Julius Richard Petri
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Julius Richard Petri (; 31 May 185220 December 1921) was a German
microbiologist A microbiologist (from Greek ) is a scientist who studies microscopic life forms and processes. This includes study of the growth, interactions and characteristics of microscopic organisms such as bacteria, algae, fungi, and some types of par ...
who is generally credited with inventing the device known as the
Petri dish A Petri dish (alternatively known as a Petri plate or cell-culture dish) is a shallow transparent lidded dish that biologists use to hold growth medium in which cells can be cultured,R. C. Dubey (2014): ''A Textbook Of Biotechnology For Class- ...
, which is named after him, while working as assistant to
bacteriologist A bacteriologist is a microbiologist, or similarly trained professional, in bacteriology— a subdivision of microbiology that studies bacteria, typically Pathogenic bacteria, pathogenic ones. Bacteriologists are interested in studying and learnin ...
Robert Koch Heinrich Hermann Robert Koch ( ; ; 11 December 1843 – 27 May 1910) was a German physician and microbiologist. As the discoverer of the specific causative agents of deadly infectious diseases including tuberculosis, cholera and anthrax, he i ...
.


Life and career

Petri was born in the town of
Barmen Barmen is a former industrial metropolis of the region of Bergisches Land, Germany, which merged with four other towns in 1929 to form the city of Wuppertal. Barmen, together with the neighbouring town of Elberfeld founded the first electric ...
(now a district of the city of
Wuppertal Wuppertal (; ) is a city in North Rhine-Westphalia, in western Germany, with a population of 355,000. Wuppertal is the seventh-largest city in North Rhine-Westphalia and List of cities in Germany by population, 17th-largest in Germany. It ...
), Germany, on 31 May 1852. He came from a distinguished family of scholars, and was the eldest son of Philipp Ulrich Martin Petri (18171864), a professor in Berlin, and Louise Petri. Petri's grandfather, Viktor Friedrich Leberecht Petri (1782–1857), was also a scholar, being both a director and professor at the Collegium Carolinum in Brunswick (Braunschweig), Germany. Petri initially studied medicine at the Kaiser Wilhelm Academy for Military Physicians (18711875) and received his medical degree in 1876. He continued his studies at the
Charité The Charité – Universitätsmedizin Berlin (Charité – Berlin University of Medicine; ) is Europe's List of hospitals by capacity, largest university hospital, affiliated with Humboldt University of Berlin, Humboldt University and the Free ...
Hospital in
Berlin Berlin ( ; ) is the Capital of Germany, capital and largest city of Germany, by both area and List of cities in Germany by population, population. With 3.7 million inhabitants, it has the List of cities in the European Union by population withi ...
where his thesis on the chemistry of protein urine tests earned him his doctorate. He was on active duty as a military physician until 1882, continuing then as a reservist. In 1886 he was a curator at the
German Hygiene Museum The German Hygiene Museum () is a medical museum in Dresden, Germany. It conceives itself today as a "forum for science, culture and society". It is a popular venue for events and exhibitions, and is among the most visited museums in Dresden, wit ...
where he subsequently worked under Robert Koch. In 1900 he retired, while still remaining a secret government advisor, until his demise. From 1877 to 1879 he was assigned to the Imperial Health Office () in
Berlin Berlin ( ; ) is the Capital of Germany, capital and largest city of Germany, by both area and List of cities in Germany by population, population. With 3.7 million inhabitants, it has the List of cities in the European Union by population withi ...
, where he became an assistant to Robert Koch. On the suggestion of Angelina Hesse, the
New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...
-born wife of another assistant, Walther Hesse, the Koch laboratory began to culture bacteria on
agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from " ogonori" and " tengusa". As found in nature, agar is a mixture of two components, t ...
plates. Petri then invented the standard culture dish, or Petri plate, and further developed the technique of agar culture to purify or clone
bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
l
colonies A colony is a territory subject to a form of foreign rule, which rules the territory and its indigenous peoples separated from the foreign rulers, the colonizer, and their '' metropole'' (or "mother country"). This separated rule was often or ...
derived from single cells. This advance made it possible to rigorously identify the bacteria responsible for diseases. Petri's first wife, Anna Riesch, died in 1894 during childbirth. In 1897, he married Elizabeth Turk.


Importance of the Petri dish and his discoveries

Petri dishes are used as research plates for
microbiology Microbiology () is the branches of science, scientific study of microorganisms, those being of unicellular organism, unicellular (single-celled), multicellular organism, multicellular (consisting of complex cells), or non-cellular life, acellula ...
studies. The dish is partially filled with warm liquid containing
agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from " ogonori" and " tengusa". As found in nature, agar is a mixture of two components, t ...
, and a mixture of specific ingredients that may include nutrients, blood, salts,
carbohydrates A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ma ...
, dyes, indicators,
amino acids Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the Proteinogenic amino acid, 22 α-amino acids incorporated into p ...
and
antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...
. After the agar cools and solidifies, the dish is ready to receive a microbe-laden sample in a process known as "inoculation" or "plating". For virus or
phage A bacteriophage (), also known informally as a phage (), is a virus that infects and replicates within bacteria. The term is derived . Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome, and may have structures tha ...
cultures, a two-step inoculation is needed: bacteria that is grown acts like a host for the viral inoculum. The bacterial sample is diluted on the plate in a process called "
streaking Streaking is the act of running naked through a public area for publicity, for fun, as a prank, a dare, a form of protest, or to participate in a fad. Streaking is often associated with sporting events, but can occur in more secluded areas. Str ...
": a sterile plastic stick, or a wire loop which is sterilized by heating; the loop is used to collect the first sample, and then to make a streak on the dish with the agar. Then, using a fresh stick and sterilized loop, the new loop is passed through that initial streak, spreading the plated bacteria onto the dish. This process is repeated a third time, and if necessary a fourth, resulting in individual bacterial cells that are isolated on the plate, which then are capable to divide and grow into single "clonal" bacterial colonies. Petri plates can be incubated upside down (agar on top), which can help lessen the risk of contamination from airborne particles containing microbes settling and to decrease and prevent the chance of condensation from water accumulating and disturbing the microbes being cultured. Scientists had long been growing cells in natural and synthetic matrix environments to elicit
phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological propert ...
s that are not expressed on conventionally rigid substrates. Unfortunately, growing cells either on or within soft matrices can be an expensive, labor-intensive, and impractical undertaking. The basic design of the Petri dish has not changed since being created by Petri in 1887. It was a challenge to keep dishes free of dust and extra bacteria that could collect and alter samples; heavy bell jars used for this purpose having proved ineffective, six years later Petri created a transparent plate slightly larger than the dish, which served as a transparent lid. After his invention of the Petri dish, Petri left Koch's laboratory and ran the Göbersdorf sanatorium for Tuberculosis patients from 1882 to 1885. After running the Göbersdorf sanatorium, he became the director of the Museum of Hygiene in Berlin in the year 1886. Not only was Petri responsible for many innovations and inventions, he also published a variety of papers including 150 on the topic of bacteriology and hygiene, which contributed significantly to information and concepts related to them. Petri's papers detailed a number of steps in understanding microbiology, not limited to the study of microorganisms but also including biological pathways and mechanisms. In his paper of 1876 he considered questions regarding
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
s found within urine seeking ways that they could be used to identify conditions or functions.


Works

*''Attempts at the chemistry of proteins.'' 1876. *''Methods of modern bacteria research (in: Collection Exoteric Scientific Lectures).'' 1887. *''The danger of carbon soda furnaces.'' 1889. *''Industrial hygiene.'' 1890. *''Experiments on the spread of contagious diseases, especially tuberculosis, by the railway and on measures to be taken.'' 1893. *''The microscope. From its beginnings to the present perfection.'' 1896. *''A judgment of highpressure Pasteurising apparatus'' 1897. *''Towards quality testing in butter and milk.'' 1897. *''Apparatus for determination of water content in milk by distillation in a vacuum.''


References


Sources

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External links


Whonamedit

Petri dish


{{DEFAULTSORT:Petri, Julius Richard 1852 births 1921 deaths 19th-century German biologists German microbiologists German bacteriologists Scientists from Wuppertal 20th-century German biologists