The Petri Dish!

Google is commemorating today the achievements of the scientist Julius Richard Petri with a Google Doodle that shows his invention - the Petri dish - in action.

Today would have been the German bacteriologist's 160th birthday. In the animation on the Google homepage, the word "Google" is replaced with a series of the dishes in the Google colours. A hand appears, swabbing each of them, then you can watch as the bacteria grow.

 

Julius Richard Petri (May 31, 1852 – December 20, 1921) was a German microbiologist who is generally credited with inventing the Petri dish while working as assistant to pioneering bacteriologist Robert Koch.

 

Petri dishes are often used to make plates that are used for microbiology studies. The dish is partially filled with warm liquid containing agar, and a mixture of specific ingredients that may include nutrients, blood, salts, carbohydrates, dyes, indicators, amino acids and antibiotics. 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 cultures, a two-step inoculation is needed: bacteria are grown first to provide hosts for the viral inoculum.

Often, the bacterial sample is diluted on the plate by a process called "streaking": a sterile plastic stick, or a wire loop which has been sterilized by heating is used to take the first sample, and make a streak on the agar dish. Then a fresh stick, or a newly-sterilized loop, passes through that initial streak, and spreads the plated bacteria onto the dish. This is repeated a third, and sometimes a fourth time, resulting in individual bacterial cells that are isolated on the plate, which then divide and grow into single "clonal" bacterial colonies.
Petri plates are sometimes incubated upside down (agar on top) to lessen the risk of contamination from settling airborne particles and to prevent water condensation from accumulating and disturbing the cultured microbes.

P&R Labpak supply a wide range of petri dishes - glass and disposable plastic in various diameters.  If you need any, why not contact us?

We also supply various agars and media from all leading brands.

 

For more information visit:-

http://en.wikipedia.org/wiki/Julius_Richard_Petri

http://www.independent.co.uk/life-style/gadgets-and-tech/news/google-doodle-celebrates-work-of-julius-richard-petri--the-scientist-widely-credited-with-inventing-the-petri-dish-8638084.html

What is Culture Media?

Because microorganisms are so small, sometimes very large colonies of them are necessary for any kind of experimentation or to determine treatment for disease. To get populations big enough to be studied, scientist have to be able to grow them efficiently, and to do that they use culture media. While the culture media used are in liquid or gelatinous form, often culture media are sold and shipped as dehydrated powders so that they can be mixed up as necessary. It is also important for researchers to know what nutrients suspected pathogens need in order to grow them.

When researchers know how to successfully grow pathogens in a growth medium, they can gain insight into how these substances are harmful. As an example, pseudomonas aeruginosa, a pathogen found in cystic fibrosis patients and burn patients express their genes for virulence in conditions of medium or low iron. Therefore, when a culture is done from one of these patients in a low iron culture, growth of the organisms signal that they are present inside a host and can influence the types of treatment a patient receives.

To determine what goes into a dehydrated culture medium, it is necessary to know the nutritional requirements of the cells that are to be cultured. Once these structures are broken down, they are found to be made up of lipids, amino acids, nucleic acids, sugars, and other compounds. Knowing the chemical formulations of these compounds allows scientists to make an accurate estimate of the cell’s nutritional requirements.

Over time, a body of knowledge is created about strains of bacteria or other microorganisms and their nutritional needs. Culture media are fine-tuned for specific applications. Dehydrated culture media are manufactured for convenience of researchers. With dehydrated media, researchers can mix up custom quantities that are tailored to their unique research needs.

P&R Labpak supply a range of media to suit all applications.