How did the Petri dish very first come into being and was Richard Julius Petri really the male responsible because that its creation? Stephen Mortlock delves into the annals the microbiology.

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Scientists usage them every day and discard them without a second thought. They room ubiquitous, disposable and also often disregarded. Castle are, the course, Petri dishes. These popular shallow and lidded plastic bowl haves been provided to grow bacterial cultures for plenty of years, serving a range of uses, such as testing the virulence that bacterial cultures or examining the efficacy the antibiotic drugs in development. 

When the scarlet fever bacteria, Streptococcus pyogenes, was discovered to prosper in milk in the 1920s, researches were performed making use of Petri dishes to show the prominence of keeping milk refrigerated 1. Other studies showed exactly how Petri dishes, once inoculated v bacteria, might be incubated in aerobic, micro-aerophilic and also anaerobic problems to grow a range of organisms or by including a steel cover to stop moisture loss and the dehydration that the media 2-4. 

The plates, originally made that glass, are now made that disposable plastics and used through labs roughly the world for various studies in varied fields. However, the Petri food we recognize today did not begin out this way. Enter Richard Julius Petri, a German microbiologist, who in the late 19th century operated as one assistant come the celebrated German physician and also pioneering microbiologist, Robert Koch (1843-1910). At that time Koch, was thought about to be, along with Pasteur and Lister, one of the so late nineteenth century’s “fathers of microbiology” 5.

Richard Julius Petri

Richard Julius Petri to be born in the German city the Barmen close to Wuppertal in 1852. He come from a identified family the scholars and also he to be the eldest boy of Philipp Ulrich martin Petri (1817- 1864) a professor in Berlin and also Louise Petri (his father’s cousin). His paternal grandfather was Viktor Friedrich Leberecht Petri (1782-1857), that was the professor of timeless literature and also Oriental languages and Director of the Collegium Carolinum in Braunschweig.

Richard Petri enrolled at the Kaiser Wilhelm-Akademie for military physicians native 1871 to 1875. That then carried out doctoral training as a subordinate doctor at the Berlin Charité and also received his doctorate in medicine in 1876 because that his thesis “Versuche zur Chemie des Eiweissharns” (The Chemistry of Protein urine Tests).

From 1876 until 1882 Petri practised together a military physician, serving as a volunteer through the second Foot guard Regiment. When serving together a military physician, he was assigned come a research study facility in Berlin, the Imperial health Office, working with Robert Koch. No surprisingly, the was throughout his tenure below that Petri acquired his attention in bacteriology. It is likewise where pioneering work on agar was undertaken (see box).

When Petri arrived at the lab, Koch’s aides were currently growing bacteria in fluid broth, yet Koch had realised the benefits of developing a solid culture media. He started by observing fungal “colonies” farming on slices of potato. Each nest was “pure”, containing similar organisms. However this had limitations. By put liquid societies in beef broth solidified with gelatin and also then cooling the solution, he was able to create a clear, smooth, homogeneous society medium. In it, the bacteria would multiply to kind visible colonies. The lab assistants would to water the bacteria blended with the gelatin cultivation medium on optimal of a glass slide extended with a big glass bell jar, and then incubate the totality thing. Although bacteria grew well in this medium, it had a tendency to rotate cloudy and many bacteria made enzyme that damaged down the gelatin and also turned it ago into liquid together they grew. Even when this wasn’t the case, the gelatin regularly liquefied if the laboratory ended up being too warm.

Agar jelly

Another of Koch’s assistants, Fanny Hesse (1850-1934), introduced the usage of agar jelly poured right into a shallow glass dish kept under a bell jar, together a medium on which to society the bacteria. This jelly-like however solid substance provided a rich substrate because that bacteria growth and also because it to be clear and the bacteria remained on the surface, counting and also identification came to be much easier. 

But to watch the dish’s contents under a microscope, the cover had actually to be removed, exposing the studied bacteria to untreated conditions and also contaminants. So, Petri came up through the idea of placing a slightly bigger glass lid on peak of the dish instead of a bell jar. The Petri dish to be born. As Petri explained, in his brief 1887 paper: “A minor modification of the plating an approach of Koch... Under these conditions, air pollution from airborne germs seldom occurs” 8. The innovation was straightforward and an ext compact than the bell jug and permitted for an ext efficient experiments. The cover of these new “Petri dishes” might stay on at all times to protect experiments from contamination. Similarly, the cover to be transparent and also as close as possible without poignant the media or the experimental bacteria, ensuring one could easily watch the dish.

The controversy

But to be it yes, really Petri’s idea? similar to all good scientific discoveries there is often controversy about who must be accredited for the invention. Petri’s document published in 1887 explained a change of the plating method of Koch. Some have suggested that credit should go to two various other scientists, Victor André Cornil (1837-1908) and Victor Babes (1854-1926), who released a bacteriology textbook in 1885 Bacteria and also their function in Pathological Anatomy and also Histology of contagious Diseases, that not only defined a comparable dish because that bacterial growth but included one illustration, miscellaneous Petri had actually not done. 

Also, the 3rd edition that the textbook Micro-Organisms and an illness written through Emanuel Klein (1844-1925) in the very same year, describes the dish, but here that is referred to as Koch’s bowl method. The English researcher, Percy Frankland (1858-1946) additionally published a record in 1886 in the proceedings that the royal society that explained a flat-lidded dish 9. The general agreement now is the that it had remained in use for part time before Petri released his article, however he standardised the idea the a double dish v a bigger lid. So efficient was his idea the it had spread rapidly throughout Europe and also once his record appeared, the scientific ar started specify name it after ~ him and the surname stuck.

Moving on 

After leaving Koch’s laboratory, Petri continued to be connected in bacteriology and from 1882 come 1885 he became the head that the Brehmerschen Göbersdorf sanatorium, administered by the royal Board the Health. He was a fairly vain disciplinarian who ran the tuberculosis sanatorium on strict terms because that staff and also patients. In 1886 he ended up being the director of the Museum of hygiene in Berlin, and also in 1889 he went back to the Kaiserliches Gesundheitsamt as a director from which he retired in 1900 through the title Geheimer Regierungsrat (Privy Councellor).

In addition to his inventions and innovations, Petri published virtually 150 documents on hygiene and also bacteriology. These consisted of “Ueber dice Methoden der modernen Bakterienforschung” (On the techniques of contemporary bacterial research) in 1887, “Das Mikroskop von seinen Anfängen bis zur jetzigen Vervollkommnung für alle Freunde dieses Instruments” (The microscopic lense from its starts up come the existing perfection for all lover of this instrument) in 1896, and also “Aetiologie und Therapie der chronischen Lungenschwindsucht” (Etiology and also therapy that chronic pulmonary tuberculosis) in 1902 as co-author v Hermann Brehmar (1826-1889).

Petri was also a freemason and a lodge member the the “to death’s head and also Phoenix lodge” in Königsberg v Ernst von Leyden (1832-1910) of Charcot-Leyden crystals and also Leyden-Möbius syndrome fame. Petri was married twice, his an initial wife, Anna Riesch died during childbirth in 1894 and also he remarried in 1897 come Elizabeth Turk, a marital relationship that remained childless. Petri passed away in the German city that Zeitz in 1921 in ~ the age of 69.

Routine use

The routine cultivation of bacteria and also fungi has hardly adjusted in centuries, with societies in Petri dishes and also methods used that would still it is in recognised by Robert Koch. The Petri food remained practically unmodified, except the use of plastic, and also became the most commonly used item of microbiological equipment. Recent microbial cultivation technologies, yet are beginning to encompass highly subdivided multi-well plates and capillaries, and also methods of sorting and counting encapsulated micro-colonies 10-11. By combine a printed, disposable colorimetric sensor selection into the Petri food headspace, which is responsive come the volatile building materials emitted by microorganisms during growth, that is feasible to finding the visibility of bacteria farming in the plate prior to colonies are visible 12. 

Studies have also shown the nanospray desorption electrospray ionization imaging massive spectrometry have the right to be offered for in vivo metabolic profiling of life bacterial swarms directly from the Petri food 13. Both of this can carry out a fast technique for detection and identification to enhance existing bacterial swarm counting algorithms. And now groups of researchers space making replacement organs in Petri bowl 14-15. But, too regularly these systems call for expensive, sophisticated hardware that are regularly specialised in application and it is the basic Petri dish containing a heavy jelly bowl (and the ability of the scientist, of course) that proceeds to be used in regimen microbiology laboratories.

Stephen Mortlock is Pathology Manager in ~ Nuffield Health, Guildford Hospital. 

He would favor to thank: Dr Aleksandra Pawliczek, Head Archivist at the Humboldt-Universität in Berlin; Udo Garweg, Librarian at the Von der Heydt-Museum in Wuppertal; Sabine Tolksdorf, at the Staatsbibliothek in Berlin; all the pathology staff at Guildford Hospital, Nuffield Health.

An idea, A design and a metaphor

Andrea Sella, one award-winning chemist, broadcaster and classic scientific research kit and equipment enthusiast, says: “The Petri dish has actually pretty much always stayed the very same – over there aren’t a lot of of differences that you have the right to make. 

I think the only real thing that has changed over the year is standardisation. This days Petri dishes are an extremely integrated pieces of equipment, v their traditional sizes and also their sterilised packs. 

“This advancement – the idea that the one-time, one-use, throw away – is the only real readjust to what is basically a 2D surface ar on which to prosper a culture.

It is a architecture classic – there is one elegant simplicity to the Petri dish and also I nothing think it have the right to be enhanced upon. 

“But the Petri dish exists in much more than one way: there is the article of equipment and also then over there is the meaning; the idea that a Petri dish – that communicates the notion of life scientific researches in the same means that a bubbling test tube communicates chemistry. 

“In the literal meaning sense, it will remain, together we are always thinking around the next microorganism and you’ve gained to thrive that virus somewhere. But I additionally think the the Petri dish has actually longevity in the metaphoric sense. 

“It way ‘living laboratory’ and also is offered to signify any interesting experiments that space taking place. I don’t think there’s an equivalent. 

The Petri dish, together both equipment and also idea, will be roughly for a long time.”

Jams and also jellies

While functioning at Koch’s laboratory, Walther and Fanny Hesse (nee Eilshemius) made their most renowned contribution to microbiology – one the owed as much to Fanny’s ability with jams and jellies together Walther’s specialization with bacteria. Walther Hesse (1846-1911) had actually trouble getting pure cultures, therefore he confided his disappointed to his mam Fanny and also she devised a solution. She recalled that as soon as she was growing up in brand-new York, they had a neighbour who had lived for a time in Java. The neighbour taught her family about agar-agar, a seaweed extract provided in Asia come solidify jellies and thicken soups. Fanny had actually been utilizing agar-agar in her jams for years. 

Walther found that agar-agar was perfect to solidify the beef broth. In ~ 100°C, it can be melted, combined with the liquid broth and poured into dishes. The new medium was solid at room temperature and above. Bacteria prospered well ~ above it but they could not rest it down. Agar-agar was also translucent, which make identifying bacter colonies and also their qualities much easier. Though it’s simply referred to as agar now, the substance used in microbiology labs is the exact same one the originated in Fanny Hesse’s kitchen.

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