Serial dilution technique-

Listar and his coworkers employed this technique to separate a single species from a mixture in which it was a predominating type. A small amount of the material, which contains mixture of bacteria is added to a test tube containing sterile medium of known volume. A stage will be reached when higher dilutions will contain no organisms and will show no growth upon incubation. Some of the tubes of higher dilution showing will be found to contain only one colony of a species, which can be ascertained by microscopic examination.





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Streak plate technique-

The inoculum is streaked or spread over the surface of a solid medium. The streaking process accomplishes a thinking out of the population. There is no uniform distribution of the organism. Where they are thickly populated, they will grow in mass, but where only few are present, they develop distinct colonies. These isoalated colonies are the progenies of single cells and whether they are so may be verified from microscopic examination. Pure culture may be recurred by the transfer of a part of such colonies to a container with suitable culture medium.

Single-cell isolation technique-

The best way to secure a pure culture from a mixed one would like to pick out a single cell of the desired type. This can be done by the use of micromanipulator in contamination with a microscope. Micromanipulator has a micropipette with a very fine capillary point. The micropipette can be moved as desire. A single cell can be picked using micropipette and transferred to a suitable nutrient medium.

Disadvantages-
This technique requires a skilled operator, is cumbersome to operate and involves greater chances of contamination during operation.