AAT Bioquest

How do I obtain a pure culture?

Posted November 6, 2023


A pure culture is obtained by transferring a small sample onto a sterile growth medium so that a single cell takes up an isolated area on the agar surface. This is done through the scattering of cells across the agar surface, which has 3 methods. One method is the spread plate technique, in which the original culture is diluted and a small volume of the resulting dilution is spread on the agar surface. Another method is the streak plate technique, in which the original culture is directly applied across the agar surface using an inoculating loop. A third method is the pour plate technique, in which culture is diluted and a small amount of the resulting solution is added to molten agar. This is then poured over the plate and hardens overtime to allow for colonies to produce. All 3 of these methods thin out and isolate the individual cells so that when they grow, they will form a separate colony with only one type of organism. The colony can be used to inoculate more mediums. The isolation of a pure culture may be improved by using a mixed inoculum with a medium which supports the development of one organism and excludes others.

Additional resources

Obtaining Pure Culture From a Mixed Population

Cell Proliferation Assays

Screen Quest™ CHO-Gqs Chimera Cell line