Microbiological culture

Microbiological culture

Overview

A microbiological culture, or microbial culture, is a method of multiplying microbial organisms
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

 by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested, or both. It is one of the primary diagnostic
Medical diagnosis
Medical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...

 methods of microbiology
Microbiology
Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...

 and used as a tool to determine the cause of infectious disease
Infectious disease
Infectious diseases, also known as communicable diseases, contagious diseases or transmissible diseases comprise clinically evident illness resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism...

 by letting the agent multiply in a predetermined medium.
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Encyclopedia

A microbiological culture, or microbial culture, is a method of multiplying microbial organisms
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

 by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested, or both. It is one of the primary diagnostic
Medical diagnosis
Medical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...

 methods of microbiology
Microbiology
Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...

 and used as a tool to determine the cause of infectious disease
Infectious disease
Infectious diseases, also known as communicable diseases, contagious diseases or transmissible diseases comprise clinically evident illness resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism...

 by letting the agent multiply in a predetermined medium. For example, a throat culture is taken by scraping the lining of tissue in the back of the throat and blotting the sample into a medium to be able to screen for harmful microorganisms, such as Streptococcus pyogenes
Streptococcus pyogenes
Streptococcus pyogenes is a spherical, Gram-positive bacterium that is the cause of group A streptococcal infections. S. pyogenes displays streptococcal group A antigen on its cell wall. S...

, the causative agent of strep throat. Furthermore, the term culture is more generally used informally to refer to "selectively growing" a specific kind of microorganism in the lab.

Microbial cultures are foundational and basic diagnostic methods used extensively as a research tool in molecular biology
Molecular biology
Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...

. It is often essential to isolate a pure culture of microorganisms. A pure (or axenic) culture is a population of cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

s or multicellular organisms growing in the absence of other species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 or types. A pure culture may originate from a single cell or single organism, in which case the cells are genetic clones
Clones
Clones is a small town in western County Monaghan, in the 'border area' of the Republic of Ireland. The area is part of the Border Region, earmarked for economic development by the Irish Government due to its currently below-average economic situation...

 of one another.

For the purpose of gelling the microbial culture, the medium of agarose gel (agar) is used. Agar is a gelatinous substance derived from seaweed. A cheap substitute for agar is guar gum, which can be used for the isolation and maintenance of thermophiles.

Bacterial culture


Microbiological cultures can be grown in petri dish
Petri dish
A Petri dish is a shallow glass or plastic cylindrical lidded dish that biologists use to culture cells or small moss plants. It was named after German bacteriologist Julius Richard Petri, who invented it when working as an assistant to Robert Koch...

es of differing sizes that have a thin layer of agar-based growth medium. Once the growth medium in the petri dish is inoculated with the desired bacteria, the plates are incubated at the best temperature for the growing of the selected bacteria (for example usually at 37 degrees Celsius for cultures from humans or animals, or lower for environmental cultures).

Another method of bacterial culture is liquid culture, in which the desired bacteria are suspended in liquid broth, a nutrient medium. These are ideal for preparation of an antimicrobial assay. The experimenter would inoculate liquid broth with bacteria and let it grow overnight (they may use a shaker for uniform growth). Then they would take aliquots of the sample to test for the antimicrobial activity of a specific drug or protein (antimicrobial peptides
Antimicrobial peptides
Antimicrobial peptides are an evolutionarily conserved component of the innate immune response and are found among all classes of life. Fundamental differences exist between prokaryotic and eukaryotic cells that may represent targets for antimicrobial peptides...

).

Alternatively, the microbiologist may decide to use static liquid cultures. These cultures are not shaken and they provide the microbes with an oxygen gradient.

The main ones being:
Collection Acronym Name Location
ATCC American Type Culture Collection
American Type Culture Collection
The American Type Culture Collection is a private, not-for-profit biological resource center whose mission focuses on the acquisition, authentication, production, preservation, development and distribution of standard reference microorganisms, cell lines and other materials for research in the...

Manassas, Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

NCTC National Collection of Type Cultures
National Collection of Type Cultures
National Collection of Type Cultures is one of the four organizations that constitutes the HPA Culture Collections. It is a non-profit culture collection repository located in UK. NCTC maintains over 5000 bacterial cultures, over 100 mycoplasmas and more than 500 plasmids, host strains,...

Health Protection Agency
Health Protection Agency
The Health Protection Agency, or, in Welsh, Yr Asiantaeth Diogelu Iechyd is a statutory corporation. It is an independent UK organisation that was set up by the government in 2003 to protect the public from threats to their health from infectious diseases and environmental hazards...

, United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

BCCM Belgium Coordinated Collection of Microorganism
Belgian Co-ordinated Collections of Micro-organisms
The Belgian Co-ordinated Collections of Micro-organisms is a Belgian government funded consortium of four scientific institutions, who manage and exploit a collection of fungi, bacteria and plasmids...

Ghent
Ghent
Ghent is a city and a municipality located in the Flemish region of Belgium. It is the capital and biggest city of the East Flanders province. The city started as a settlement at the confluence of the Rivers Scheldt and Lys and in the Middle Ages became one of the largest and richest cities of...

, Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

CIP Collection d'Institut Pasteur Paris
Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

DSMZ Deutsche Sammlung von Mikroorganismen und Zellkulturen
Deutsche Sammlung von Mikroorganismen und Zellkulturen
The Deutsche Sammlung von Mikroorganismen und Zellkulturen - DSMZ - GmbH was founded 1969 as the national culture collection in Germany...

Braunschweig
Braunschweig
Braunschweig , is a city of 247,400 people, located in the federal-state of Lower Saxony, Germany. It is located north of the Harz mountains at the farthest navigable point of the Oker river, which connects to the North Sea via the rivers Aller and Weser....

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

JCM Japan Collection of Microorganisms
Japan Collection of Microorganisms
Japan Collection of Microorganisms is a culture collection of microorganisms in Japan. It is a semi-governmental collection maintained by RIKEN BioResource Center and it is located in Saitama Prefecture. JCM was initiated in 1980 with the purpose of serving as a repository of microorganisms...

Saitama
Saitama, Saitama
' is the capital and the most populous city of Saitama Prefecture in Japan, situated in the south-east of the prefecture. Its area incorporates the former cities of Urawa, Ōmiya, Yono and Iwatsuki. It is a city designated by government ordinance...

, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

NCCB Netherlands Culture Collection of Bacteria Utrecht
Utrecht
Utrecht is a city in the Netherlands.The name may also refer to:* Utrecht , of which Utrecht is the capital* Utrecht , including the city of Utrecht* Bishopric of Utrecht* Roman Catholic Archdiocese of Utrecht...

, Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

NCIMB National Collection of industrial, Marine and food bacteria Aberdeen
Aberdeen
Aberdeen is Scotland's third most populous city, one of Scotland's 32 local government council areas and the United Kingdom's 25th most populous city, with an official population estimate of ....

, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...


Virus and phage culture


Virus or phage cultures require host cells in which the virus or phage multiply. For bacteriophage
Bacteriophage
A bacteriophage is any one of a number of viruses that infect bacteria. They do this by injecting genetic material, which they carry enclosed in an outer protein capsid...

s, cultures are grown by infecting bacterial cells. The phage can then be isolated from the resulting plaques in a lawn of bacteria on a plate. Virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

 cultures are obtained from their appropriate eukaryotic host cells.

Isolation of pure cultures



For single-celled eukaryotes, such as yeast, the isolation of pure cultures uses the same techniques as for bacterial cultures. Pure cultures of multicellular organisms are often more easily isolated by simply picking out a single individual to initiate a culture. This is a useful technique for pure culture of fungi, multicellular algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

, and small metazoa, for example.
m/M;

Developing pure culture techniques is crucial to the observation of the specimen in question. The most common method to isolate individual cells and produce a pure culture is to prepare a streak plate. The streak plate method is a way to physically separate the microbial population, and is done by spreading the inoculate back and forth with an inoculating loop over the solid agar plate. Upon incubation, colonies will arise and, hopefully, single cells will have been isolated from the biomass.

External links

  • http://www.effca.org, www.effca.org - European Food and Feed Cultutes Association - EFFCA. Information about production and uses of microbial cultures as well as legislative aspects.

See also

  • Blood culture
    Blood culture
    Blood culture is a microbiological culture of blood. It is employed to detect infections that are spreading through the bloodstream...

  • Sputum culture
    Sputum culture
    A sputum culture is a test to detect and identify bacteria or fungi that infect the lungs or breathing passages. Sputum is a thick fluid produced in the lungs and in the adjacent airways. A sample of sputum is placed in a sterile container and sent to the laboratory for testing...

  • Screening cultures
    Screening cultures
    Screening culture is a type a medical test that is done to find an infection. Screening cultures are often performed to find infections that do not have signs and symptoms.-Types of screening cultures:...

  • Synchronous culture
    Synchronous culture
    A synchronous or synchronized culture is a microbiological culture or a cell culture that contains cells that are all in the same growth stage....

  • NCPPB
  • ICMP
  • DSMZ
    Deutsche Sammlung von Mikroorganismen und Zellkulturen
    The Deutsche Sammlung von Mikroorganismen und Zellkulturen - DSMZ - GmbH was founded 1969 as the national culture collection in Germany...