In the late 19th century, the pre-assembly of finished products was promoted
Finished pre-loaded culture medium plate, also known asready-to-use medium, which has been sterilized and packaged, and there is no need to weigh the sterilized and packaged medium that can be used directly.
In the late 19th century, the famous German bacteriologist Robert Koch (1843-1910) successfully prepared solid culture media and invented glass plates, which revolutionized bacteriology and greatly promoted the isolation, culture and identification of bacteria. At the same time, it also promoted the development of finished pre-packaged culture media plates to meet the needs of microbial detection.
In order to directly observe the shape and growth of microorganisms, scientists hope to cultivate microorganisms on solid surfaces, just as microorganisms grow on orange peels or potatoes. Robert Koch used boiled and sterilized potatoes to grow bacteria. Since then, he has tried to use gelatin as a coagulant for the medium. He added gelatin to the liquid medium to melt, and then slowly poured the mixed liquid on the surface of a glass plate. When the gelatin cools and solidifies, a solid medium forms on the surface of the glass plate. To prevent the contamination of bacteria in the air, Koch also used a glass cover to isolate the glass plate from the surrounding environment.
However, it was soon discovered that the solidification force of gelatin is very weak. The gelling temperature varies with the concentration and the type of coexisting salts, concentration, pH of the solution, etc. The difference between the dissolution temperature and the solidification temperature is very small. Gelatin becomes soft above 20 ° C, and the scribing operation to separate microorganisms is very difficult. At temperatures above 25 ° C, gelatin liquefies, and most bacteria are cultured at temperatures above 25 ° C.
Robert Koch's colleague Walter Hesse was also troubled by the same problem. Once, Walter Hesse's wife Fannie suggested that he try agar as a coagulant, because Fannie did a good job of using agar as a jelly. Walter Hesse took his wife's advice and found that agar was a better coagulant for media than gelatin, which led to a major improvement in the technology of solid media.
In 1887, Richard Petri made a further improvement on the Koch plate technology. Petri designed a round, rimmed double plate, with the large plate serving as the lid and the small plate serving as the bottom. To prepare solid medium, melt the medium into the small plate, and then use the large plate to cover the small plate. This is the Petri plate we use today.
Since then, there have been world-famous companies specializing in the production of media such as Difco in the United States and Oxoid in the United Kingdom. Among them, Difco in the United States has a history of more than 100 years. It began to produce dehydrated and dried media in 1917; it began to commercialize finished pre-packaged media flat dishes in 1979. The product entered the Chinese market in 1994.
Our country began to develop dry media in the late 1950s, and now there are more than 100 media manufacturers, and more than 300 varieties of dry powder media. In recent decades, our country's media industry has developed rapidly, and great progress has been made in the research, development and production of raw materials, which has greatly shortened the gap with developed countries.
According to some data, the earliest petri plate unit produced in China was the Kuomintang Central Epidemic Prevention Office, that is, the Kunming Institute of Biological Products established after the founding of the People's Republic of China. Its preparation process was 1:2 beef soup, plus peptone, sodium chloride, and strip agar. It was fully dissolved by heating to replenish water for bandwidth evaluation; then 20% sodium hydroxide was used to adjust the pH value to 7.6, then heated and boiled, and divided into 500ml Kirschner bottles. Each bottle was divided into 250ml. After the division was completed, it was sterilized at 121 degrees for 15 minutes at high temperature. After the sterilization was completed, it was cooled to 50 degrees. It was divided into sterilized glass plates in a clean environment and under flame protection. After being cooled and solidified, it was placed in a 37-degree incubator for 3 days. If there was no pollution, it was considered a qualified product.
With the development of market economy and the disadvantages of short valid period and high cost of hand-prepared flat dishes, small workshop-style manual production has been difficult to meet the needs of industrial large-scale production. Such an era background has created a feasible way for the commercialization of finished pre-packaged petri flat dishes. In the 1980s, domestic commercialized finished pre-packaged petri flat dishes appeared in the Chinese market, and are currently being used more and more widely. However, there are no market management measures and unified Quality Standards and control methods, resulting in the lack of stability and standardization of the quality of commercialized petri flat dishes, which directly affects the accuracy and reliability of microbial detection results in clean areas.
With the continuous improvement and optimization of the "Good Manufacturing Practice for Drugs" and the "Chinese Pharmacopoeia", the detection and operation methods of microorganisms in clean areas are also standardized. In short, in order to meet the expected quality requirements of drugs, it is necessary to ensure the authenticity of the level of microbial contamination in clean areas during the production of drugs, so it is necessary to choose a culture medium plate that meets the quality requirements to manage and control the environment of clean areas throughout the process.
