Importance of serial dilution in microbiology

24 hours old nutrient broth culture of two different organisms.The pure colonies which are of varying size, shape and colour may be isolated/transported into test tube culture media to prepare pure cultures.

In this Method, serial dilutions of the inoculum (serially diluting the primary specimen) are added within sterile Petri plates to which is poured melted and cooled (42-45Р В Р вЂ Р вЂ™Р’ВР В Р вЂ°) agar medium and completely mixed by revolving the plates which are then left to solidify.Р В РІР‚СњР В РІР‚С›fter incubation, the plates are observed for the appearance of individual colonies growing everywhere in the medium. The main purpose of the pour plate method is to isolate the pure culture from a mixture of different populations and demonstrate the cultural characteristics of the bacteria such as color, texture, size, elevation etc. This method also used to count the number of viable organisms in a liquid such as water, milk, urine or broth culture as well as to determine the hemolytic activity of deep colonies of some bacteria, such as the streptococci, by using an agar medium containing blood. In normally microbial population exists as a mixture of many other cell types, this laboratory technique is used to produce pure culture from these population.

The forerunner of the present pour-plate method was developed in the laboratory of the famous bacteriologist, Robert Koch.

Importance of serial dilution in microbiology