam Arabiam et Habessiniam publico institutis sumptu Friderici Guilelmi Hemprich et Christiani Godofredi Ehrenberg : studio annis MDCCCXX-MDCCCXXV redierunt|chapter=Symbolae Physicae: Animalia Evertebrata Exclusis Insectis|location=Berolini|publisher=Ex Officina Academica, venditur a Mittlero|doi=10.5962/bhl.title.107403|page=[https://www.biodiversitylibrary.org/page/48517135#page/16/mode/1up 16]}}</ref><ref>{{Cite journal|last=Breed|first=Robert S.|last2=Conn|first2=H. J.|date=1936|title=The Status of the Generic Term Bacterium Ehrenberg 1828*|url=https://jb.asm.org/content/31/5/517|journal=Journal of Bacteriology|language=|volume=31|issue=5|pages=517–518|doi=10.1128/JB.31.5.517-518.1936|issn=0021-9193}}</ref> Kata ini berasal dari [[romanisasi]] [[bahasa Yunani]] βακτηριον (''bakterion''),<ref>{{Cite book|last=Liddell|first=Henry George|last2=Scott|first2=Robert|date=1940|title=A Greek–English Lexicon|work=Perseus Project|location=Oxford|publisher=Clarendon Press|chapter=βακτήριον|chapter-url=http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0057:entry=bakthri/a|url-status=live}}</ref> bentuk [[diminutif]] dari [[wikt:βακτηρία|βακτηρία]] (''bakteria'') yang memiliki arti "batang" atau "tongkat" karena bakteri pertama yang ditemukan [[basilus|berbentuk batang]].<ref>{{Cite web|title=Bacterium|url=https://www.lexico.com/definition/bacterium|website=Lexico|access-date=15 Mei 2021|archive-date=2021-05-15|archive-url=https://web.archive.org/web/20210515141321/https://www.lexico.com/definition/bacterium|dead-url=yes}}</ref><ref>{{OEtymD|Bacteria}}</ref>
