A Petri dish (Petri plate) is a shallow cylindrical glass lidded dish that is typically used to culture microorganisms (agar plates). There are glass and plastic Petri dishes, and both can be sterilized (using an autoclave) and re-used. Before being used for culture purposes, it is important to ensure that the Petri dish is not only clean, but also sterile. This helps prevent the contamination of the new culture.
Agar is a polymer made up of various sub-units of galactose and various species of red algae. Although it has other uses including culinary and dentistry, agar plays an important role in microbiology as culture media for a variety of microorganisms.
As compared to some of the other alternatives like gelatin, agar has a number of advantages which include:
Cannot be easily degraded by microorganisms
Stronger
Firmer than gelatin
Depending on the type or strain of bacteria being grown, there are different types of agar that may be recommended. Although great care has to be taken when handling any culture, plain nutrient agar, rather than an agar formulation that supports pathogenic bacteria is recommended for younger students or in the case of home experiments.
Post time: May-17-2021